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• javascript ajax save opened pdf

  - by Jovo Krneta

  I was wondering if I could open a pdf in new browser window ,sign it with a smart card ,save it (without file download) and send it back (upload from new browser window ) by using javascript,ajax and php.I can also use javascript inside pdf(call javascript inside pdf). I was thinking something like getElementsByTagName('body')[0].innerHTML of a pdf document, then pass this to php using ajax and saving to server.Can I do this...

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• How can I download a script using Javascript and supply a header to the GET?

  - by Alan

  I have this method for downloading a script: var script = document.createElement('script'); script.setAttribute("src", url); document.getElementsByTagName("head")[0].appendChild(script); This gives me a GET like this: GET http://127.0.0.1:17315/Scripts/abc.js HTTP/1.1 However I need to add a header: Authorization: Bearer Ipnsfm9h1MWYIM0n1ng Can anyone tell me how I can add a header when I am using Javascript to perform the GET?

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• why does twitter use the !function syntax in their embed code

  - by samccone

  I was looking at twitters embed code and saw that they are using !function ... while i know that this evaluates to false I was wondering what the point of it was. thoughts? !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs");

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• GZip/Deflate Compression in ASP.NET MVC

  - by Rick Strahl

  A long while back I wrote about GZip compression in ASP.NET. In that article I describe two generic helper methods that I've used in all sorts of ASP.NET application from WebForms apps to HttpModules and HttpHandlers that require gzip or deflate compression. The same static methods also work in ASP.NET MVC. Here are the two routines:/// <summary> /// Determines if GZip is supported /// </summary> /// <returns></returns> public static bool IsGZipSupported() { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (!string.IsNullOrEmpty(AcceptEncoding) && (AcceptEncoding.Contains("gzip") || AcceptEncoding.Contains("deflate"))) return true; return false; } /// <summary> /// Sets up the current page or handler to use GZip through a Response.Filter /// IMPORTANT: /// You have to call this method before any output is generated! /// </summary> public static void GZipEncodePage() { HttpResponse Response = HttpContext.Current.Response; if (IsGZipSupported()) { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (AcceptEncoding.Contains("gzip")) { Response.Filter = new System.IO.Compression.GZipStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.Headers.Remove("Content-Encoding"); Response.AppendHeader("Content-Encoding", "gzip"); } else { Response.Filter = new System.IO.Compression.DeflateStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.Headers.Remove("Content-Encoding"); Response.AppendHeader("Content-Encoding", "deflate"); } } // Allow proxy servers to cache encoded and unencoded versions separately Response.AppendHeader("Vary", "Content-Encoding"); } The first method checks whether the client sending the request includes the accept-encoding for either gzip or deflate, and if if it does it returns true. The second function uses IsGzipSupported() to decide whether it should encode content and uses an Response Filter to do its job. Basically response filters look at the Response output stream as it's written and convert the data flowing through it. Filters are a bit tricky to work with but the two .NET filter streams for GZip and Deflate Compression make this a snap to implement. In my old code and even now in MVC I can always do:public ActionResult List(string keyword=null, int category=0) { WebUtils.GZipEncodePage(); …} to encode my content. And that works just fine. The proper way: Create an ActionFilterAttribute However in MVC this sort of thing is typically better handled by an ActionFilter which can be applied with an attribute. So to be all prim and proper I created an CompressContentAttribute ActionFilter that incorporates those two helper methods and which looks like this:/// <summary> /// Attribute that can be added to controller methods to force content /// to be GZip encoded if the client supports it /// </summary> public class CompressContentAttribute : ActionFilterAttribute { /// <summary> /// Override to compress the content that is generated by /// an action method. /// </summary> /// <param name="filterContext"></param> public override void OnActionExecuting(ActionExecutingContext filterContext) { GZipEncodePage(); } /// <summary> /// Determines if GZip is supported /// </summary> /// <returns></returns> public static bool IsGZipSupported() { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (!string.IsNullOrEmpty(AcceptEncoding) && (AcceptEncoding.Contains("gzip") || AcceptEncoding.Contains("deflate"))) return true; return false; } /// <summary> /// Sets up the current page or handler to use GZip through a Response.Filter /// IMPORTANT: /// You have to call this method before any output is generated! /// </summary> public static void GZipEncodePage() { HttpResponse Response = HttpContext.Current.Response; if (IsGZipSupported()) { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (AcceptEncoding.Contains("gzip")) { Response.Filter = new System.IO.Compression.GZipStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.Headers.Remove("Content-Encoding"); Response.AppendHeader("Content-Encoding", "gzip"); } else { Response.Filter = new System.IO.Compression.DeflateStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.Headers.Remove("Content-Encoding"); Response.AppendHeader("Content-Encoding", "deflate"); } } // Allow proxy servers to cache encoded and unencoded versions separately Response.AppendHeader("Vary", "Content-Encoding"); } } It's basically the same code wrapped into an ActionFilter attribute, which intercepts requests MVC requests to Controller methods and lets you hook up logic before and after the methods have executed. Here I want to override OnActionExecuting() which fires before the Controller action is fired. With the CompressContentAttribute created, it can now be applied to either the controller as a whole:[CompressContent] public class ClassifiedsController : ClassifiedsBaseController { … } or to one of the Action methods:[CompressContent] public ActionResult List(string keyword=null, int category=0) { … } The former applies compression to every action method, while the latter is selective and only applies it to the individual action method. Is the attribute better than the static utility function? Not really, but it is the standard MVC way to hook up 'filter' content and that's where others are likely to expect to set options like this. In fact,  you have a bit more control with the utility function because you can conditionally apply it in code, but this is actually much less likely in MVC applications than old WebForms apps since controller methods tend to be more focused. Compression Caveats Http compression is very cool and pretty easy to implement in ASP.NET but you have to be careful with it - especially if your content might get transformed or redirected inside of ASP.NET. A good example, is if an error occurs and a compression filter is applied. ASP.NET errors don't clear the filter, but clear the Response headers which results in some nasty garbage because the compressed content now no longer matches the headers. Another issue is Caching, which has to account for all possible ways of compression and non-compression that the content is served. Basically compressed content and caching don't mix well. I wrote about several of these issues in an old blog post and I recommend you take a quick peek before diving into making every bit of output Gzip encoded. None of these are show stoppers, but you have to be aware of the issues. Related Posts GZip Compression with ASP.NET Content ASP.NET GZip Encoding Caveats© Rick Strahl, West Wind Technologies, 2005-2012Posted in ASP.NET  MVC   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• DropDownList and SelectListItem Array Item Updates in MVC

  - by Rick Strahl

  So I ran into an interesting behavior today as I deployed my first MVC 4 app tonight. I have a list form that has a filter drop down that allows selection of categories. This list is static and rarely changes so rather than loading these items from the database each time I load the items once and then cache the actual SelectListItem[] array in a static property. However, when we put the site online tonight we immediately noticed that the drop down list was coming up with pre-set values that randomly changed. Didn't take me long to trace this back to the cached list of SelectListItem[]. Clearly the list was getting updated - apparently through the model binding process in the selection postback. To clarify the scenario here's the drop down list definition in the Razor View:@Html.DropDownListFor(mod => mod.QueryParameters.Category, Model.CategoryList, "All Categories") where Model.CategoryList gets set with:[HttpPost] [CompressContent] public ActionResult List(MessageListViewModel model) { InitializeViewModel(model); busEntry entryBus = new busEntry(); var entries = entryBus.GetEntryList(model.QueryParameters); model.Entries = entries; model.DisplayMode = ApplicationDisplayModes.Standard; model.CategoryList = AppUtils.GetCachedCategoryList(); return View(model); } The AppUtils.GetCachedCategoryList() method gets the cached list or loads the list on the first access. The code to load up the list is housed in a Web utility class. The method looks like this:/// <summary> /// Returns a static category list that is cached /// </summary> /// <returns></returns> public static SelectListItem[] GetCachedCategoryList() { if (_CategoryList != null) return _CategoryList; lock (_SyncLock) { if (_CategoryList != null) return _CategoryList; var catBus = new busCategory(); var categories = catBus.GetCategories().ToList(); // Turn list into a SelectItem list var catList= categories .Select(cat => new SelectListItem() { Text = cat.Name, Value = cat.Id.ToString() }) .ToList(); catList.Insert(0, new SelectListItem() { Value = ((int)SpecialCategories.AllCategoriesButRealEstate).ToString(), Text = "All Categories except Real Estate" }); catList.Insert(1, new SelectListItem() { Value = "-1", Text = "--------------------------------" }); _CategoryList = catList.ToArray(); } return _CategoryList; } private static SelectListItem[] _CategoryList ; This seemed normal enough to me - I've been doing stuff like this forever caching smallish lists in memory to avoid an extra trip to the database. This list is used in various places throughout the application - for the list display and also when adding new items and setting up for notifications etc.. Watch that ModelBinder! However, it turns out that this code is clearly causing a problem. It appears that the model binder on the [HttpPost] method is actually updating the list that's bound to and changing the actual entry item in the list and setting its selected value. If you look at the code above I'm not setting the SelectListItem.Selected value anywhere - the only place this value can get set is through ModelBinding. Sure enough when stepping through the code I see that when an item is selected the actual model - model.CategoryList[x].Selected - reflects that. This is bad on several levels: First it's obviously affecting the application behavior - nobody wants to see their drop down list values jump all over the place randomly. But it's also a problem because the array is getting updated by multiple ASP.NET threads which likely would lead to odd crashes from time to time. Not good! In retrospect the modelbinding behavior makes perfect sense. The actual items and the Selected property is the ModelBinder's way of keeping track of one or more selected values. So while I assumed the list to be read-only, the ModelBinder is actually updating it on a post back producing the rather surprising results. Totally missed this during testing and is another one of those little - "Did you know?" moments. So, is there a way around this? Yes but it's maybe not quite obvious. I can't change the behavior of the ModelBinder, but I can certainly change the way that the list is generated. Rather than returning the cached list, I can return a brand new cloned list from the cached items like this:/// <summary> /// Returns a static category list that is cached /// </summary> /// <returns></returns> public static SelectListItem[] GetCachedCategoryList() { if (_CategoryList != null) { // Have to create new instances via projection // to avoid ModelBinding updates to affect this // globally return _CategoryList .Select(cat => new SelectListItem() { Value = cat.Value, Text = cat.Text }) .ToArray(); } …}  The key is that newly created instances of SelectListItems are returned not just filtered instances of the original list. The key here is 'new instances' so that the ModelBinding updates do not update the actual static instance. The code above uses LINQ and a projection into new SelectListItem instances to create this array of fresh instances. And this code works correctly - no more cross-talk between users. Unfortunately this code is also less efficient - it has to reselect the items and uses extra memory for the new array. Knowing what I know now I probably would have not cached the list and just take the hit to read from the database. If there is even a possibility of thread clashes I'm very wary of creating code like this. But since the method already exists and handles this load in one place this fix was easy enough to put in. Live and learn. It's little things like this that can cause some interesting head scratchers sometimes…© Rick Strahl, West Wind Technologies, 2005-2012Posted in MVC  ASP.NET  .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Wishful Thinking: Why can't HTML fix Script Attacks at the Source?

  - by Rick Strahl

  The Web can be an evil place, especially if you're a Web Developer blissfully unaware of Cross Site Script Attacks (XSS). Even if you are aware of XSS in all of its insidious forms, it's extremely complex to deal with all the issues if you're taking user input and you're actually allowing users to post raw HTML into an application. I'm dealing with this again today in a Web application where legacy data contains raw HTML that has to be displayed and users ask for the ability to use raw HTML as input for listings. The first line of defense of course is: Just say no to HTML input from users. If you don't allow HTML input directly and use HTML Encoding (HttyUtility.HtmlEncode() in .NET or using standard ASP.NET MVC output @Model.Content) you're fairly safe at least from the HTML input provided. Both WebForms and Razor support HtmlEncoded content, although Razor makes it the default. In Razor the default @ expression syntax:@Model.UserContent automatically produces HTML encoded content - you actually have to go out of your way to create raw HTML content (safe by default) using @Html.Raw() or the HtmlString class. In Web Forms (V4) you can use:<%: Model.UserContent %> or if you're using a version prior to 4.0:<%= HttpUtility.HtmlEncode(Model.UserContent) %> This works great as a hedge against embedded <script> tags and HTML markup as any HTML is turned into text that displays as HTML but doesn't render the HTML. But it turns any embedded HTML markup tags into plain text. If you need to display HTML in raw form with the markup tags rendering based on user input this approach is worthless. If you do accept HTML input and need to echo the rendered HTML input back, the task of cleaning up that HTML is a complex task. In the projects I work on, customers are frequently asking for the ability to post raw HTML quite frequently.  Almost every app that I've built where there's document content from users we start out with text only input - possibly using something like MarkDown - but inevitably users want to just post plain old HTML they created in some other rich editing application. See this a lot with realtors especially who often want to reuse their postings easily in multiple places. In my work this is a common problem I need to deal with and I've tried dozens of different methods from sanitizing, simple rejection of input to custom markup schemes none of which have ever felt comfortable to me. They work in a half assed, hacked together sort of way but I always live in fear of missing something vital which is *really easy to do*. My Wishlist Item: A <restricted> tag in HTML Let me dream here for a second on how to address this problem. It seems to me the easiest place where this can be fixed is: In the browser. Browsers are actually executing script code so they have a lot of control over the script code that resides in a page. What if there was a way to specify that you want to turn off script code for a block of HTML? The main issue when dealing with HTML raw input isn't that we as developers are unaware of the implications of user input, but the fact that we sometimes have to display raw HTML input the user provides. So the problem markup is usually isolated in only a very specific part of the document. So, what if we had a way to specify that in any given HTML block, no script code could execute by wrapping it into a tag that disables all script functionality in the browser? This would include <script> tags and any document script attributes like onclick, onfocus etc. and potentially also disallow things like iFrames that can potentially be scripted from the within the iFrame's target. I'd like to see something along these lines:<article> <restricted allowscripts="no" allowiframes="no"> <div>Some content</div> <script>alert('go ahead make my day, punk!");</script> <div onfocus="$.getJson('http://evilsite.com/')">more content</div> </restricted> </article> A tag like this would basically disallow all script code from firing from any HTML that's rendered within it. You'd use this only on code that you actually render from your data only and only if you are dealing with custom data. So something like this:<article> <restricted> @Html.Raw(Model.UserContent) </restricted> </article> For browsers this would actually be easy to intercept. They render the DOM and control loading and execution of scripts that are loaded through it. All the browser would have to do is suspend execution of <script> tags and not hookup any event handlers defined via markup in this block. Given all the crazy XSS attacks that exist and the prevalence of this problem this would go a long way towards preventing at least coded script attacks in the DOM. And it seems like a totally doable solution that wouldn't be very difficult to implement by vendors. There would also need to be some logic in the parser to not allow an </restricted> or <restricted> tag into the content as to short-circuit the rstricted section (per James Hart's comment). I'm sure there are other issues to consider as well that I didn't think of in my off-the-back-of-a-napkin concept here but the idea overall seems worth consideration I think. Without code running in a user supplied HTML block it'd be pretty hard to compromise a local HTML document and pass information like Cookies to a server. Or even send data to a server period. Short of an iFrame that can access the parent frame (which is another restriction that should be available on this <restricted> tag) that could potentially communicate back, there's not a lot a malicious site could do. The HTML could still 'phone home' via image links and href links potentially and basically say this site was accessed, but without the ability to run script code it would be pretty tough to pass along critical information to the server beyond that. Ahhhh… one can dream… Not holding my breath of course. The design by committee that is the W3C can't agree on anything in timeframes measured less than decades, but maybe this is one place where browser vendors can actually step up the pressure. This is something in their best interest to reduce the attack surface for vulnerabilities on their browser platforms significantly. Several people commented on Twitter today that there isn't enough discussion on issues like this that address serious needs in the web browser space. Realistically security has to be a number one concern with Web applications in general - there isn't a Web app out there that is not vulnerable. And yet nothing has been done to address these security issues even though there might be relatively easy solutions to make this happen. It'll take time, and it's probably not going to happen in our lifetime, but maybe this rambling thought sparks some ideas on how this sort of restriction can get into browsers in some way in the future.© Rick Strahl, West Wind Technologies, 2005-2012Posted in ASP.NET  HTML5  HTML  Security   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Make your CHM Help Files show HTML5 and CSS3 content

