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  • Why the only hidden field that is being filled from GET action is not being passed in model?

    - by user1807954
    Sorry for the long title, I didn't know how to make it any shorter. My code: My model: public class CarFilter { public String carMake { get; set; } public String carModel { get; set; } public String carEdition { get; set; } . . . public String SortBy { get; set; } } public class CarSearch : CarFilter { public List<Car> Car { get; set; } } My controller: public ActionResult SearchResult(CarSearch search) { var cars = from d in db.Cars select d; if (Request.HttpMethod == "POST") { search.SortBy = "Price"; } search.Car = new List<Car>(); search.Car.AddRange(cars); var temp = new List<CarSearch>(); temp.Add(search); return View(temp); } My Index view (where user filters results): @model IEnumerable<Cars.Models.CarSearch> @using (Html.BeginForm("SearchResult", "Home", FormMethod.Post)){..forms and other stuff..} My SearchResult view (where user sees the results of filtration): @model IEnumerable<Cars.Models.CarSearch> @using (Html.BeginForm("SearchResult", "Home", FormMethod.Get)) { @Html.Hidden("carMake") @Html.Hidden("carModel") @Html.Hidden("carEdition") . . . @Html.Hidden("SortBy", temp.SortBy) <input name="SortBy" class="buttons" type="submit" value="Make"/> My goal What I'm trying to do is when user clicked on sort by Make it will have to GET back all the variables in hidden field back to the SearchResult action in order to sort the result (same filtered results). Result Is: <input id="SortBy" name="SortBy" type="hidden" value=""/>. The value is null and it's not being passed but all the other hidden fields such as carMake and etc have value. But when I use foreach it works perfect. Question Why is this like this? the SortBy is in the same model class as other fields in the view. The only difference is that SortBy is not being filled in the Index view with other fields, instead it's being filled in controller action. What is the explanation for this? Am I missing any C# definition or something such as dynamic objects or something?

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  • VSTO is Free But Aspose is Speed

    - by Ken Cox [MVP]
    I’ve taken over the completion, deployment, and maintenance of an ASP.NET Web site that generates Office documents using VSTO. VSTO’s a decent concept and works fine for small-scale scenarios like a desktop app or small intranet. However, with multiple simultaneous requests via ASP.NET, we found the Web server performance suffered badly. To spread out the server’s workload, I implemented MSMQ task queuing via a WCF Windows service.  That helped a lot. IIS didn’t drag with only one VSTO/Office instance running. But I  still found it taking too long to produce a single report. A nicely formatted VSTO Excel document was taking 45 minutes.  (The client  didn’t know any better and therefore considered 45 minutes tolerable.) On my own time, I pulled out an old copy of Aspose.Total for .NET. Within an hour, I had converted the VSTO Excel C# code to Aspose Cells code. The improvement was astonishing: Instead of the 45-minutes, the report took under a minute! I’ve pasted the client’s exact chat response after he tried the speedy Aspose version: “WWWWWOOOOOOOOWWWWWWWW!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!” Microsoft’s VSTO is a free product while the Aspose components cost $$$.  Certainly, it can be a tough call when budgets are tight. If you’re trying to convince the client to shell out for something more suitable for the application, get an eval version of Aspose.Total and offer a direct comparison demo. Ken Full Disclosure: Aspose (like several other component vendors) gives free copies of their suite to MVPs and other .NET influencers.

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  • Tracking changes in Entity Framework 4.0 using POCO Dynamic Proxies across multiple data contexts.

    - by Rob Packwood
    I started messing with EF 4.0 because I am curious about the POCO possibilities... I wanted to simulate disconnected web environment and wrote the following code to simulate this: Save a test object in the database. Retrieve the test object Dispose of the DataContext associated with the test object I used to retrieve it Update the test object Create a new data context and persist the changes on the test object that are automatically tracked within the DynamicProxy generated against my POCO object. The problem is that when I call dataContext.SaveChanges in the Test method above, the updates are not applied. The testStore entity shows a status of "Modified" when I check its EntityStateTracker, but it is no longer modified when I view it within the new dataContext's Stores property. I would have thought that calling the Attach method on the new dataContext would also bring the object's "Modified" state over, but that appears to not be the case. Is there something I am missing? I am definitely working with self-tracking POCOs using DynamicProxies. private static void SaveTestStore(string storeName = "TestStore") { using (var context = new DataContext()) { Store newStore = context.Stores.CreateObject(); newStore.Name = storeName; context.Stores.AddObject(newStore); context.SaveChanges(); } } private static Store GetStore(string storeName = "TestStore") { using (var context = new DataContext()) { return (from store in context.Stores where store.Name == storeName select store).SingleOrDefault(); } } [Test] public void Test_Store_Update_Using_Different_DataContext() { SaveTestStore(); Store testStore = GetStore(); testStore.Name = "Updated"; using (var dataContext = new DataContext()) { dataContext.Stores.Attach(testStore); dataContext.SaveChanges(SaveOptions.DetectChangesBeforeSave); } Store updatedStore = GetStore("Updated"); Assert.IsNotNull(updatedStore); }

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  • Send mail in asp.net

    - by Zerotoinfinite
    Hi Experts, I am using asp.net 3.5 and C#. I want to send mail from asp.net, for that I have got some details from my hosting provider which are these: mail.MySite.net UserName Password But I am unable to send mail through these details, I have done the following changes in my web.config file: <system.net> <mailSettings> <smtp> <network host="mail.MySite.net" port="8080" userName="UserName" password="Password" /> </smtp> </mailSettings> </system.net> Also, at the code behind I am writing this function: MailMessage mail = new MailMessage("webmaster@mySite.net", "[email protected]"); mail.Subject = "Hi"; mail.Body = "Test Mail from ASP.NET"; mail.IsBodyHtml = false; SmtpClient smp = new SmtpClient(); smp.Send(mail); but I am getting error message as message sending failed. Please let me know what I am doing wrong and what I have to do to make it work fine. Thanks in advance.

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  • How do I add ROW_NUMBER to a LINQ query or Entity?

    - by Whozumommy
    I'm stumped by this easy data problem. I'm using the Entity framework and have a database of products. My results page returns a paginated list of these products. Right now my results are ordered by the number of sales of each product, so my code looks like this: return Products.OrderByDescending(u => u.Sales.Count()); This returns an IQueryable dataset of my entities, sorted by the number of sales. I want my results page to show the rank of each product (in the dataset). My results should look like this: Page #1 1. Bananas 2. Apples 3. Coffee Page #2 4. Cookies 5. Ice Cream 6. Lettuce I'm expecting that I just want to add a column in my results using the SQL ROW_NUMBER variable...but I don't know how to add this column to my results datatable. My resulting page does contain a foreach loop, but since I'm using a paginated set I'm guessing using that number to fake a ranking number would NOT be the best approach. So my question is, how do I add a ROW_NUMBER column to my query results in this case?

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  • ASP.NET MVC: How do I validate a model wrapped in a ViewModel?

    - by Deniz Dogan
    For the login page of my website I would like to list the latest news for my site and also display a few fields to let the user log in. So I figured I should make a login view model - I call this LoginVM. LoginVM contains a Login model for the login fields and a List<NewsItem> for the news listing. This is the Login model: public class Login { [Required(ErrorMessage="Enter a username.")] [DisplayName("Username")] public string Username { get; set; } [Required(ErrorMessage="Enter a password.")] [DataType(DataType.Password)] [DisplayName("Password")] public string Password { get; set; } } This is the LoginVM view model: public class LoginVM { public Login login { get; set; } public List<NewsItem> newsItems { get; set; } } This is where I get stuck. In my login controller, I get passed a LoginVM. [HttpPost] public ActionResult Login(LoginVM model, FormCollection form) { if (ModelState.IsValid) { // What? In the code I'm checking whether ModelState is valid and this would work fine if the view model was actually the Login model, but now it's LoginVM which has no validation attributes at all. How do I make LoginVM "traverse" through its members to validate them all? Am I doing something fundamentally wrong using ModelState in this manner?