  - by Rick Strahl

  The HTML Help 1.0 specification aka CHM files, is pretty old. In fact, it's practically ancient as it was introduced in 1997 when Internet Explorer 4 was introduced. Html Help 1.0 is basically a completely HTML based Help system that uses a Help Viewer that internally uses Internet Explorer to render the HTML Help content. Because of its use of the Internet Explorer shell for rendering there were many security issues in the past, which resulted in locking down of the Web Browser control in Windows and also the Help Engine which caused some unfortunate side effects. Even so, CHM continues to be a popular help format because it is very easy to produce content for it, using plain HTML and because it works with many Windows application platforms out of the box. While there have been various attempts to replace CHM help files CHM files still seem to be a popular choice for many applications to display their help systems. The biggest alternative these days is no system based help at all, but links to online documentation. For Windows apps though it's still very common to see CHM help files and there are still a ton of CHM help out there and lots of tools (including our own West Wind Html Help Builder) that produce output for CHM files as well as Web output. Image is Everything and you ain't got it! One problem with the CHM engine is that it's stuck with an ancient Internet Explorer version for rendering. For example if you have help content that uses HTML5 or CSS3 content you might have an HTML Help topic like the following shown here in a full Web Browser instance of Internet Explorer: The page clearly uses some CSS3 features like rounded corners and box shadows that are rendered using plain CSS 3 features. Note that I used Internet Explorer on purpose here to demonstrate that IE9 on Windows 7 can properly render this content using some of the new features of CSS, but the same is true for all other recent versions of the major browsers (FireFox 3.1+, Safari 4.5+, WebKit 9+ etc.). Unfortunately if you take this nice and simple CSS3 content and run it through the HTML Help compiler to produce a CHM file the resulting output on the same machine looks a bit less flashy: All the CSS3 styling is gone and although the page display and functionality still works, but all the extra styling features are gone. This even though I am running this on a Windows 7 machine that has IE9 that should be able to render these CSS features. Bummer. Web Browser Control - perpetually stuck in IE 7 Mode The problem is the Web Browser/Shell Components in Windows. This component is and has been part of Windows for as long as Internet Explorer has been around, but the Web Browser control hasn't kept up with the latest versions of IE. In a nutshell the control is stuck in IE7 rendering mode for engine compatibility reasons by default. However, there is at least one way to fix this explicitly using Registry keys on a per application basis. The key point from that blog article is that you can override the IE rendering engine for a particular executable by setting one (or more) registry flags that tell the Windows Shell which version of the Internet Explorer rendering engine to load. An application that wishes to use a more recent version of Internet Explorer can then register itself during installation for the specific IE version desired and from then on the application will use that version of the Web Browser component. If the application is older than the specified version it falls back to the default version (IE 7 rendering). Forcing CHM files to display with IE9 (or later) Rendering Knowing that we can force the IE usage for a given process it's also possible to affect the CHM rendering by setting same keys on the executable that's hosting the CHM file. What that executable file is depends on the type of application as there are a number of ways that can launch the help engine. hh.exeThe standalone Windows CHM Help Viewer that launches when you launch a CHM from Windows Explorer. You can manually add hh.exe to the registry keys. YourApplication.exeIf you're using .NET or any tool that internally uses the hhControl ActiveX control to launch help content your application is your host. You should add your application's exe to the registry during application startup. foxhhelp9.exeIf you're building a FoxPro application that uses the built-in help features, foxhhelp9.exe is used to actually host the help controls. Make sure to add this executable to the registry. What to set You can configure the Internet Explorer version used for an application in the registry by specifying the executable file name and a value that specifies the IE version desired. There are two different sets of keys for 32 bit and 64 bit applications. 32 bit only or 64 bit: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\MAIN\FeatureControl\FEATURE_BROWSER_EMULATION Value Key: hh.exe 32 bit on 64 bit machine: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Internet Explorer\MAIN\FeatureControl\FEATURE_BROWSER_EMULATION Value Key: hh.exe Note that it's best to always set both values ideally when you install your application so it works regardless of which platform you run on. The value specified is a DWORD value and the interesting values are decimal 9000 for IE9 rendering mode depending on !DOCTYPE settings or 9999 for IE 9 standards mode always. You can use the same logic for 8000 and 8888 for IE8 and the final value of 7000 for IE7 (one has to wonder what they're going todo for version 10 to perpetuate that pattern). I think 9000 is the value you'd most likely want to use. 9000 means that IE9 will be used for rendering but unless the right doctypes are used (XHTML and HTML5 specifically) IE will still fall back into quirks mode as needed. This should allow existing pages to continue to use the fallback engine while new pages that have the proper HTML doctype set can take advantage of the newest features. Here's an example of how I set the registry keys in my Tarma Installmate registry configuration: Note that I set all three values both under the Software and Wow6432Node keys so that this works regardless of where these EXEs are launched from. Even though all apps are 32 bit apps, the 64 bit (the default one shown selected) key is often used. So, now once I've set the registry key for hh.exe I can now launch my CHM help file from Explorer and see the following CSS3 IE9 rendered display: Summary It sucks that we have to go through all these hoops to get what should be natural behavior for an application to support the latest features available on a system. But it shouldn't be a surprise - the Windows Help team (if there even is such a thing) has not been known for forward looking technologies. It's a pretty big hassle that we have to resort to setting registry keys in order to get the Web Browser control and the internal CHM engine to render itself properly but at least it's possible to make it work after all. Using this technique it's possible to ship an application with a help file and allow your CHM help to display with richer CSS markup and correct rendering using the stricter and more consistent XHTML or HTML5 doctypes. If you provide both Web help and in-application help (and why not if you're building from a single source) you now can side step the issue of your customers asking: Why does my help file look so much shittier than the online help… No more!© Rick Strahl, West Wind Technologies, 2005-2012Posted in HTML5  Help  Html Help Builder  Internet Explorer  Windows   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Dynamic Types and DynamicObject References in C#

  - by Rick Strahl

  I've been working a bit with C# custom dynamic types for several customers recently and I've seen some confusion in understanding how dynamic types are referenced. This discussion specifically centers around types that implement IDynamicMetaObjectProvider or subclass from DynamicObject as opposed to arbitrary type casts of standard .NET types. IDynamicMetaObjectProvider types  are treated special when they are cast to the dynamic type. Assume for a second that I've created my own implementation of a custom dynamic type called DynamicFoo which is about as simple of a dynamic class that I can think of:public class DynamicFoo : DynamicObject { Dictionary<string, object> properties = new Dictionary<string, object>(); public string Bar { get; set; } public DateTime Entered { get; set; } public override bool TryGetMember(GetMemberBinder binder, out object result) { result = null; if (!properties.ContainsKey(binder.Name)) return false; result = properties[binder.Name]; return true; } public override bool TrySetMember(SetMemberBinder binder, object value) { properties[binder.Name] = value; return true; } } This class has an internal dictionary member and I'm exposing this dictionary member through a dynamic by implementing DynamicObject. This implementation exposes the properties dictionary so the dictionary keys can be referenced like properties (foo.NewProperty = "Cool!"). I override TryGetMember() and TrySetMember() which are fired at runtime every time you access a 'property' on a dynamic instance of this DynamicFoo type. Strong Typing and Dynamic Casting I now can instantiate and use DynamicFoo in a couple of different ways: Strong TypingDynamicFoo fooExplicit = new DynamicFoo(); var fooVar = new DynamicFoo(); These two commands are essentially identical and use strong typing. The compiler generates identical code for both of them. The var statement is merely a compiler directive to infer the type of fooVar at compile time and so the type of fooExplicit is DynamicFoo, just like fooExplicit. This is very static - nothing dynamic about it - and it completely ignores the IDynamicMetaObjectProvider implementation of my class above as it's never used. Using either of these I can access the native properties:DynamicFoo fooExplicit = new DynamicFoo();// static typing assignmentsfooVar.Bar = "Barred!"; fooExplicit.Entered = DateTime.Now; // echo back static values Console.WriteLine(fooVar.Bar); Console.WriteLine(fooExplicit.Entered); but I have no access whatsoever to the properties dictionary. Basically this creates a strongly typed instance of the type with access only to the strongly typed interface. You get no dynamic behavior at all. The IDynamicMetaObjectProvider features don't kick in until you cast the type to dynamic. If I try to access a non-existing property on fooExplicit I get a compilation error that tells me that the property doesn't exist. Again, it's clearly and utterly non-dynamic. Dynamicdynamic fooDynamic = new DynamicFoo(); fooDynamic on the other hand is created as a dynamic type and it's a completely different beast. I can also create a dynamic by simply casting any type to dynamic like this:DynamicFoo fooExplicit = new DynamicFoo(); dynamic fooDynamic = fooExplicit; Note that dynamic typically doesn't require an explicit cast as the compiler automatically performs the cast so there's no need to use as dynamic. Dynamic functionality works at runtime and allows for the dynamic wrapper to look up and call members dynamically. A dynamic type will look for members to access or call in two places: Using the strongly typed members of the object Using theIDynamicMetaObjectProvider Interface methods to access members So rather than statically linking and calling a method or retrieving a property, the dynamic type looks up - at runtime  - where the value actually comes from. It's essentially late-binding which allows runtime determination what action to take when a member is accessed at runtime *if* the member you are accessing does not exist on the object. Class members are checked first before IDynamicMetaObjectProvider interface methods are kick in. All of the following works with the dynamic type:dynamic fooDynamic = new DynamicFoo(); // dynamic typing assignments fooDynamic.NewProperty = "Something new!"; fooDynamic.LastAccess = DateTime.Now; // dynamic assigning static properties fooDynamic.Bar = "dynamic barred"; fooDynamic.Entered = DateTime.Now; // echo back dynamic values Console.WriteLine(fooDynamic.NewProperty); Console.WriteLine(fooDynamic.LastAccess); Console.WriteLine(fooDynamic.Bar); Console.WriteLine(fooDynamic.Entered); The dynamic type can access the native class properties (Bar and Entered) and create and read new ones (NewProperty,LastAccess) all using a single type instance which is pretty cool. As you can see it's pretty easy to create an extensible type this way that can dynamically add members at runtime dynamically. The Alter Ego of IDynamicObject The key point here is that all three statements - explicit, var and dynamic - declare a new DynamicFoo(), but the dynamic declaration results in completely different behavior than the first two simply because the type has been cast to dynamic. Dynamic binding means that the type loses its typical strong typing, compile time features. You can see this easily in the Visual Studio code editor. As soon as you assign a value to a dynamic you lose Intellisense and you see which means there's no Intellisense and no compiler type checking on any members you apply to this instance. If you're new to the dynamic type it might seem really confusing that a single type can behave differently depending on how it is cast, but that's exactly what happens when you use a type that implements IDynamicMetaObjectProvider. Declare the type as its strong type name and you only get to access the native instance members of the type. Declare or cast it to dynamic and you get dynamic behavior which accesses native members plus it uses IDynamicMetaObjectProvider implementation to handle any missing member definitions by running custom code. You can easily cast objects back and forth between dynamic and the original type:dynamic fooDynamic = new DynamicFoo(); fooDynamic.NewProperty = "New Property Value"; DynamicFoo foo = fooDynamic; foo.Bar = "Barred"; Here the code starts out with a dynamic cast and a dynamic assignment. The code then casts back the value to the DynamicFoo. Notice that when casting from dynamic to DynamicFoo and back we typically do not have to specify the cast explicitly - the compiler can induce the type so I don't need to specify as dynamic or as DynamicFoo. Moral of the Story This easy interchange between dynamic and the underlying type is actually super useful, because it allows you to create extensible objects that can expose non-member data stores and expose them as an object interface. You can create an object that hosts a number of strongly typed properties and then cast the object to dynamic and add additional dynamic properties to the same type at runtime. You can easily switch back and forth between the strongly typed instance to access the well-known strongly typed properties and to dynamic for the dynamic properties added at runtime. Keep in mind that dynamic object access has quite a bit of overhead and is definitely slower than strongly typed binding, so if you're accessing the strongly typed parts of your objects you definitely want to use a strongly typed reference. Reserve dynamic for the dynamic members to optimize your code. The real beauty of dynamic is that with very little effort you can build expandable objects or objects that expose different data stores to an object interface. I'll have more on this in my next post when I create a customized and extensible Expando object based on DynamicObject.© Rick Strahl, West Wind Technologies, 2005-2012Posted in CSharp  .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Replacing jQuery.live() with jQuery.on()

  - by Rick Strahl

  jQuery 1.9 and 1.10 have introduced a host of changes, but for the most part these changes are mostly transparent to existing application usage of jQuery. After spending some time last week with a few of my projects and going through them with a specific eye for jQuery failures I found that for the most part there wasn't a big issue. The vast majority of code continues to run just fine with either 1.9 or 1.10 (which are supposed to be in sync but with 1.10 removing support for legacy Internet Explorer pre-9.0 versions). However, one particular change in the new versions has caused me quite a bit of update trouble, is the removal of the jQuery.live() function. This is my own fault I suppose - .live() has been deprecated for a while, but with 1.9 and later it was finally removed altogether from jQuery. In the past I had quite a bit of jQuery code that used .live() and it's one of the things that's holding back my upgrade process, although I'm slowly cleaning up my code and switching to the .on() function as the replacement. jQuery.live() jQuery.live() was introduced a long time ago to simplify handling events on matched elements that exist currently on the document and those that are are added in the future and also match the selector. jQuery uses event bubbling, special event binding, plus some magic using meta data attached to a parent level element to check and see if the original target event element matches the selected selected elements (for more info see Elijah Manor's comment below). An Example Assume a list of items like the following in HTML for example and further assume that the items in this list can be appended to at a later point. In this app there's a smallish initial list that loads to start, and as the user scrolls towards the end of the initial small list more items are loaded dynamically and added to the list.<div id="PostItemContainer" class="scrollbox"> <div class="postitem" data-id="4z6qhomm"> <div class="post-icon"></div> <div class="postitemheader"><a href="show/4z6qhomm" target="Content">1999 Buick Century For Sale!</a></div> <div class="postitemprice rightalign">$ 3,500 O.B.O.</div> <div class="smalltext leftalign">Jun. 07 @ 1:06am</div> <div class="post-byline">- Vehicles - Automobiles</div> </div> <div class="postitem" data-id="2jtvuu17"> <div class="postitemheader"><a href="show/2jtvuu17" target="Content">Toyota VAN 1987</a></div> <div class="postitemprice rightalign">$950</div> <div class="smalltext leftalign">Jun. 07 @ 12:29am</div> <div class="post-byline">- Vehicles - Automobiles</div> </div> … </div> With the jQuery.live() function you could easily select elements and hook up a click handler like this:$(".postitem").live("click", function() {...}); Simple and perfectly readable. The behavior of the .live handler generally was the same as the corresponding simple event handlers like .click(), except that you have to explicitly name the event instead of using one of the methods. Re-writing with jQuery.on() With .live() removed in 1.9 and later we have to re-write .live() code above with an alternative. The jQuery documentation points you at the .on() or .delegate() functions to update your code. jQuery.on() is a more generic event handler function, and it's what jQuery uses internally to map the high level event functions like .click(),.change() etc. that jQuery exposes. Using jQuery.on() however is not a one to one replacement of the .live() function. While .on() can handle events directly and use the same syntax as .live() did, you'll find if you simply switch out .live() with .on() that events on not-yet existing elements will not fire. IOW, the key feature of .live() is not working. You can use .on() to get the desired effect however, but you have to change the syntax to explicitly handle the event you're interested in on the container and then provide a filter selector to specify which elements you are actually interested in for handling the event for. Sounds more complicated than it is and it's easier to see with an example. For the list above hooking .postitem clicks, using jQuery.on() looks like this:$("#PostItemContainer").on("click", ".postitem", function() {...}); You specify a container that can handle the .click event and then provide a filter selector to find the child elements that trigger the  the actual event. So here #PostItemContainer contains many .postitems, whose click events I want to handle. Any container will do including document, but I tend to use the container closest to the elements I actually want to handle the events on to minimize the event bubbling that occurs to capture the event. With this code I get the same behavior as with .live() and now as new .postitem elements are added the click events are always available. Sweet. Here's the full event signature for the .on() function: .on( events [, selector ] [, data ], handler(eventObject) ) Note that the selector is optional - if you omit it you essentially create a simple event handler that handles the event directly on the selected object. The filter/child selector required if you want life-like - uh, .live() like behavior to happen. While it's a bit more verbose than what .live() did, .on() provides the same functionality by being more explicit on what your parent container for trapping events is. .on() is good Practice even for ordinary static Element Lists As a side note, it's a good practice to use jQuery.on() or jQuery.delegate() for events in most cases anyway, using this 'container event trapping' syntax. That's because rather than requiring lots of event handlers on each of the child elements (.postitem in the sample above), there's just one event handler on the container, and only when clicked does jQuery drill down to find the matching filter element and tries to match it to the originating element. In the early days of jQuery I used manually build handlers that did this and manually drilled from the event object into the originalTarget to determine if it's a matching element. With later versions of jQuery the various event functions in jQuery essentially provide this functionality out of the box with functions like .on() and .delegate(). All of this is nothing new, but I thought I'd write this up because I have on a few occasions forgotten what exactly was needed to replace the many .live() function calls that litter my code - especially older code. This will be a nice reminder next time I have a memory blank on this topic. And maybe along the way I've helped one or two of you as well to clean up your .live() code…© Rick Strahl, West Wind Technologies, 2005-2013Posted in jQuery   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• .NET 4.5 is an in-place replacement for .NET 4.0

  - by Rick Strahl

  With the betas for .NET 4.5 and Visual Studio 11 and Windows 8 shipping many people will be installing .NET 4.5 and hacking away on it. There are a number of great enhancements that are fairly transparent, but it's important to understand what .NET 4.5 actually is in terms of the CLR running on your machine. When .NET 4.5 is installed it effectively replaces .NET 4.0 on the machine. .NET 4.0 gets overwritten by a new version of .NET 4.5 which - according to Microsoft - is supposed to be 100% backwards compatible. While 100% backwards compatible sounds great, we all know that 100% is a hard number to hit, and even the aforementioned blog post at the Microsoft site acknowledges this. But there's so much more than backwards compatibility that makes this awkward at best and confusing at worst. What does ‘Replacement’ mean? When you install .NET 4.5 your .NET 4.0 assemblies in the \Windows\.NET Framework\V4.0.30319 are overwritten with a new set of assemblies. You end up with overwritten assemblies as well as a bunch of new ones (like the new System.Net.Http assemblies for example). The following screen shot demonstrates system.dll on my test machine (left) running .NET 4.5 on the right and my production laptop running stock .NET 4.0 (right):   Clearly they are different files with a difference in file sizes (interesting that the 4.5 version is actually smaller). That’s not all. If you actually query the runtime version when .NET 4.5 is installed with with Environment.Version you still get: 4.0.30319 If you open the properties of System.dll assembly in .NET 4.5 you'll also see: Notice that the file version is also left at 4.0.xxx. There are differences in build numbers: .NET 4.0 shows 261 and the current .NET 4.5 beta build is 17379. I suppose you can use assume a build number greater than 17000 is .NET 4.5, but that's pretty hokey to say the least. There’s no easy or obvious way to tell whether you are running on 4.0 or 4.5 – to the application they appear to be the same runtime version. And that is what Microsoft intends here. .NET 4.5 is intended as an in-place upgrade. Compile to 4.5 run on 4.0 – not quite! You can compile an application for .NET 4.5 and run it on the 4.0 runtime – that is until you hit a new feature that doesn’t exist on 4.0. At which point the app bombs at runtime. Say you write some code that is mostly .NET 4.0, but only has a few of the new features of .NET 4.5 like aync/await buried deep in the bowels of the application where it only fires occasionally. .NET will happily start your application and run everything 4.0 fine, until it hits that 4.5 code – and then crash unceremoniously at runtime. Oh joy! You can .NET 4.0 applications on .NET 4.5 of course and that should work without much fanfare. Different than .NET 3.0/3.5 Note that this in-place replacement is very different from the side by side installs of .NET 2.0 and 3.0/3.5 which all ran on the 2.0 version of the CLR. The two 3.x versions were basically library enhancements on top of the core .NET 2.0 runtime. Both versions ran under the .NET 2.0 runtime which wasn’t changed (other than for security patches and bug fixes) for the whole 3.x cycle. The 4.5 update instead completely replaces the .NET 4.0 runtime and leaves the actual version number set at v4.0.30319. When you build a new project with Visual Studio 2011, you can still target .NET 4.0 or you can target .NET 4.5. But you are in effect referencing the same set of assemblies for both regardless which version you use. What's different is the compiler used to compile and link your code so compiling with .NET 4.0 gives you just the subset of the functionality that is available in .NET 4.0, but when you use the 4.5 compiler you get the full functionality of what’s actually available in the assemblies and extra libraries. It doesn’t look like you will be able to use Visual Studio 2010 to develop .NET 4.5 applications. Good news – Bad news Microsoft is trying hard to experiment with every possible permutation of releasing new versions of the .NET framework apparently. No two updates have been the same. Clearly updating to a full new version of .NET (ie. .NET 2.0, 4.0 and at some point 5.0 runtimes) has its own set of challenges, but doing an in-place update of the runtime and then not even providing a good way to tell which version is installed is pretty whacky even by Microsoft’s standards. Especially given that .NET 4.5 includes a fairly significant update with all the aysnc functionality baked into the runtime. Most of the IO APIs have been updated to support task based async operation which significantly affects many existing APIs. To make things worse .NET 4.5 will be the initial version of .NET that ships with Windows 8 so it will be with us for a long time to come unless Microsoft finally decides to push .NET versions onto Windows machines as part of system upgrades (which currently doesn’t happen). This is the same story we had when Vista launched with .NET 3.0 which was a minor version that quickly was replaced by 3.5 which was more long lived and practical. People had enough problems dealing with the confusing versioning of the 3.x versions which ran on .NET 2.0. I can’t count the amount support calls and questions I’ve fielded because people couldn’t find a .NET 3.5 entry in the IIS version dialog. The same is likely to happen with .NET 4.5. It’s all well and good when we know that .NET 4.5 is an in-place replacement, but administrators and IT folks not intimately familiar with .NET are unlikely to understand this nuance and end up thoroughly confused which version is installed. It’s hard for me to see any upside to an in-place update and I haven’t really seen a good explanation of why this approach was decided on. Sure if the version stays the same existing assembly bindings don’t break so applications can stay running through an update. I suppose this is useful for some component vendors and strongly signed assemblies in corporate environments. But seriously, if you are going to throw .NET 4.5 into the mix, who won’t be recompiling all code and thoroughly test that code to work on .NET 4.5? A recompile requirement doesn’t seem that serious in light of a major version upgrade.  Resources http://blogs.msdn.com/b/dotnet/archive/2011/09/26/compatibility-of-net-framework-4-5.aspx http://www.devproconnections.com/article/net-framework/net-framework-45-versioning-faces-problems-141160© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• FAQ: GridView Calculation with JavaScript

  - by Vincent Maverick Durano

  In my previous post I wrote a simple demo on how to Calculate Totals in GridView and Display it in the Footer. Basically what it does is it calculates the total amount by typing into the TextBox and display the grand total in the footer of the GridView and basically it was a server side implemenation.  Many users in the forums are asking how to do the same thing without postbacks and how to calculate both amount and total amount together. In this post I will demonstrate how to do this using JavaScript. To get started let's go ahead and set up the form. Just for the simplicity of this demo I just set up the form like this:   <asp:gridview ID="GridView1" runat="server" ShowFooter="true" AutoGenerateColumns="false"> <Columns> <asp:BoundField DataField="RowNumber" HeaderText="Row Number" /> <asp:BoundField DataField="Description" HeaderText="Item Description" /> <asp:TemplateField HeaderText="Item Price"> <ItemTemplate> <asp:Label ID="LBLPrice" runat="server" Text='<%# Eval("Price") %>'></asp:Label> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Quantity"> <ItemTemplate> <asp:TextBox ID="TXTQty" runat="server"></asp:TextBox> </ItemTemplate> <FooterTemplate> <b>Total Amount:</b> </FooterTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Sub-Total"> <ItemTemplate> <asp:Label ID="LBLSubTotal" runat="server"></asp:Label> </ItemTemplate> <FooterTemplate> <asp:Label ID="LBLTotal" runat="server" ForeColor="Green"></asp:Label> </FooterTemplate> </asp:TemplateField> </Columns> </asp:gridview>   As you can see there's no fancy about the mark up above. It just a standard GridView with BoundFields and TemplateFields on it. Now just for the purpose of this demo I just use a dummy data for populating the GridView. Here's the code below:   public partial class GridCalculation : System.Web.UI.Page { private void BindDummyDataToGrid() { DataTable dt = new DataTable(); DataRow dr = null; dt.Columns.Add(new DataColumn("RowNumber", typeof(string))); dt.Columns.Add(new DataColumn("Description", typeof(string))); dt.Columns.Add(new DataColumn("Price", typeof(string))); dr = dt.NewRow(); dr["RowNumber"] = 1; dr["Description"] = "Nike"; dr["Price"] = "1000"; dt.Rows.Add(dr); dr = dt.NewRow(); dr["RowNumber"] = 2; dr["Description"] = "Converse"; dr["Price"] = "800"; dt.Rows.Add(dr); dr = dt.NewRow(); dr["RowNumber"] = 3; dr["Description"] = "Adidas"; dr["Price"] = "500"; dt.Rows.Add(dr); dr = dt.NewRow(); dr["RowNumber"] = 4; dr["Description"] = "Reebok"; dr["Price"] = "750"; dt.Rows.Add(dr); dr = dt.NewRow(); dr["RowNumber"] = 5; dr["Description"] = "Vans"; dr["Price"] = "1100"; dt.Rows.Add(dr); dr = dt.NewRow(); dr["RowNumber"] = 6; dr["Description"] = "Fila"; dr["Price"] = "200"; dt.Rows.Add(dr); //Bind the Gridview GridView1.DataSource = dt; GridView1.DataBind(); } protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { BindDummyDataToGrid(); } } }   Now try to run the page. The output should look something like below: The Client-Side Calculation Here's the code for the GridView calculation:   <script type="text/javascript"> function CalculateTotals() { var gv = document.getElementById("<%= GridView1.ClientID %>"); var tb = gv.getElementsByTagName("input"); var lb = gv.getElementsByTagName("span"); var sub = 0; var total = 0; var indexQ = 1; var indexP = 0; for (var i = 0; i < tb.length; i++) { if (tb[i].type == "text") { sub = parseFloat(lb[indexP].innerHTML) * parseFloat(tb[i].value); if (isNaN(sub)) { lb[i + indexQ].innerHTML = ""; sub = 0; } else { lb[i + indexQ].innerHTML = sub; } indexQ++; indexP = indexP + 2; total += parseFloat(sub); } } lb[lb.length -1].innerHTML = total; } </script>   The code above calculates the sub-total by multiplying the price and the quantity and at the same time calculates the total amount  by adding the sub-total values. Now you can simply call the JavaScript function above like this:   <ItemTemplate> <asp:TextBox ID="TXTQty" runat="server" onkeyup="CalculateTotals();"></asp:TextBox> </ItemTemplate>   Running the code above will display something like below: That's it! I hope someone find this post useful! Technorati Tags: ASP.NET,JavaScript,GridView,TipsTricks

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• FAQ: GridView Calculation with JavaScript - Formatting and Validation

  - by Vincent Maverick Durano

  In my previous post here we've talked about how to calculate the sub-totals and grand total in GridView using JavaScript. In this post I'm going take more step further and will demonstrate how are we going to format the totals into a currency and how to validate the input that would only allow you to enter a whole number in the quantity TextBox. Here are the code blocks below: ASPX Source:   <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title></title> <script type="text/javascript"> function CalculateTotals() { var gv = document.getElementById("<%= GridView1.ClientID %>"); var tb = gv.getElementsByTagName("input"); var lb = gv.getElementsByTagName("span"); var sub = 0; var total = 0; var indexQ = 1; var indexP = 0; var price = 0; for (var i = 0; i < tb.length; i++) { if (tb[i].type == "text") { ValidateNumber(tb[i]); price = lb[indexP].innerHTML.replace("$", "").replace(",", ""); sub = parseFloat(price) * parseFloat(tb[i].value); if (isNaN(sub)) { lb[i + indexQ].innerHTML = "0.00"; sub = 0; } else { lb[i + indexQ].innerHTML = FormatToMoney(sub, "$", ",", "."); ; } indexQ++; indexP = indexP + 2; total += parseFloat(sub); } } lb[lb.length - 1].innerHTML = FormatToMoney(total, "$", ",", "."); } function ValidateNumber(o) { if (o.value.length > 0) { o.value = o.value.replace(/[^\d]+/g, ''); //Allow only whole numbers } } function isThousands(position) { if (Math.floor(position / 3) * 3 == position) return true; return false; }; function FormatToMoney(theNumber, theCurrency, theThousands, theDecimal) { var theDecimalDigits = Math.round((theNumber * 100) - (Math.floor(theNumber) * 100)); theDecimalDigits = "" + (theDecimalDigits + "0").substring(0, 2); theNumber = "" + Math.floor(theNumber); var theOutput = theCurrency; for (x = 0; x < theNumber.length; x++) { theOutput += theNumber.substring(x, x + 1); if (isThousands(theNumber.length - x - 1) && (theNumber.length - x - 1 != 0)) { theOutput += theThousands; }; }; theOutput += theDecimal + theDecimalDigits; return theOutput; } </script> </head> <body> <form id="form1" runat="server"> <asp:gridview ID="GridView1" runat="server" ShowFooter="true" AutoGenerateColumns="false"> <Columns> <asp:BoundField DataField="RowNumber" HeaderText="Row Number" /> <asp:BoundField DataField="Description" HeaderText="Item Description" /> <asp:TemplateField HeaderText="Item Price"> <ItemTemplate> <asp:Label ID="LBLPrice" runat="server" Text='<%# Eval("Price","{0:C}") %>'></asp:Label> </ItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Quantity"> <ItemTemplate> <asp:TextBox ID="TXTQty" runat="server" onkeyup="CalculateTotals();"></asp:TextBox> </ItemTemplate> <FooterTemplate> <b>Total Amount:</b> </FooterTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Sub-Total"> <ItemTemplate> <asp:Label ID="LBLSubTotal" runat="server" ForeColor="Green" Text="0.00"></asp:Label> </ItemTemplate> <FooterTemplate> <asp:Label ID="LBLTotal" runat="server" ForeColor="Green" Font-Bold="true" Text="0.00"></asp:Label> </FooterTemplate> </asp:TemplateField> </Columns> </asp:gridview> </form> </body> </html> Code Behind Source:   public partial class GridCalculation : System.Web.UI.Page { private void BindDummyDataToGrid() { DataTable dt = new DataTable(); DataRow dr = null; dt.Columns.Add(new DataColumn("RowNumber", typeof(string))); dt.Columns.Add(new DataColumn("Description", typeof(string))); dt.Columns.Add(new DataColumn("Price", typeof(decimal))); dr = dt.NewRow(); dr["RowNumber"] = 1; dr["Description"] = "Nike"; dr["Price"] = "1000"; dt.Rows.Add(dr); dr = dt.NewRow(); dr["RowNumber"] = 2; dr["Description"] = "Converse"; dr["Price"] = "800"; dt.Rows.Add(dr); dr = dt.NewRow(); dr["RowNumber"] = 3; dr["Description"] = "Adidas"; dr["Price"] = "500"; dt.Rows.Add(dr); dr = dt.NewRow(); dr["RowNumber"] = 4; dr["Description"] = "Reebok"; dr["Price"] = "750"; dt.Rows.Add(dr); dr = dt.NewRow(); dr["RowNumber"] = 5; dr["Description"] = "Vans"; dr["Price"] = "1100"; dt.Rows.Add(dr); dr = dt.NewRow(); dr["RowNumber"] = 6; dr["Description"] = "Fila"; dr["Price"] = "200"; dt.Rows.Add(dr); //Bind the Gridview GridView1.DataSource = dt; GridView1.DataBind(); } protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { BindDummyDataToGrid(); } } } Running the code above will display something like this: On initial load After entering the quantity in the TextBox That's it! I hope someone find this post useful! Technorati Tags: ASP.NET,C#,ADO.NET,JavaScript,GridView