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  • Accessing both stored procedure output parameters AND the result set in Entity Framework?

    - by MS.
    Is there any way of accessing both a result set and output parameters from a stored procedure added in as a function import in an Entity Framework model? I am finding that if I set the return type to "None" such that the designer generated code ends up calling base.ExecuteFunction(...) that I can access the output parameters fine after calling the function (but of course not the result set). Conversely if I set the return type in the designer to a collection of complex types then the designer generated code calls base.ExecuteFunction<T>(...) and the result set is returned as ObjectResult<T> but then the value property for the ObjectParameter instances is NULL rather than containing the proper value that I can see being passed back in Profiler. I speculate the second method is perhaps calling a DataReader and not closing it. Is this a known issue? Any work arounds or alternative approaches? Edit My code currently looks like public IEnumerable<FooBar> GetFooBars( int? param1, string param2, DateTime from, DateTime to, out DateTime? createdDate, out DateTime? deletedDate) { var createdDateParam = new ObjectParameter("CreatedDate", typeof(DateTime)); var deletedDateParam = new ObjectParameter("DeletedDate", typeof(DateTime)); var fooBars = MyContext.GetFooBars(param1, param2, from, to, createdDateParam, deletedDateParam); createdDate = (DateTime?)(createdDateParam.Value == DBNull.Value ? null : createdDateParam.Value); deletedDate = (DateTime?)(deletedDateParam.Value == DBNull.Value ? null : deletedDateParam.Value); return fooBars; }

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  • Microsoft Introduces WebMatrix