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• Using the HTML5 &lt;input type=&quot;file&quot; multiple=&quot;multiple&quot;&gt; Tag in ASP.NET

  - by Rick Strahl

  Per HTML5 spec the <input type="file" /> tag allows for multiple files to be picked from a single File upload button. This is actually a very subtle change that's very useful as it makes it much easier to send multiple files to the server without using complex uploader controls. Please understand though, that even though you can send multiple files using the <input type="file" /> tag, the process of how those files are sent hasn't really changed - there's still no progress information or other hooks that allow you to automatically make for a nicer upload experience without additional libraries or code. For that you will still need some sort of library (I'll post an example in my next blog post using plUpload). All the new features allow for is to make it easier to select multiple images from disk in one operation. Where you might have required many file upload controls before to upload several files, one File control can potentially do the job. How it works To create a file input box that allows with multiple file support you can simply do:<form method="post" enctype="multipart/form-data"> <label>Upload Images:</label> <input type="file" multiple="multiple" name="File1" id="File1" accept="image/*" /> <hr /> <input type="submit" id="btnUpload" value="Upload Images" /> </form> Now when the file open dialog pops up - depending on the browser and whether the browser supports it - you can pick multiple files. Here I'm using Firefox using the thumbnail preview I can easily pick images to upload on a form: Note that I can select multiple images in the dialog all of which get stored in the file textbox. The UI for this can be different in some browsers. For example Chrome displays 3 files selected as text next to the Browse… button when I choose three rather than showing any files in the textbox. Most other browsers display the standard file input box and display the multiple filenames as a comma delimited list in the textbox. Note that you can also specify the accept attribute in the <input> tag, which specifies a mime-type to specify what type of content to allow.Here I'm only allowing images (image/*) and the browser complies by just showing me image files to display. Likewise I could use text/* for all text formats registered on the machine or text/xml to only show XML files (which would include xml,xst,xsd etc.). Capturing Files on the Server with ASP.NET When you upload files to an ASP.NET server there are a couple of things to be aware of. When multiple files are uploaded from a single file control, they are assigned the same name. In other words if I select 3 files to upload on the File1 control shown above I get three file form variables named File1. This means I can't easily retrieve files by their name:HttpPostedFileBase file = Request.Files["File1"]; because there will be multiple files for a given name. The above only selects the first file. Instead you can only reliably retrieve files by their index. Below is an example I use in app to capture a number of images uploaded and store them into a database using a business object and EF 4.2.for (int i = 0; i < Request.Files.Count; i++) { HttpPostedFileBase file = Request.Files[i]; if (file.ContentLength == 0) continue; if (file.ContentLength > App.Configuration.MaxImageUploadSize) { ErrorDisplay.ShowError("File " + file.FileName + " is too large. Max upload size is: " + App.Configuration.MaxImageUploadSize); return View("UploadClassic",model); } var image = new ClassifiedsBusiness.Image(); var ms = new MemoryStream(16498); file.InputStream.CopyTo(ms); image.Entered = DateTime.Now; image.EntryId = model.Entry.Id; image.ContentType = "image/jpeg"; image.ImageData = ms.ToArray(); ms.Seek(0, SeekOrigin.Begin); // resize image if necessary and turn into jpeg Bitmap bmp = Imaging.ResizeImage(ms.ToArray(), App.Configuration.MaxImageWidth, App.Configuration.MaxImageHeight); ms.Close(); ms = new MemoryStream(); bmp.Save(ms,ImageFormat.Jpeg); image.ImageData = ms.ToArray(); bmp.Dispose(); ms.Close(); model.Entry.Images.Add(image); } This works great and also allows you to capture input from multiple input controls if you are dealing with browsers that don't support multiple file selections in the file upload control. The important thing here is that I iterate over the files by index, rather than using a foreach loop over the Request.Files collection. The files collection returns key name strings, rather than the actual files (who thought that was good idea at Microsoft?), and so that isn't going to work since you end up getting multiple keys with the same name. Instead a plain for loop has to be used to loop over all files. Another Option in ASP.NET MVC If you're using ASP.NET MVC you can use the code above as well, but you have yet another option to capture multiple uploaded files by using a parameter for your post action method.public ActionResult Save(HttpPostedFileBase[] file1) { foreach (var file in file1) { if (file.ContentLength < 0) continue; // do something with the file }} Note that in order for this to work you have to specify each posted file variable individually in the parameter list. This works great if you have a single file upload to deal with. You can also pass this in addition to your main model to separate out a ViewModel and a set of uploaded files:public ActionResult Edit(EntryViewModel model,HttpPostedFileBase[] uploadedFile) You can also make the uploaded files part of the ViewModel itself - just make sure you use the appropriate naming for the variable name in the HTML document (since there's Html.FileFor() extension). Browser Support You knew this was coming, right? The feature is really nice, but unfortunately not supported universally yet. Once again Internet Explorer is the problem: No shipping version of Internet Explorer supports multiple file uploads. IE10 supposedly will, but even IE9 does not. All other major browsers - Chrome, Firefox, Safari and Opera - support multi-file uploads in their latest versions. So how can you handle this? If you need to provide multiple file uploads you can simply add multiple file selection boxes and let people either select multiple files with a single upload file box or use multiples. Alternately you can do some browser detection and if IE is used simply show the extra file upload boxes. It's not ideal, but either one of these approaches makes life easier for folks that use a decent browser and leaves you with a functional interface for those that don't. Here's a UI I recently built as an alternate uploader with multiple file upload buttons: I say this is my 'alternate' uploader - for my primary uploader I continue to use an add-in solution. Specifically I use plUpload and I'll discuss how that's implemented in my next post. Although I think that plUpload (and many of the other packaged JavaScript upload solutions) are a better choice especially for large uploads, for simple one file uploads input boxes work well enough. The advantage of this solution is that it's very easy to handle on the server side. Any of the JavaScript controls require special handling for uploads which I'll also discuss in my next post.© Rick Strahl, West Wind Technologies, 2005-2012Posted in HTML5  ASP.NET  MVC   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Using Radio Button in GridView with Validation

  - by Vincent Maverick Durano

  A developer is asking how to select one radio button at a time if the radio button is inside the GridView.  As you may know setting the group name attribute of radio button will not work if the radio button is located within a Data Representation control like GridView. This because the radio button inside the gridview bahaves differentely. Since a gridview is rendered as table element , at run time it will assign different "name" to each radio button. Hence you are able to select multiple rows. In this post I'm going to demonstrate how select one radio button at a time in gridview and add a simple validation on it. To get started let's go ahead and fire up visual studio and the create a new web application / website project. Add a WebForm and then add gridview. The mark up would look something like this: <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" > <Columns> <asp:TemplateField> <ItemTemplate> <asp:RadioButton ID="rb" runat="server" /> </ItemTemplate> </asp:TemplateField> <asp:BoundField DataField="RowNumber" HeaderText="Row Number" /> <asp:BoundField DataField="Col1" HeaderText="First Column" /> <asp:BoundField DataField="Col2" HeaderText="Second Column" /> </Columns> </asp:GridView> Noticed that I've added a templatefield column so that we can add the radio button there. Also I have set up some BoundField columns and set the DataFields as RowNumber, Col1 and Col2. These columns are just dummy columns and i used it for the simplicity of this example. Now where these columns came from? These columns are created by hand at the code behind file of the ASPX. Here's the code below: private DataTable FillData() { DataTable dt = new DataTable(); DataRow dr = null; //Create DataTable columns dt.Columns.Add(new DataColumn("RowNumber", typeof(string))); dt.Columns.Add(new DataColumn("Col1", typeof(string))); dt.Columns.Add(new DataColumn("Col2", typeof(string))); //Create Row for each columns dr = dt.NewRow(); dr["RowNumber"] = 1; dr["Col1"] = "A"; dr["Col2"] = "B"; dt.Rows.Add(dr); dr = dt.NewRow(); dr["RowNumber"] = 2; dr["Col1"] = "AA"; dr["Col2"] = "BB"; dt.Rows.Add(dr); dr = dt.NewRow(); dr["RowNumber"] = 3; dr["Col1"] = "A"; dr["Col2"] = "B"; dt.Rows.Add(dr); dr = dt.NewRow(); dr["RowNumber"] = 4; dr["Col1"] = "A"; dr["Col2"] = "B"; dt.Rows.Add(dr); dr = dt.NewRow(); dr["RowNumber"] = 5; dr["Col1"] = "A"; dr["Col2"] = "B"; dt.Rows.Add(dr); return dt; } And here's the code for binding the GridView with the dummy data above. protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { GridView1.DataSource = FillData(); GridView1.DataBind(); } } Okay we have now a GridView data with a radio button on each row. Now lets go ahead and switch back to ASPX mark up. In this example I'm going to use a JavaScript for validating the radio button to select one radio button at a time. Here's the javascript code below: function CheckOtherIsCheckedByGVID(rb) { var isChecked = rb.checked; var row = rb.parentNode.parentNode; if (isChecked) { row.style.backgroundColor = '#B6C4DE'; row.style.color = 'black'; } var currentRdbID = rb.id; parent = document.getElementById("<%= GridView1.ClientID %>"); var items = parent.getElementsByTagName('input'); for (i = 0; i < items.length; i++) { if (items[i].id != currentRdbID && items[i].type == "radio") { if (items[i].checked) { items[i].checked = false; items[i].parentNode.parentNode.style.backgroundColor = 'white'; items[i].parentNode.parentNode.style.color = '#696969'; } } } } The function above sets the row of the current selected radio button's style to determine that the row is selected and then loops through the radio buttons in the gridview and then de-select the previous selected radio button and set the row style back to its default. You can then call the javascript function above at onlick event of radio button like below: <asp:RadioButton ID="rb" runat="server" onclick="javascript:CheckOtherIsCheckedByGVID(this);" /> Here's the output below: On Load: After Selecting a Radio Button: As you have noticed, on initial load there's no default selected radio in the GridView. Now let's add a simple validation for that. We will basically display an error message if a user clicks a button that triggers a postback without selecting  a radio button in the GridView. Here's the javascript for the validation: function ValidateRadioButton(sender, args) { var gv = document.getElementById("<%= GridView1.ClientID %>"); var items = gv.getElementsByTagName('input'); for (var i = 0; i < items.length ; i++) { if (items[i].type == "radio") { if (items[i].checked) { args.IsValid = true; return; } else { args.IsValid = false; } } } } The function above loops through the rows in gridview and find all the radio buttons within it. It will then check each radio button checked property. If a radio is checked then set IsValid to true else set it to false.  The reason why I'm using IsValid is because I'm using the ASP validator control for validation. Now add the following mark up below under the GridView declaration: <br /> <asp:Label ID="lblMessage" runat="server" /> <br /> <asp:Button ID="btn" runat="server" Text="POST" onclick="btn_Click" ValidationGroup="GroupA" /> <asp:CustomValidator ID="CustomValidator1" runat="server" ErrorMessage="Please select row in the grid." ClientValidationFunction="ValidateRadioButton" ValidationGroup="GroupA" style="display:none"></asp:CustomValidator> <asp:ValidationSummary ID="ValidationSummary1" runat="server" ValidationGroup="GroupA" HeaderText="Error List:" DisplayMode="BulletList" ForeColor="Red" /> And then at Button Click event add this simple code below just to test if  the validation works: protected void btn_Click(object sender, EventArgs e) { lblMessage.Text = "Postback at: " + DateTime.Now.ToString("hh:mm:ss tt"); } Here's the output below that you can see in the browser:   That's it! I hope someone find this post useful! Technorati Tags: ASP.NET,JavaScript,GridView

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• Fixing a SkyDrive Sync Disaster

  - by Rick Strahl

  For a few months I've been using SkyDrive to handle some basic synching tasks for a number of folders of mine. Specifically I've been dumping a few of my development folders into sky drive so I have a live running backup. It had been working just fine until about a week ago when something went awry. Badly! The idea is that the SkyDrive should sync files, but somewhere in its sync relationship it appears that SkyDrive got confused and assumed it needed to sync back older files to my local machine from the SkyDrive server. So rather than syncing my newer files to the server SkyDrive was pushing older files back to me. Because SkyDrive is so slow actually updating data it's not unusual for SkyDrive to be far behind in syncing and apparently some files were out of date by several months. Of course this is insidious because I didn't notice it for quite some time. I'd been happily working away on my files when a few days ago I noted a bunch of files with -RasXps (my machine name) popping up in various folders. At first I thought my Git repository was giving me a fit, but eventually realized that SkyDrive was actually pushing old files into my monitored folders. To be fair SkyDrive did make backups of the existing files, but by the time I caught it there were literally a few thousand files scattered on my machine that were now updated with old files from online. Here's what some of this looks like: If you look at the directory list you see a bunch of files with a -RasXps postfix appended to them. Those are the files that SkyDrive replaced and backed up on my machine. As you can see the backed up files are actually newer than the ones it pulled from the online SkyDrive. Unless I modified the files after they were updated they all were older than the existing local files. Not exactly how I imagined my synching would work. At first I started cleaning up this mess manually. In most cases the obvious solution was to simply delete the original file and replace with the -RasXps file, but not in all files. Some scrutiny was required and besides being a pain in the ass to rename files, quite frequently I had to dig out Beyond Compare to compare a few files where it wasn't quite clear what's wrong. I quickly realized that doing this by hand would be too hard for the large number of files that got hosed. Hacking together a small .NET Utility So, I figured the easiest way to tackle this is to write a small utility app that shows me all the mangled files that have backups, allows me to compare them and then quickly select and update them, removing the -RasXps file after choosing one of the two files. What I ended up with was a quick and dirty WinForms app that allows me to pick a root folder, and then shows all the -MachineName files: I start by picking a base folder and a template to search for - typically the -MachineName. Clicking Go brings up a list of all files in that folder and its subdirectories.  The list also displays the dates for the saved (-MachineName) file and the current file on disk, along with highlighting for the newer of the two. I can right click on any file and get a context menu pop up to open the folder in Explorer, or open Beyond Compare and view the two files to compare differences which I found very helpful for a number of files where I had modified the files after SkyDrive had updated to an old one. Typically these would be the green files (of which there were thankfully few). To 'fix' files I can select any number of files in the list, then use one of the three buttons on the right to apply an operation. I can use the Saved files - that is the backup file that SkyDrive created with the -MachineName extension (-RasXps above). Or I can use the current file, which is the file with the right name on disk right now and delete the -MachineName file. Or on some occasions I can just opt to delete both of them. For some files like binaries it's often easier to just delete and them be rebuild than choosing. For the most part the process involves accepting the pink files, and checking the few green files and see if any modifications were made since the file was updated incorrectly by SkyDrive. For me luckily those are few in number. Anyways, I thought I share this utility in case anybody else runs into this issue. I've included the VS2012 solution and all the source code so you can see how it works and you can tweak it as needed. The .NET 4.5 binaries are also included if you can't compile. Be warned though!  This rough code is provided as is and makes no guarantees or claims about file safety. All three of the action buttons on the form will delete data. It's a very rough utility and there are no safeguards that ask nicely before deleting files. I highly recommend you make a backup before you have at it. This tools is very narrow in focus, but it might also work with other sync issues from other vendors. I seem to remember that I had similar issues with SugarSync at some point and it too created the -MachineName style files on sync conflicts. Hope this helps somebody out so you can avoid wasting the better part of a full work day on this… Resources Download the Source Code and Binaries for SkyDrive Rescue© Rick Strahl, West Wind Technologies, 2005-2013Posted in Windows  .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Dynamic Code for type casting Generic Types 'generically' in C#

  - by Rick Strahl

  C# is a strongly typed language and while that's a fundamental feature of the language there are more and more situations where dynamic types make a lot of sense. I've written quite a bit about how I use dynamic for creating new type extensions: Dynamic Types and DynamicObject References in C# Creating a dynamic, extensible C# Expando Object Creating a dynamic DataReader for dynamic Property Access Today I want to point out an example of a much simpler usage for dynamic that I use occasionally to get around potential static typing issues in C# code especially those concerning generic types. TypeCasting Generics Generic types have been around since .NET 2.0 I've run into a number of situations in the past - especially with generic types that don't implement specific interfaces that can be cast to - where I've been unable to properly cast an object when it's passed to a method or assigned to a property. Granted often this can be a sign of bad design, but in at least some situations the code that needs to be integrated is not under my control so I have to make due with what's available or the parent object is too complex or intermingled to be easily refactored to a new usage scenario. Here's an example that I ran into in my own RazorHosting library - so I have really no excuse, but I also don't see another clean way around it in this case. A Generic Example Imagine I've implemented a generic type like this: public class RazorEngine<TBaseTemplateType> where TBaseTemplateType : RazorTemplateBase, new() You can now happily instantiate new generic versions of this type with custom template bases or even a non-generic version which is implemented like this: public class RazorEngine : RazorEngine<RazorTemplateBase> { public RazorEngine() : base() { } } To instantiate one: var engine = new RazorEngine<MyCustomRazorTemplate>(); Now imagine that the template class receives a reference to the engine when it's instantiated. This code is fired as part of the Engine pipeline when it gets ready to execute the template. It instantiates the template and assigns itself to the template: var template = new TBaseTemplateType() { Engine = this } The problem here is that possibly many variations of RazorEngine<T> can be passed. I can have RazorTemplateBase, RazorFolderHostTemplateBase, CustomRazorTemplateBase etc. as generic parameters and the Engine property has to reflect that somehow. So, how would I cast that? My first inclination was to use an interface on the engine class and then cast to the interface.  Generally that works, but unfortunately here the engine class is generic and has a few members that require the template type in the member signatures. So while I certainly can implement an interface: public interface IRazorEngine<TBaseTemplateType> it doesn't really help for passing this generically templated object to the template class - I still can't cast it if multiple differently typed versions of the generic type could be passed. I have the exact same issue in that I can't specify a 'generic' generic parameter, since there's no underlying base type that's common. In light of this I decided on using object and the following syntax for the property (and the same would be true for a method parameter): public class RazorTemplateBase :MarshalByRefObject,IDisposable { public object Engine {get;set; } } Now because the Engine property is a non-typed object, when I need to do something with this value, I still have no way to cast it explicitly. What I really would need is: public RazorEngine<> Engine { get; set; } but that's not possible. Dynamic to the Rescue Luckily with the dynamic type this sort of thing can be mitigated fairly easily. For example here's a method that uses the Engine property and uses the well known class interface by simply casting the plain object reference to dynamic and then firing away on the properties and methods of the base template class that are common to all templates:/// <summary> /// Allows rendering a dynamic template from a string template /// passing in a model. This is like rendering a partial /// but providing the input as a /// </summary> public virtual string RenderTemplate(string template,object model) { if (template == null) return string.Empty; // if there's no template markup if(!template.Contains("@")) return template; // use dynamic to get around generic type casting dynamic engine = Engine; string result = engine.RenderTemplate(template, model); if (result == null) throw new ApplicationException("RenderTemplate failed: " + engine.ErrorMessage); return result; } Prior to .NET 4.0  I would have had to use Reflection for this sort of thing which would have a been a heck of a lot more verbose, but dynamic makes this so much easier and cleaner and in this case at least the overhead is negliable since it's a single dynamic operation on an otherwise very complex operation call. Dynamic as  a Bailout Sometimes this sort of thing often reeks of a design flaw, and I agree that in hindsight this could have been designed differently. But as is often the case this particular scenario wasn't planned for originally and removing the generic signatures from the base type would break a ton of other code in the framework. Given the existing fairly complex engine design, refactoring an interface to remove generic types just to make this particular code work would have been overkill. Instead dynamic provides a nice and simple and relatively clean solution. Now if there were many other places where this occurs I would probably consider reworking the code to make this cleaner but given this isolated instance and relatively low profile operation use of dynamic seems a valid choice for me. This solution really works anywhere where you might end up with an inheritance structure that doesn't have a common base or interface that is sufficient. In the example above I know what I'm getting but there's no common base type that I can cast to. All that said, it's a good idea to think about use of dynamic before you rush in. In many situations there are alternatives that can still work with static typing. Dynamic definitely has some overhead compared to direct static access of objects, so if possible we should definitely stick to static typing. In the example above the application already uses dynamics extensively for dynamic page page templating and passing models around so introducing dynamics here has very little additional overhead. The operation itself also fires of a fairly resource heavy operation where the overhead of a couple of dynamic member accesses are not a performance issue. So, what's your experience with dynamic as a bailout mechanism? © Rick Strahl, West Wind Technologies, 2005-2012Posted in CSharp   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Process.Start() and ShellExecute() fails with URLs on Windows 8

  - by Rick Strahl

  Since I installed Windows 8 I've noticed that a number of my applications appear to have problems opening URLs. That is when I click on a link inside of a Windows application, either nothing happens or there's an error that occurs. It's happening both to my own applications and a host of Windows applications I'm running. At first I thought this was an issue with my default browser (Chrome) but after switching the default browser to a few others and experimenting a bit I noticed that the errors occur - oddly enough - only when I run an application as an Administrator. I also tried switching to FireFox and Opera as my default browser and saw exactly the same behavior. The scenario for this is a bit bizarre: Running on Windows 8 Call Process.Start() (or ShellExecute() in Win32 API) with a URL or an HTML file Run 'As Administrator' (works fine under non-elevated user account!) or with UAC off A browser other than Internet Explorer is set as your Default Web Browser Talk about a weird scenario: Something that doesn't work when you run as an Administrator which is supposed to have rights to everything on the system! Instead running under an Admin account - either elevated with a User Account Control prompt or even when running as a full Administrator fails. It appears that this problem does not occur for everyone, but when I looked for a solution to this, I saw quite a few posts in relation to this with no clear resolutions. I have three Windows 8 machines running here in the office and all three of them showed this behavior. Lest you think this is just a programmer's problem - this can affect any software running on your system that needs to run under administrative rights. Try it out Now, in order for this next example to fail, any browser but Internet Explorer has to be your default browser and even then it may not fail depending on how you installed your browser. To see if this is a problem create a small Console application and call Process.Start() with a URL in it:namespace Win8ShellBugConsole { class Program { static void Main(string[] args) { Console.WriteLine("Launching Url..."); Process.Start("http://microsoft.com"); Console.Write("Press any key to continue..."); Console.ReadKey(); Console.WriteLine("\r\n\r\nLaunching image..."); Process.Start(Path.GetFullPath(@"..\..\sailbig.jpg")); Console.Write("Press any key to continue..."); Console.ReadKey(); } } } Compile this code. Then execute the code from Explorer (not from Visual Studio because that may change the permissions). If you simply run the EXE and you're not running as an administrator, you'll see the Web page pop up in the browser as well as the image loading. Now run the same thing with Run As Administrator: Now when you run it you get a nice error when Process.Start() is fired: The same happens if you are running with User Account Control off altogether - ie. you are running as a full admin account. Now if you comment out the URL in the code above and just fire the image display - that works just fine in any user mode. As does opening any other local file type or even starting a new EXE locally (ie. Process.Start("c:\windows\notepad.exe"). All that works, EXCEPT for URLs. The code above uses Process.Start() in .NET but the same happens in Win32 Applications that use the ShellExecute API. In some of my older Fox apps ShellExecute returns an error code of 31 - which is No Shell Association found. What's the Deal? It turns out the problem has to do with the way browsers are registering themselves on Windows. Internet Explorer - being a built-in application in Windows 8 - apparently does this correctly, but other browsers possibly don't or at least didn't at the time I installed them. So even Chrome, which continually updates itself, has a recent version that apparently has this registration issue fixed, I was unable to simply set IE as my default browser then use Chrome to 'Set as Default Browser'. It still didn't work. Neither did using the Set Program Associations dialog which lets you assign what extensions are mapped to by a given application. Each application provides a set of extension/moniker mappings that it supports and this dialog lets you associate them on a system wide basis. This also did not work for Chrome or any of the other browsers at first. However, after repeated retries here eventually I did manage to get FireFox to work, but not any of the others. What Works? Reinstall the Browser In the end I decided on the hard core pull the plug solution: Totally uninstall and re-install Chrome in this case. And lo and behold, after reinstall everything was working fine. Now even removing the association for Chrome, switching to IE as the default browser and then back to Chrome works. But, even though the version of Chrome I was running before uninstalling and reinstalling is the same as I'm running now after the reinstall now it works. Of course I had to find out the hard way, before Richard commented with a note regarding what the issue is with Chrome at least: http://code.google.com/p/chromium/issues/detail?id=156400 As expected the issue is a registration issue - with keys not being registered at the machine level. Reading this I'm still not sure why this should be a problem - an elevated account still runs under the same user account (ie. I'm still rickstrahl even if I Run As Administrator), so why shouldn't an app be able to read my Current User registry hive? And also that doesn't quite explain why if I register the extensions using Run As Administrator in Chrome when using Set as Default Browser). But in the end it works… Not so fast It's now a couple of days later and still there are some oddball problems although this time they appear to be purely Chrome issues. After the reinstall Chrome seems to pop up properly with ShellExecute() calls both in regular user and Admin mode. However, it now looks like Chrome is actually running two completely separate user profiles for each. For example, when I run Visual Studio in Admin mode and go to View in browser, Chrome complains that it was installed in Admin mode and can't launch (WTF?). Then you retry a few times later and it ends up working. When launched that way some of the plug-ins installed don't show up with the effect that sometimes they're visible sometimes they're not. Also Chrome seems to loose my configuration and Google sign in between sessions now, presumably when switching user modes. Add-ins installed in admin mode don't show up in user mode and vice versa. Ah, this is lovely. Did I mention that I freaking hate UAC precisely because of this kind of bullshit. You can never tell exactly what account your app is running under, and apparently apps also have a hard time trying to put data into the right place that works for both scenarios. And as my recent post on using Windows Live accounts shows it's yet another level of abstraction ontop of the underlying system identity that can cause all sort of small side effect headaches like this. Hopefully, most of you are skirting this issue altogether - having installed more recent versions of your favorite browsers. If not, hopefully this post will take you straight to reinstallation to fix this annoying issue.© Rick Strahl, West Wind Technologies, 2005-2012Posted in Windows  .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Physical Directories vs. MVC View Paths

  - by Rick Strahl

  This post falls into the bucket of operator error on my part, but I want to share this anyway because it describes an issue that has bitten me a few times now and writing it down might keep it a little stronger in my mind. I've been working on an MVC project the last few days, and at the end of a long day I accidentally moved one of my View folders from the MVC Root Folder to the project root. It must have been at the very end of the day before shutting down because tests and manual site navigation worked fine just before I quit for the night. I checked in changes and called it a night. Next day I came back, started running the app and had a lot of breaks with certain views. Oddly custom routes to these controllers/views worked, but stock /{controller}/{action} routes would not. After a bit of spelunking I realized that "Hey one of my View Folders is missing", which made some sense given the error messages I got. I looked in the recycle bin - nothing there, so rather than try to figure out what the hell happened, just restored from my last SVN checkin. At this point the folders are back… but… view access  still ends up breaking for this set of views. Specifically I'm getting the Yellow Screen of Death with: CS0103: The name 'model' does not exist in the current context Here's the full error: Server Error in '/ClassifiedsWeb' Application. Compilation ErrorDescription: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.Compiler Error Message: CS0103: The name 'model' does not exist in the current contextSource Error: Line 1: @model ClassifiedsWeb.EntryViewModel Line 2: @{ Line 3: ViewBag.Title = Model.Entry.Title + " - " + ClassifiedsBusiness.App.Configuration.ApplicationName; Source File: c:\Projects2010\Clients\GorgeNet\Classifieds\ClassifiedsWeb\Classifieds\Show.cshtml    Line: 1 Compiler Warning Messages: Show Detailed Compiler Output: Show Complete Compilation Source: Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.272 Here's what's really odd about this error: The views now do exist in the /Views/Classifieds folder of the project, but it appears like MVC is trying to execute the views directly. This is getting pretty weird, man! So I hook up some break points in my controllers to see if my controller actions are getting fired - and sure enough it turns out they are not - but only for those views that were previously 'lost' and then restored from SVN. WTF? At this point I'm thinking that I must have messed up one of the config files, but after some more spelunking and realizing that all the other Controller views work, I give up that idea. Config's gotta be OK if other controllers and views are working. Root Folders and MVC Views don't mix As I mentioned the problem was the fact that I inadvertantly managed to drag my View folder to the root folder of the project. Here's what this looks like in my FUBAR'd project structure after I copied back /Views/Classifieds folder from SVN: There's the actual root folder in the /Views folder and the accidental copy that sits of the root. I of course did not notice the /Classifieds folder at the root because it was excluded and didn't show up in the project. Now, before you call me a complete idiot remember that this happened by accident - an accidental drag probably just before shutting down for the night. :-) So why does this break? MVC should be happy with views in the /Views/Classifieds folder right? While MVC might be happy, IIS is not. The fact that there is a physical folder on disk takes precedence over MVC's routing. In other words if a URL exists that matches a route the pysical path is accessed first. What happens here is that essentially IIS is trying to execute the .cshtml pages directly without ever routing to the Controller methods. In the error page I showed above my clue should have been that the view was served as: c:\Projects2010\Clients\GorgeNet\Classifieds\ClassifiedsWeb\Classifieds\Show.cshtml rather than c:\Projects2010\Clients\GorgeNet\Classifieds\ClassifiedsWeb\Views\Classifieds\Show.cshtml But of course I didn't notice that right away, just skimming to the end and looking at the file name. The reason that /classifieds/list actually fires that file is that the ASP.NET Web Pages engine looks for physical files on disk that match a path. IOW, when calling Web Pages you drop the .cshtml off the Razor page and IIS will serve that just fine. So: /classifieds/list looks and tries to find /classifieds/list.cshtml and executes that script. And that is exactly what's happening. Web Pages is trying to execute the .cshtml file and it fails because Web Pages knows nothing about the @model tag which is an MVC specific template extension. This is why my breakpoints in the controller methods didn't fire and it also explains why the error mentions that the @model key word is invalid (@model is an MVC provided template enhancement to the Razor Engine). The solution of course is super simple: Delete the accidentally created root folder and the problem is solved. Routing and Physical Paths I've run into problems with this before actually. In the past I've had a number of applications that had a physical /Admin folder which also would conflict with an MVC Admin controller. More than once I ended up wondering why the index route (/Admin/) was not working properly. If a physical /Admin folder exists /Admin will not route to the Index action (or whatever default action you have set up, but instead try to list the directory or show the default document in the folder. The only way to force the index page through MVC is to explicitly use /Admin/Index. Makes perfect sense once you realize the physical folder is there, but that's easy to forget in an MVC application. As you might imagine after a few times of running into this I gave up on the Admin folder and moved everything into MVC views to handle those operations. Still it's one of those things that can easily bite you, because the behavior and error messages seem to point at completely different  problems. Moral of the story is: If you see routing problems where routes are not reaching obvious controller methods, always check to make sure there's isn't a physical path being mapped by IIS instead. That way you won't feel stupid like I did after trying a million things for about an hour before discovering my sloppy mousing behavior :-)© Rick Strahl, West Wind Technologies, 2005-2012Posted in MVC   IIS7   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• HTML5 Input type=date Formatting Issues

  - by Rick Strahl

  One of the nice features in HTML5 is the abililty to specify a specific input type for HTML text input boxes. There a host of very useful input types available including email, number, date, datetime, month, number, range, search, tel, time, url and week. For a more complete list you can check out the MDN reference. Date input types also support automatic validation which can be useful in some scenarios but maybe can get in the way at other times. One of the more common input types, and one that can most benefit of a custom UI for selection is of course date input. Almost every application could use a decent date representation and HTML5's date input type seems to push into the right direction. It'd be nice if you could just say:<form action="DateTest.html"> <label for="FromDate">Enter a Date:</label> <input type="date" id="FromDate" name="FromDate" value="11/08/2012" class="date" /> <hr /> <input type="submit" id="btnSubmit" name="btnSubmit" value="Save Date" class="smallbutton" /> </form> but if you'd expect to just work, you're likely to be pretty disappointed. Problem #1: Browser Support For starters there's browser support. Out of the major browsers only the latest versions of WebKit and Opera based browsers seem to support date input. Neither FireFox, nor any version of Internet Explorer (including the new touch enabled IE10 in Windows RT) support input type=date. Browser support is an issue, but it would be OK if it wasn't for problem #2. Problem #2: Date Formatting If you look at my date input from before:<input type="date" id="FromDate" name="FromDate" value="11/08/2012" class="date" /> You can see that my date is formatted in local date format (ie. en-us). Now when I run this sadly the form that comes up in Chrome (and also iOS mobile browsers) comes up like this: Chrome isn't recognizing my local date string. Instead it's expecting my date format to be provided in ISO 8601 format which is: 2012-11-08 So if I change the date input field to:<input type="date" id="FromDate" name="FromDate" value="2012-10-08" class="date" /> I correctly get the date field filled in: Also when I pick a date with the DatePicker the date value is also returned is also set to the ISO date format. Yet notice how the date is still formatted to the local date time format (ie. en-US format). So if I pick a new date: and then save, the value field is set back to: 2012-11-15 using the ISO format. The same is true for Opera and iOS browsers and I suspect any other WebKit style browser and their date pickers. So to summarize input type=date: Expects ISO 8601 format dates to display intial values Sets selected date values to ISO 8601 Now what? This would sort of make sense, if all browsers supported input type=date. It'd be easy because you could just format dates appropriately when you set the date value into the control by applying the appropriate culture formatting (ie. .ToString("yyyy-MM-dd") ). .NET is actually smart enough to pick up the date on the other end for modelbinding when ISO 8601 is used. For other environments this might be a bit more tricky. input type=date is clearly the way to go forward. Date controls implemented in HTML are going the way of the dodo, given the intricacies of mobile platforms and scaling for both desktop and mobile. I've been using jQuery UI Datepicker for ages but once going to mobile, that's no longer an option as the control doesn't scale down well for mobile apps (at least not without major re-styling). It also makes a lot of sense for the browser to provide this functionality - creating a consistent date input experience across apps only makes sense, which is why I find it baffling that neither FireFox nor IE 10 deign it necessary to support date input natively. The problem is that a large number of even the latest and greatest browsers don't support this. So now you're stuck with not knowing what date format you have to serve since neither the local format, nor the ISO format works in all cases. For my current app I just broke down and used the ISO format and so I'll live with the non-local date format. <input type="date" id="ToDate" name="ToDate" value="2012-11-08" class="date"/> Here's what this looks like on Chrome: Here's what it looks like on my iPhone: Both Chrome and the phone do this the way it should be. For the phone especially this demonstrates why we'd want this - the built-in date picker there certainly beats manually trying to edit the date using finger gymnastics, and it's one of the easiest ways to pick a date I can think of (ie. easier to use than your typical date picker). Finally here's what the date looks like in FireFox: Certainly this is not the ideal date format, but it's clear enough I suppose. If users enter a date in local US format and that works as well (but won't work for other locales). It'll have to do. Over time one can only hope that other browsers will finally decide to implement this functionality natively to provide a unique experience. Until then, incomplete solutions it is. Related Posts Html 5 Input Types - How useful is this really going to be?© Rick Strahl, West Wind Technologies, 2005-2012Posted in HTML5  HTML   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Modern/Metro Internet Explorer: What were they thinking???

  - by Rick Strahl

  As I installed Windows 8.1 last week I decided that I really should take a closer look at Internet Explorer in the Modern/Metro environment again. Right away I ran into two issues that are real head scratchers to me.Modern Split Windows don't resize Viewport but Zoom OutThis one falls in the "WTF, really?" department: It looks like Modern Internet Explorer's Modern doesn't resize the browser window as every other browser (including IE 11 on the desktop) does, but rather tries to adjust the zoom to the width of the browser. This means that if you use the Modern IE browser and you split the display between IE and another application, IE will be zoomed out, with text becoming much, much smaller, rather than resizing the browser viewport and adjusting the pixel width as you would when a browser window is typically resized.Here's what I'm talking about in a couple of pictures. First here's the full screen Internet Explorer version (this shot is resized down since it's full screen at 1080p, click to see the full image):This brings up the first issue which is: On the desktop who wants to browse a site full screen? Most sites aren't fully optimized for 1080p widescreen experience and frankly most content that wide just looks weird. Even in typical 10" resolutions of 1280 width it's weird to look at things this way. At least this issue can be worked around with @media queries and either constraining the view, or adding additional content to make use of the extra space. Still running a desktop browser full screen is not optimal on a desktop machine - ever.Regardless, this view, while oversized, is what I expect: Everything is rendered in the right ratios, with font-size and the responsive design styling properly respected.But now look what happens when you split the desktop windows and show half desktop and have modern IE (this screen shot is not resized but cropped - this is actual size content as you can see in the cropped Twitter window on the right half of the screen):What's happening here is that IE is zooming out of the content to make it fit into the smaller width, shrinking the content rather than resizing the viewport's pixel width. In effect it looks like the pixel width stays at 1080px and the viewport expands out height-wise in response resulting in some crazy long portrait view.There goes responsive design - out the window literally. If you've built your site using @media queries and fixed viewport sizes, Internet Explorer completely screws you in this split view. On my 1080p monitor, the site shown at a little under half width becomes completely unreadable as the fonts are too small and break up. As you go into split view and you resize the window handle the content of the browser gets smaller and smaller (and effectively longer and longer on the bottom) effectively throwing off any responsive layout to the point of un-readability even on a big display, let alone a small tablet screen.What could POSSIBLY be the benefit of this screwed up behavior? I checked around a bit trying different pages in this shrunk down view. Other than the Microsoft home page, every page I went to was nearly unreadable at a quarter width. The only page I found that worked 'normally' was the Microsoft home page which undoubtedly is optimized just for Internet Explorer specifically.Bottom Address Bar opaquely overlays ContentAnother problematic feature for me is the browser address bar on the bottom. Modern IE shows the status bar opaquely on the bottom, overlaying the content area of the Web Page - until you click on the page. Until you do though, the address bar overlays the bottom content solidly. And not just a little bit but by good sizable chunk.In the application from the screen shot above I have an application toolbar on the bottom and the IE Address bar completely hides that bottom toolbar when the page is first loaded, until the user clicks into the content at which point the address bar shrinks down to a fat border style bar with a … on it. Toolbars on the bottom are pretty common these days, especially for mobile optimized applications, so I'd say this is a common use case. But even if you don't have toolbars on the bottom maybe there's other fixed content on the bottom of the page that is vital to display. While other browsers often also show address bars and then later hide them, these other browsers tend to resize the viewport when the address bar status changes, so the content can respond to the size change. Not so with Modern IE. The address bar overlays content and stays visible until content is clicked. No resize notification or viewport height change is sent to the browser.So basically Internet Explorer is telling me: "Our toolbar is more important than your content!" - AND gives me no chance to re-act to that behavior. The result on this page/application is that the user sees no actionable operations until he or she clicks into the content area, which is terrible from a UI perspective as the user has no idea what options are available on initial load.It's doubly confounding in that IE is running in full screen mode and has an the entire height of the screen at its disposal - there's plenty of real estate available to not require this sort of hiding of content in the first place. Heck, even Windows Phone with its more constrained size doesn't hide content - in fact the address bar on Windows Phone 8 is always visible.What were they thinking?Every time I use anything in the Modern Metro interface in Windows 8/8.1 I get angry.  I can pretty much ignore Metro/Modern for my everyday usage, but unfortunately with Internet Explorer in the modern shell I have to live with, because there will be users using it to access my sites. I think it's inexcusable by Microsoft to build such a crappy shell around the browser that impacts the actual usability of Web content. In both of the cases above I can only scratch my head at what could have possibly motivated anybody designing the UI for the browser to make these screwed up choices, that manipulate the content in a totally unmaintainable way.© Rick Strahl, West Wind Technologies, 2005-2013Posted in Windows  HTML5   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• FAQ: GridView Calculation with JavaScript - Editable Price Field

  - by Vincent Maverick Durano

  Recently I wrote a series of blog posts that demonstrates how to do calculation in GridView using JavaScripts. You can check the series of posts below: FAQ: GridView Calculation with JavaScript FAQ: GridView Calculation with JavaScript - Formatting and Validation FAQ: GridView Calculation with JavaScript - Displaying Quantity Total Recently a user in the forums is asking how to calculate the total quantity, sub-totals and total amout in GridView  when a user enters the price and quantity in the TextBox field. Obviously the series of post  that I wrote will not work in this case because the price field in those examples are Label (read-only) and not TextBox fields. In this post I'm going to demonstrate how to accomplish this using the same method used in my previous examples. Basically I'm just going to modify the GridView declaration and replace the Label price field with a TextBox so that users can type on it. And finally modify the CalculateTotals() javascript function. Here are the code blocks below: <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title></title> <script type="text/javascript"> function CalculateTotals() { var gv = document.getElementById("<%= GridView1.ClientID %>"); var tb = gv.getElementsByTagName("input"); var lb = gv.getElementsByTagName("span"); var sub = 0; var total = 0; var indexQ = 1; var indexP = 0; var price = 0; var qty = 0; var totalQty = 0; var tbCount = tb.length / 2; for (var i = 0; i < tbCount; i++) { if (tb[i].type == "text") { ValidateNumber(tb[i + indexQ]); sub = parseFloat(tb[i + indexP].value) * parseFloat(tb[i + indexQ].value); if (isNaN(sub)) { lb[i].innerHTML = "0.00"; sub = 0; } else { lb[i].innerHTML = FormatToMoney(sub, "$", ",", "."); ; } if (isNaN(tb[i + indexQ].value) || tb[i + indexQ].value == "") { qty = 0; } else { qty = tb[i + indexQ].value; } totalQty += parseInt(qty); total += parseFloat(sub); indexQ++; indexP++; } } lb[lb.length - 2].innerHTML = totalQty; lb[lb.length -1].innerHTML = FormatToMoney(total, "$", ",", "."); } function ValidateNumber(o) { if (o.value.length > 0) { o.value = o.value.replace(/[^\d]+/g, ''); //Allow only whole numbers } } function isThousands(position) { if (Math.floor(position / 3) * 3 == position) return true; return false; }; function FormatToMoney(theNumber, theCurrency, theThousands, theDecimal) { var theDecimalDigits = Math.round((theNumber * 100) - (Math.floor(theNumber) * 100)); theDecimalDigits = "" + (theDecimalDigits + "0").substring(0, 2); theNumber = "" + Math.floor(theNumber); var theOutput = theCurrency; for (x = 0; x < theNumber.length; x++) { theOutput += theNumber.substring(x, x + 1); if (isThousands(theNumber.length - x - 1) && (theNumber.length - x - 1 != 0)) { theOutput += theThousands; }; }; theOutput += theDecimal + theDecimalDigits; return theOutput; } </script> </head> <body> <form id="form1" runat="server"> <asp:gridview ID="GridView1" runat="server" ShowFooter="true" AutoGenerateColumns="false"> <Columns> <asp:BoundField DataField="RowNumber" HeaderText="Row Number" /> <asp:BoundField DataField="Description" HeaderText="Item Description" /> <asp:TemplateField HeaderText="Item Price"> <ItemTemplate> <asp:TextBox ID="TXTPrice" runat="server" onkeyup="CalculateTotals();"></asp:TextBox> </ItemTemplate> <FooterTemplate> <b>Total Qty:</b> </FooterTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Quantity"> <ItemTemplate> <asp:TextBox ID="TXTQty" runat="server" onkeyup="CalculateTotals();"></asp:TextBox> </ItemTemplate> <FooterTemplate> <asp:Label ID="LBLQtyTotal" runat="server" Font-Bold="true" ForeColor="Blue" Text="0" ></asp:Label>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <b>Total Amount:</b> </FooterTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Sub-Total"> <ItemTemplate> <asp:Label ID="LBLSubTotal" runat="server" ForeColor="Green" Text="0.00"></asp:Label> </ItemTemplate> <FooterTemplate> <asp:Label ID="LBLTotal" runat="server" ForeColor="Green" Font-Bold="true" Text="0.00"></asp:Label> </FooterTemplate> </asp:TemplateField> </Columns> </asp:gridview> </form> </body> </html>   That's it! I hope someone find this post useful! Technorati Tags: ASP.NET,GridView,JavaScript

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• Dynamic JSON Parsing in .NET with JsonValue

  - by Rick Strahl

  So System.Json has been around for a while in Silverlight, but it's relatively new for the desktop .NET framework and now moving into the lime-light with the pending release of ASP.NET Web API which is bringing a ton of attention to server side JSON usage. The JsonValue, JsonObject and JsonArray objects are going to be pretty useful for Web API applications as they allow you dynamically create and parse JSON values without explicit .NET types to serialize from or into. But even more so I think JsonValue et al. are going to be very useful when consuming JSON APIs from various services. Yes I know C# is strongly typed, why in the world would you want to use dynamic values? So many times I've needed to retrieve a small morsel of information from a large service JSON response and rather than having to map the entire type structure of what that service returns, JsonValue actually allows me to cherry pick and only work with the values I'm interested in, without having to explicitly create everything up front. With JavaScriptSerializer or DataContractJsonSerializer you always need to have a strong type to de-serialize JSON data into. Wouldn't it be nice if no explicit type was required and you could just parse the JSON directly using a very easy to use object syntax? That's exactly what JsonValue, JsonObject and JsonArray accomplish using a JSON parser and some sweet use of dynamic sauce to make it easy to access in code. Creating JSON on the fly with JsonValue Let's start with creating JSON on the fly. It's super easy to create a dynamic object structure. JsonValue uses the dynamic  keyword extensively to make it intuitive to create object structures and turn them into JSON via dynamic object syntax. Here's an example of creating a music album structure with child songs using JsonValue:[TestMethod] public void JsonValueOutputTest() { // strong type instance var jsonObject = new JsonObject(); // dynamic expando instance you can add properties to dynamic album = jsonObject; album.AlbumName = "Dirty Deeds Done Dirt Cheap"; album.Artist = "AC/DC"; album.YearReleased = 1977; album.Songs = new JsonArray() as dynamic; dynamic song = new JsonObject(); song.SongName = "Dirty Deeds Done Dirt Cheap"; song.SongLength = "4:11"; album.Songs.Add(song); song = new JsonObject(); song.SongName = "Love at First Feel"; song.SongLength = "3:10"; album.Songs.Add(song); Console.WriteLine(album.ToString()); } This produces proper JSON just as you would expect: {"AlbumName":"Dirty Deeds Done Dirt Cheap","Artist":"AC\/DC","YearReleased":1977,"Songs":[{"SongName":"Dirty Deeds Done Dirt Cheap","SongLength":"4:11"},{"SongName":"Love at First Feel","SongLength":"3:10"}]} The important thing about this code is that there's no explicitly type that is used for holding the values to serialize to JSON. I am essentially creating this value structure on the fly by adding properties and then serialize it to JSON. This means this code can be entirely driven at runtime without compile time restraints of structure for the JSON output. Here I use JsonObject() to create a new object and immediately cast it to dynamic. JsonObject() is kind of similar in behavior to ExpandoObject in that it allows you to add properties by simply assigning to them. Internally, JsonValue/JsonObject these values are stored in pseudo collections of key value pairs that are exposed as properties through the DynamicObject functionality in .NET. The syntax gets a little tedious only if you need to create child objects or arrays that have to be explicitly defined first. Other than that the syntax looks like normal object access sytnax. Always remember though these values are dynamic - which means no Intellisense and no compiler type checking. It's up to you to ensure that the values you create are accessed consistently and without typos in your code. Note that you can also access the JsonValue instance directly and get access to the underlying type. This means you can assign properties by string, which can be useful for fully data driven JSON generation from other structures. Below you can see both styles of access next to each other:// strong type instance var jsonObject = new JsonObject(); // you can explicitly add values here jsonObject.Add("Entered", DateTime.Now); // expando style instance you can just 'use' properties dynamic album = jsonObject; album.AlbumName = "Dirty Deeds Done Dirt Cheap"; JsonValue internally stores properties keys and values in collections and you can iterate over them at runtime. You can also manipulate the collections if you need to to get the object structure to look exactly like you want. Again, if you've used ExpandoObject before JsonObject/Value are very similar in the behavior of the structure. Reading JSON strings into JsonValue The JsonValue structure supports importing JSON via the Parse() and Load() methods which can read JSON data from a string or various streams respectively. Essentially JsonValue includes the core JSON parsing to turn a JSON string into a collection of JsonValue objects that can be then referenced using familiar dynamic object syntax. Here's a simple example:[TestMethod] public void JsonValueParsingTest() { var jsonString = @"{""Name"":""Rick"",""Company"":""West Wind"",""Entered"":""2012-03-16T00:03:33.245-10:00""}"; dynamic json = JsonValue.Parse(jsonString); // values require casting string name = json.Name; string company = json.Company; DateTime entered = json.Entered; Assert.AreEqual(name, "Rick"); Assert.AreEqual(company, "West Wind"); } The JSON string represents an object with three properties which is parsed into a JsonValue object and cast to dynamic. Once cast to dynamic I can then go ahead and access the object using familiar object syntax. Note that the actual values - json.Name, json.Company, json.Entered - are actually of type JsonPrimitive and I have to assign them to their appropriate types first before I can do type comparisons. The dynamic properties will automatically cast to the right type expected as long as the compiler can resolve the type of the assignment or usage. The AreEqual() method oesn't as it expects two object instances and comparing json.Company to "West Wind" is comparing two different types (JsonPrimitive to String) which fails. So the intermediary assignment is required to make the test pass. The JSON structure can be much more complex than this simple example. Here's another example of an array of albums serialized to JSON and then parsed through with JsonValue():[TestMethod] public void JsonArrayParsingTest() { var jsonString = @"[ { ""Id"": ""b3ec4e5c"", ""AlbumName"": ""Dirty Deeds Done Dirt Cheap"", ""Artist"": ""AC/DC"", ""YearReleased"": 1977, ""Entered"": ""2012-03-16T00:13:12.2810521-10:00"", ""AlbumImageUrl"": ""http://ecx.images-amazon.com/images/I/61kTaH-uZBL._AA115_.jpg"", ""AmazonUrl"": ""http://www.amazon.com/gp/product/B00008BXJ4/ref=as_li_ss_tl?ie=UTF8&tag=westwindtechn-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B00008BXJ4"", ""Songs"": [ { ""AlbumId"": ""b3ec4e5c"", ""SongName"": ""Dirty Deeds Done Dirt Cheap"", ""SongLength"": ""4:11"" }, { ""AlbumId"": ""b3ec4e5c"", ""SongName"": ""Love at First Feel"", ""SongLength"": ""3:10"" }, { ""AlbumId"": ""b3ec4e5c"", ""SongName"": ""Big Balls"", ""SongLength"": ""2:38"" } ] }, { ""Id"": ""67280fb8"", ""AlbumName"": ""Echoes, Silence, Patience & Grace"", ""Artist"": ""Foo Fighters"", ""YearReleased"": 2007, ""Entered"": ""2012-03-16T00:13:12.2810521-10:00"", ""AlbumImageUrl"": ""http://ecx.images-amazon.com/images/I/41mtlesQPVL._SL500_AA280_.jpg"", ""AmazonUrl"": ""http://www.amazon.com/gp/product/B000UFAURI/ref=as_li_ss_tl?ie=UTF8&tag=westwindtechn-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B000UFAURI"", ""Songs"": [ { ""AlbumId"": ""67280fb8"", ""SongName"": ""The Pretender"", ""SongLength"": ""4:29"" }, { ""AlbumId"": ""67280fb8"", ""SongName"": ""Let it Die"", ""SongLength"": ""4:05"" }, { ""AlbumId"": ""67280fb8"", ""SongName"": ""Erase/Replay"", ""SongLength"": ""4:13"" } ] }, { ""Id"": ""7b919432"", ""AlbumName"": ""End of the Silence"", ""Artist"": ""Henry Rollins Band"", ""YearReleased"": 1992, ""Entered"": ""2012-03-16T00:13:12.2800521-10:00"", ""AlbumImageUrl"": ""http://ecx.images-amazon.com/images/I/51FO3rb1tuL._SL160_AA160_.jpg"", ""AmazonUrl"": ""http://www.amazon.com/End-Silence-Rollins-Band/dp/B0000040OX/ref=sr_1_5?ie=UTF8&qid=1302232195&sr=8-5"", ""Songs"": [ { ""AlbumId"": ""7b919432"", ""SongName"": ""Low Self Opinion"", ""SongLength"": ""5:24"" }, { ""AlbumId"": ""7b919432"", ""SongName"": ""Grip"", ""SongLength"": ""4:51"" } ] } ]"; dynamic albums = JsonValue.Parse(jsonString); foreach (dynamic album in albums) { Console.WriteLine(album.AlbumName + " (" + album.YearReleased.ToString() + ")"); foreach (dynamic song in album.Songs) { Console.WriteLine("\t" + song.SongName ); } } Console.WriteLine(albums[0].AlbumName); Console.WriteLine(albums[0].Songs[1].SongName);}   It's pretty sweet how easy it becomes to parse even complex JSON and then just run through the object using object syntax, yet without an explicit type in the mix. In fact it looks and feels a lot like if you were using JavaScript to parse through this data, doesn't it? And that's the point…© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET  Web Api  JSON   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Mapping UrlEncoded POST Values in ASP.NET Web API

  - by Rick Strahl

  If there's one thing that's a bit unexpected in ASP.NET Web API, it's the limited support for mapping url encoded POST data values to simple parameters of ApiController methods. When I first looked at this I thought I was doing something wrong, because it seems mighty odd that you can bind query string values to parameters by name, but can't bind POST values to parameters in the same way. To demonstrate here's a simple example. If you have a Web API method like this:[HttpGet] public HttpResponseMessage Authenticate(string username, string password) { …} and then hit with a URL like this: http://localhost:88/samples/authenticate?Username=ricks&Password=sekrit it works just fine. The query string values are mapped to the username and password parameters of our API method. But if you now change the method to work with [HttpPost] instead like this:[HttpPost] public HttpResponseMessage Authenticate(string username, string password) { …} and hit it with a POST HTTP Request like this: POST http://localhost:88/samples/authenticate HTTP/1.1 Host: localhost:88 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Content-type: application/x-www-form-urlencoded Content-Length: 30 Username=ricks&Password=sekrit you'll find that while the request works, it doesn't actually receive the two string parameters. The username and password parameters are null and so the method is definitely going to fail. When I mentioned this over Twitter a few days ago I got a lot of responses back of why I'd want to do this in the first place - after all HTML Form submissions are the domain of MVC and not WebAPI which is a valid point. However, the more common use case is using POST Variables with AJAX calls. The following is quite common for passing simple values:$.post(url,{ Username: "Rick", Password: "sekrit" },function(result) {…}); but alas that doesn't work. How ASP.NET Web API handles Content Bodies Web API supports parsing content data in a variety of ways, but it does not deal with multiple posted content values. In effect you can only post a single content value to a Web API Action method. That one parameter can be very complex and you can bind it in a variety of ways, but ultimately you're tied to a single POST content value in your parameter definition. While it's possible to support multiple parameters on a POST/PUT operation, only one parameter can be mapped to the actual content - the rest have to be mapped to route values or the query string. Web API treats the whole request body as one big chunk of data that is sent to a Media Type Formatter that's responsible for de-serializing the content into whatever value the method requires. The restriction comes from async nature of Web API where the request data is read only once inside of the formatter that retrieves and deserializes it. Because it's read once, checking for content (like individual POST variables) first is not possible. However, Web API does provide a couple of ways to access the form POST data: Model Binding - object property mapping to bind POST values FormDataCollection - collection of POST keys/values ModelBinding POST Values - Binding POST data to Object Properties The recommended way to handle POST values in Web API is to use Model Binding, which maps individual urlencoded POST values to properties of a model object provided as the parameter. Model binding requires a single object as input to be bound to the POST data, with each POST key that matches a property name (including nested properties like Address.Street) being mapped and updated including automatic type conversion of simple types. This is a very nice feature - and a familiar one from MVC - that makes it very easy to have model objects mapped directly from inbound data. The obvious drawback with Model Binding is that you need a model for it to work: You have to provide a strongly typed object that can receive the data and this object has to map the inbound data. To rewrite the example above to use ModelBinding I have to create a class maps the properties that I need as parameters:public class LoginData { public string Username { get; set; } public string Password { get; set; } } and then accept the data like this in the API method:[HttpPost] public HttpResponseMessage Authenticate(LoginData login) { string username = login.Username; string password = login.Password; … } This works fine mapping the POST values to the properties of the login object. As a side benefit of this method definition, the method now also allows posting of JSON or XML to the same endpoint. If I change my request to send JSON like this: POST http://localhost:88/samples/authenticate HTTP/1.1 Host: localhost:88 Accept: application/jsonContent-type: application/json Content-Length: 40 {"Username":"ricks","Password":"sekrit"} it works as well and transparently, courtesy of the nice Content Negotiation features of Web API. There's nothing wrong with using Model binding and in fact it's a common practice to use (view) model object for inputs coming back from the client and mapping them into these models. But it can be  kind of a hassle if you have AJAX applications with a ton of backend hits, especially if many methods are very atomic and focused and don't effectively require a model or view. Not always do you have to pass structured data, but sometimes there are just a couple of simple response values that need to be sent back. If all you need is to pass a couple operational parameters, creating a view model object just for parameter purposes seems like overkill. Maybe you can use the query string instead (if that makes sense), but if you can't then you can often end up with a plethora of 'message objects' that serve no further  purpose than to make Model Binding work. Note that you can accept multiple parameters with ModelBinding so the following would still work:[HttpPost] public HttpResponseMessage Authenticate(LoginData login, string loginDomain) but only the object will be bound to POST data. As long as loginDomain comes from the querystring or route data this will work. Collecting POST values with FormDataCollection Another more dynamic approach to handle POST values is to collect POST data into a FormDataCollection. FormDataCollection is a very basic key/value collection (like FormCollection in MVC and Request.Form in ASP.NET in general) and then read the values out individually by querying each. [HttpPost] public HttpResponseMessage Authenticate(FormDataCollection form) { var username = form.Get("Username"); var password = form.Get("Password"); …} The downside to this approach is that it's not strongly typed, you have to handle type conversions on non-string parameters, and it gets a bit more complicated to test such as setup as you have to seed a FormDataCollection with data. On the other hand it's flexible and easy to use and especially with string parameters is easy to deal with. It's also dynamic, so if the client sends you a variety of combinations of values on which you make operating decisions, this is much easier to work with than a strongly typed object that would have to account for all possible values up front. The downside is that the code looks old school and isn't as self-documenting as a parameter list or object parameter would be. Nevertheless it's totally functionality and a viable choice for collecting POST values. What about [FromBody]? Web API also has a [FromBody] attribute that can be assigned to parameters. If you have multiple parameters on a Web API method signature you can use [FromBody] to specify which one will be parsed from the POST content. Unfortunately it's not terribly useful as it only returns content in raw format and requires a totally non-standard format ("=content") to specify your content. For more info in how FromBody works and several related issues to how POST data is mapped, you can check out Mike Stalls post: How WebAPI does Parameter Binding Not really sure where the Web API team thought [FromBody] would really be a good fit other than a down and dirty way to send a full string buffer. Extending Web API to make multiple POST Vars work? Don't think so Clearly there's no native support for multiple POST variables being mapped to parameters, which is a bit of a bummer. I know in my own work on one project my customer actually found this to be a real sticking point in their AJAX backend work, and we ended up not using Web API and using MVC JSON features instead. That's kind of sad because Web API is supposed to be the proper solution for AJAX backends. With all of ASP.NET Web API's extensibility you'd think there would be some way to build this functionality on our own, but after spending a bit of time digging and asking some of the experts from the team and Web API community I didn't hear anything that even suggests that this is possible. From what I could find I'd say it's not possible primarily because Web API's Routing engine does not account for the POST variable mapping. This means [HttpPost] methods with url encoded POST buffers are not mapped to the parameters of the endpoint, and so the routes would never even trigger a request that could be intercepted. Once the routing doesn't work there's not much that can be done. If somebody has an idea how this could be accomplished I would love to hear about it. Do we really need multi-value POST mapping? I think that that POST value mapping is a feature that one would expect of any API tool to have. If you look at common APIs out there like Flicker and Google Maps etc. they all work with POST data. POST data is very prominent much more so than JSON inputs and so supporting as many options that enable would seem to be crucial. All that aside, Web API does provide very nice features with Model Binding that allows you to capture many POST variables easily enough, and logistically this will let you build whatever you need with POST data of all shapes as long as you map objects. But having to have an object for every operation that receives a data input is going to take its toll in heavy AJAX applications, with a lot of types created that do nothing more than act as parameter containers. I also think that POST variable mapping is an expected behavior and Web APIs non-support will likely result in many, many questions like this one: How do I bind a simple POST value in ASP.NET WebAPI RC? with no clear answer to this question. I hope for V.next of WebAPI Microsoft will consider this a feature that's worth adding. Related Articles Passing multiple POST parameters to Web API Controller Methods Mike Stall's post: How Web API does Parameter Binding Where does ASP.NET Web API Fit?© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• ASP.NET MVC Postbacks and HtmlHelper Controls ignoring Model Changes

  - by Rick Strahl

  So here's a binding behavior in ASP.NET MVC that I didn't really get until today: HtmlHelpers controls (like .TextBoxFor() etc.) don't bind to model values on Postback, but rather get their value directly out of the POST buffer from ModelState. Effectively it looks like you can't change the display value of a control via model value updates on a Postback operation. To demonstrate here's an example. I have a small section in a document where I display an editable email address: This is what the form displays on a GET operation and as expected I get the email value displayed in both the textbox and plain value display below, which reflects the value in the mode. I added a plain text value to demonstrate the model value compared to what's rendered in the textbox. The relevant markup is the email address which needs to be manipulated via the model in the Controller code. Here's the Razor markup: <div class="fieldcontainer"> <label> Email: &nbsp; <small>(username and <a href="http://gravatar.com">Gravatar</a> image)</small> </label> <div> @Html.TextBoxFor( mod=> mod.User.Email, new {type="email",@class="inputfield"}) @Model.User.Email </div> </div>   So, I have this form and the user can change their email address. On postback the Post controller code then asks the business layer whether the change is allowed. If it's not I want to reset the email address back to the old value which exists in the database and was previously store. The obvious thing to do would be to modify the model. Here's the Controller logic block that deals with that:// did user change email? if (!string.IsNullOrEmpty(oldEmail) && user.Email != oldEmail) { if (userBus.DoesEmailExist(user.Email)) { userBus.ValidationErrors.Add("New email address exists already. Please…"); user.Email = oldEmail; } else // allow email change but require verification by forcing a login user.IsVerified = false; }… model.user = user; return View(model); The logic is straight forward - if the new email address is not valid because it already exists I don't want to display the new email address the user entered, but rather the old one. To do this I change the value on the model which effectively does this:model.user.Email = oldEmail; return View(model); So when I press the Save button after entering in my new email address ([email protected]) here's what comes back in the rendered view: Notice that the textbox value and the raw displayed model value are different. The TextBox displays the POST value, the raw value displays the actual model value which are different. This means that MVC renders the textbox value from the POST data rather than from the view data when an Http POST is active. Now I don't know about you but this is not the behavior I expected - initially. This behavior effectively means that I cannot modify the contents of the textbox from the Controller code if using HtmlHelpers for binding. Updating the model for display purposes in a POST has in effect - no effect. (Apr. 25, 2012 - edited the post heavily based on comments and more experimentation) What should the behavior be? After getting quite a few comments on this post I quickly realized that the behavior I described above is actually the behavior you'd want in 99% of the binding scenarios. You do want to get the POST values back into your input controls at all times, so that the data displayed on a form for the user matches what they typed. So if an error occurs, the error doesn't mysteriously disappear getting replaced either with a default value or some value that you changed on the model on your own. Makes sense. Still it is a little non-obvious because the way you create the UI elements with MVC, it certainly looks like your are binding to the model value:@Html.TextBoxFor( mod=> mod.User.Email, new {type="email",@class="inputfield",required="required" }) and so unless one understands a little bit about how the model binder works this is easy to trip up. At least it was for me. Even though I'm telling the control which model value to bind to, that model value is only used initially on GET operations. After that ModelState/POST values provide the display value. Workarounds The default behavior should be fine for 99% of binding scenarios. But if you do need fix up values based on your model rather than the default POST values, there are a number of ways that you can work around this. Initially when I ran into this, I couldn't figure out how to set the value using code and so the simplest solution to me was simply to not use the MVC Html Helper for the specific control and explicitly bind the model via HTML markup and @Razor expression: <input type="text" name="User.Email" id="User_Email" value="@Model.User.Email" /> And this produces the right result. This is easy enough to create, but feels a little out of place when using the @Html helpers for everything else. As you can see by the difference in the name and id values, you also are forced to remember the naming conventions that MVC imposes in order for ModelBinding to work properly which is a pain to remember and set manually (name is the same as the property with . syntax, id replaces dots with underlines). Use the ModelState Some of my original confusion came because I didn't understand how the model binder works. The model binder basically maintains ModelState on a postback, which holds a value and binding errors for each of the Post back value submitted on the page that can be mapped to the model. In other words there's one ModelState entry for each bound property of the model. Each ModelState entry contains a value property that holds AttemptedValue and RawValue properties. The AttemptedValue is essentially the POST value retrieved from the form. The RawValue is the value that the model holds. When MVC binds controls like @Html.TextBoxFor() or @Html.TextBox(), it always binds values on a GET operation. On a POST operation however, it'll always used the AttemptedValue to display the control. MVC binds using the ModelState on a POST operation, not the model's value. So, if you want the behavior that I was expecting originally you can actually get it by clearing the ModelState in the controller code:ModelState.Clear(); This clears out all the captured ModelState values, and effectively binds to the model. Note this will produce very similar results - in fact if there are no binding errors you see exactly the same behavior as if binding from ModelState, because the model has been updated from the ModelState already and binding to the updated values most likely produces the same values you would get with POST back values. The big difference though is that any values that couldn't bind - like say putting a string into a numeric field - will now not display back the value the user typed, but the default field value or whatever you changed the model value to. This is the behavior I was actually expecting previously. But - clearing out all values might be a bit heavy handed. You might want to fix up one or two values in a model but rarely would you want the entire model to update from the model. So, you can also clear out individual values on an as needed basis:if (userBus.DoesEmailExist(user.Email)) { userBus.ValidationErrors.Add("New email address exists already. Please…"); user.Email = oldEmail; ModelState.Remove("User.Email"); } This allows you to remove a single value from the ModelState and effectively allows you to replace that value for display from the model. Why? While researching this I came across a post from Microsoft's Brad Wilson who describes the default binding behavior best in a forum post: The reason we use the posted value for editors rather than the model value is that the model may not be able to contain the value that the user typed. Imagine in your "int" editor the user had typed "dog". You want to display an error message which says "dog is not valid", and leave "dog" in the editor field. However, your model is an int: there's no way it can store "dog". So we keep the old value. If you don't want the old values in the editor, clear out the Model State. That's where the old value is stored and pulled from the HTML helpers. There you have it. It's not the most intuitive behavior, but in hindsight this behavior does make some sense even if at first glance it looks like you should be able to update values from the model. The solution of clearing ModelState works and is a reasonable one but you have to know about some of the innards of ModelState and how it actually works to figure that out.© Rick Strahl, West Wind Technologies, 2005-2012Posted in ASP.NET  MVC   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Back to Basics: When does a .NET Assembly Dependency get loaded

  - by Rick Strahl

  When we work on typical day to day applications, it's easy to forget some of the core features of the .NET framework. For me personally it's been a long time since I've learned about some of the underlying CLR system level services even though I rely on them on a daily basis. I often think only about high level application constructs and/or high level framework functionality, but the low level stuff is often just taken for granted. Over the last week at DevConnections I had all sorts of low level discussions with other developers about the inner workings of this or that technology (especially in light of my Low Level ASP.NET Architecture talk and the Razor Hosting talk). One topic that came up a couple of times and ended up a point of confusion even amongst some seasoned developers (including some folks from Microsoft <snicker>) is when assemblies actually load into a .NET process. There are a number of different ways that assemblies are loaded in .NET. When you create a typical project assemblies usually come from: The Assembly reference list of the top level 'executable' project The Assembly references of referenced projects Dynamically loaded at runtime via AppDomain/Reflection loading In addition .NET automatically loads mscorlib (most of the System namespace) the boot process that hosts the .NET runtime in EXE apps, or some other kind of runtime hosting environment (runtime hosting in servers like IIS, SQL Server or COM Interop). In hosting environments the runtime host may also pre-load a bunch of assemblies on its own (for example the ASP.NET host requires all sorts of assemblies just to run itself, before ever routing into your user specific code). Assembly Loading The most obvious source of loaded assemblies is the top level application's assembly reference list. You can add assembly references to a top level application and those assembly references are then available to the application. In a nutshell, referenced assemblies are not immediately loaded - they are loaded on the fly as needed. So regardless of whether you have an assembly reference in a top level project, or a dependent assembly assemblies typically load on an as needed basis, unless explicitly loaded by user code. The same is true of dependent assemblies. To check this out I ran a simple test: I have a utility assembly Westwind.Utilities which is a general purpose library that can work in any type of project. Due to a couple of small requirements for encoding and a logging piece that allows logging Web content (dependency on HttpContext.Current) this utility library has a dependency on System.Web. Now System.Web is a pretty large assembly and generally you'd want to avoid adding it to a non-Web project if it can be helped. So I created a Console Application that loads my utility library: You can see that the top level Console app a reference to Westwind.Utilities and System.Data (beyond the core .NET libs). The Westwind.Utilities project on the other hand has quite a few dependencies including System.Web. I then add a main program that accesses only a simple utillity method in the Westwind.Utilities library that doesn't require any of the classes that access System.Web: static void Main(string[] args) { Console.WriteLine(StringUtils.NewStringId()); Console.ReadLine(); } StringUtils.NewStringId() calls into Westwind.Utilities, but it doesn't rely on System.Web. Any guesses what the assembly list looks like when I stop the code on the ReadLine() command? I'll wait here while you think about it… … … So, when I stop on ReadLine() and then fire up Process Explorer and check the assembly list I get: We can see here that .NET has not actually loaded any of the dependencies of the Westwind.Utilities assembly. Also not loaded is the top level System.Data reference even though it's in the dependent assembly list of the top level project. Since this particular function I called only uses core System functionality (contained in mscorlib) there's in fact nothing else loaded beyond the main application and my Westwind.Utilities assembly that contains the method accessed. None of the dependencies of Westwind.Utilities loaded. If you were to open the assembly in a disassembler like Reflector or ILSpy, you would however see all the compiled in dependencies. The referenced assemblies are in the dependency list and they are loadable, but they are not immediately loaded by the application. In other words the C# compiler and .NET linker are smart enough to figure out the dependencies based on the code that actually is referenced from your application and any dependencies cascading down into the dependencies from your top level application into the referenced assemblies. In the example above the usage requirement is pretty obvious since I'm only calling a single static method and then exiting the app, but in more complex applications these dependency relationships become very complicated - however it's all taken care of by the compiler and linker figuring out what types and members are actually referenced and including only those assemblies that are in fact referenced in your code or required by any of your dependencies. The good news here is: That if you are referencing an assembly that has a dependency on something like System.Web in a few places that are not actually accessed by any of your code or any dependent assembly code that you are calling, that assembly is never loaded into memory! Some Hosting Environments pre-load Assemblies The load behavior can vary however. In Console and desktop applications we have full control over assembly loading so we see the core CLR behavior. However other environments like ASP.NET for example will preload referenced assemblies explicitly as part of the startup process - primarily to minimize load conflicts. Specifically ASP.NET pre-loads all assemblies referenced in the assembly list and the /bin folder. So in Web applications it definitely pays to minimize your top level assemblies if they are not used. Understanding when Assemblies Load To clarify and see it actually happen what I described in the first example , let's look at a couple of other scenarios. To see assemblies loading at runtime in real time lets create a utility function to print out loaded assemblies to the console: public static void PrintAssemblies() { var assemblies = AppDomain.CurrentDomain.GetAssemblies(); foreach (var assembly in assemblies) { Console.WriteLine(assembly.GetName()); } } Now let's look at the first scenario where I have class method that references internally uses System.Web. In the first scenario lets add a method to my main program like this: static void Main(string[] args) { Console.WriteLine(StringUtils.NewStringId()); Console.ReadLine(); PrintAssemblies(); } public static void WebLogEntry() { var entry = new WebLogEntry(); entry.UpdateFromRequest(); Console.WriteLine(entry.QueryString); } UpdateFromWebRequest() internally accesses HttpContext.Current to read some information of the ASP.NET Request object so it clearly needs a reference System.Web to work. In this first example, the method that holds the calling code is never called, but exists as a static method that can potentially be called externally at some point. What do you think will happen here with the assembly loading? Will System.Web load in this example? No - it doesn't. Because the WebLogEntry() method is never called by the mainline application (or anywhere else) System.Web is not loaded. .NET dynamically loads assemblies as code that needs it is called. No code references the WebLogEntry() method and so System.Web is never loaded. Next, let's add the call to this method, which should trigger System.Web to be loaded because a dependency exists. Let's change the code to: static void Main(string[] args) { Console.WriteLine(StringUtils.NewStringId()); Console.WriteLine("--- Before:"); PrintAssemblies(); WebLogEntry(); Console.WriteLine("--- After:"); PrintAssemblies(); Console.ReadLine(); } public static void WebLogEntry() { var entry = new WebLogEntry(); entry.UpdateFromRequest(); Console.WriteLine(entry.QueryString); } Looking at the code now, when do you think System.Web will be loaded? Will the before list include it? Yup System.Web gets loaded, but only after it's actually referenced. In fact, just until before the call to UpdateFromRequest() System.Web is not loaded - it only loads when the method is actually called and requires the reference in the executing code. Moral of the Story So what have we learned - or maybe remembered again? Dependent Assembly References are not pre-loaded when an application starts (by default) Dependent Assemblies that are not referenced by executing code are never loaded Dependent Assemblies are just in time loaded when first referenced in code All of this is nothing new - .NET has always worked like this. But it's good to have a refresher now and then and go through the exercise of seeing it work in action. It's not one of those things we think about everyday, and as I found out last week, I couldn't remember exactly how it worked since it's been so long since I've learned about this. And apparently I'm not the only one as several other people I had discussions with in relation to loaded assemblies also didn't recall exactly what should happen or assumed incorrectly that just having a reference automatically loads the assembly. The moral of the story for me is: Trying at all costs to eliminate an assembly reference from a component is not quite as important as it's often made out to be. For example, the Westwind.Utilities module described above has a logging component, including a Web specific logging entry that supports pulling information from the active HTTP Context. Adding that feature requires a reference to System.Web. Should I worry about this in the scope of this library? Probably not, because if I don't use that one class of nearly a hundred, System.Web never gets pulled into the parent process. IOW, System.Web only loads when I use that specific feature and if I am, well I clearly have to be running in a Web environment anyway to use it realistically. The alternative would be considerably uglier: Pulling out the WebLogEntry class and sticking it into another assembly and breaking up the logging code. In this case - definitely not worth it. So, .NET definitely goes through some pretty nifty optimizations to ensure that it loads only what it needs and in most cases you can just rely on .NET to do the right thing. Sometimes though assembly loading can go wrong (especially when signed and versioned local assemblies are involved), but that's subject for a whole other post…© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET  CSharp   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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