    - by Rick Strahl
    originally published in CoDe Magazine Editorial Microsoft recently released the first CTP of a new development environment called WebMatrix, which along with some of its supporting technologies are squarely aimed at making the Microsoft Web Platform more approachable for first-time developers and hobbyists. But in the process, it also provides some updated technologies that can make life easier for existing .NET developers. Let’s face it: ASP.NET development isn’t exactly trivial unless you already have a fair bit of familiarity with sophisticated development practices. Stick a non-developer in front of Visual Studio .NET or even the Visual Web Developer Express edition and it’s not likely that the person in front of the screen will be very productive or feel inspired. Yet other technologies like PHP and even classic ASP did provide the ability for non-developers and hobbyists to become reasonably proficient in creating basic web content quickly and efficiently. WebMatrix appears to be Microsoft’s attempt to bring back some of that simplicity with a number of technologies and tools. The key is to provide a friendly and fully self-contained development environment that provides all the tools needed to build an application in one place, as well as tools that allow publishing of content and databases easily to the web server. WebMatrix is made up of several components and technologies: IIS Developer Express IIS Developer Express is a new, self-contained development web server that is fully compatible with IIS 7.5 and based on the same codebase that IIS 7.5 uses. This new development server replaces the much less compatible Cassini web server that’s been used in Visual Studio and the Express editions. IIS Express addresses a few shortcomings of the Cassini server such as the inability to serve custom ISAPI extensions (i.e., things like PHP or ASP classic for example), as well as not supporting advanced authentication. IIS Developer Express provides most of the IIS 7.5 feature set providing much better compatibility between development and live deployment scenarios. SQL Server Compact 4.0 Database access is a key component for most web-driven applications, but on the Microsoft stack this has mostly meant you have to use SQL Server or SQL Server Express. SQL Server Compact is not new-it’s been around for a few years, but it’s been severely hobbled in the past by terrible tool support and the inability to support more than a single connection in Microsoft’s attempt to avoid losing SQL Server licensing. The new release of SQL Server Compact 4.0 supports multiple connections and you can run it in ASP.NET web applications simply by installing an assembly into the bin folder of the web application. In effect, you don’t have to install a special system configuration to run SQL Compact as it is a drop-in database engine: Copy the small assembly into your BIN folder (or from the GAC if installed fully), create a connection string against a local file-based database file, and then start firing SQL requests. Additionally WebMatrix includes nice tools to edit the database tables and files, along with tools to easily upsize (and hopefully downsize in the future) to full SQL Server. This is a big win, pending compatibility and performance limits. In my simple testing the data engine performed well enough for small data sets. This is not only useful for web applications, but also for desktop applications for which a fully installed SQL engine like SQL Server would be overkill. Having a local data store in those applications that can potentially be accessed by multiple users is a welcome feature. ASP.NET Razor View Engine What? Yet another native ASP.NET view engine? We already have Web Forms and various different flavors of using that view engine with Web Forms and MVC. Do we really need another? Microsoft thinks so, and Razor is an implementation of a lightweight, script-only view engine. Unlike the Web Forms view engine, Razor works only with inline code, snippets, and markup; therefore, it is more in line with current thinking of what a view engine should represent. There’s no support for a “page model” or any of the other Web Forms features of the full-page framework, but just a lightweight scripting engine that works with plain markup plus embedded expressions and code. The markup syntax for Razor is geared for minimal typing, plus some progressive detection of where a script block/expression starts and ends. This results in a much leaner syntax than the typical ASP.NET Web Forms alligator (<% %>) tags. Razor uses the @ sign plus standard C# (or Visual Basic) block syntax to delineate code snippets and expressions. Here’s a very simple example of what Razor markup looks like along with some comment annotations: <!DOCTYPE html> <html>     <head>         <title></title>     </head>     <body>     <h1>Razor Test</h1>          <!-- simple expressions -->     @DateTime.Now     <hr />     <!-- method expressions -->     @DateTime.Now.ToString("T")          <!-- code blocks -->     @{         List<string> names = new List<string>();         names.Add("Rick");         names.Add("Markus");         names.Add("Claudio");         names.Add("Kevin");     }          <!-- structured block statements -->     <ul>     @foreach(string name in names){             <li>@name</li>     }     </ul>           <!-- Conditional code -->        @if(true) {                        <!-- Literal Text embedding in code -->        <text>         true        </text>;    }    else    {        <!-- Literal Text embedding in code -->       <text>       false       </text>;    }    </body> </html> Like the Web Forms view engine, Razor parses pages into code, and then executes that run-time compiled code. Effectively a “page” becomes a code file with markup becoming literal text written into the Response stream, code snippets becoming raw code, and expressions being written out with Response.Write(). The code generated from Razor doesn’t look much different from similar Web Forms code that only uses script tags; so although the syntax may look different, the operational model is fairly similar to the Web Forms engine minus the overhead of the large Page object model. However, there are differences: -Razor pages are based on a new base class, Microsoft.WebPages.WebPage, which is hosted in the Microsoft.WebPages assembly that houses all the Razor engine parsing and processing logic. Browsing through the assembly (in the generated ASP.NET Temporary Files folder or GAC) will give you a good idea of the functionality that Razor provides. If you look closely, a lot of the feature set matches ASP.NET MVC’s view implementation as well as many of the helper classes found in MVC. It’s not hard to guess the motivation for this sort of view engine: For beginning developers the simple markup syntax is easier to work with, although you obviously still need to have some understanding of the .NET Framework in order to create dynamic content. The syntax is easier to read and grok and much shorter to type than ASP.NET alligator tags (<% %>) and also easier to understand aesthetically what’s happening in the markup code. Razor also is a better fit for Microsoft’s vision of ASP.NET MVC: It’s a new view engine without the baggage of Web Forms attached to it. The engine is more lightweight since it doesn’t carry all the features and object model of Web Forms with it and it can be instantiated directly outside of the HTTP environment, which has been rather tricky to do for the Web Forms view engine. Having a standalone script parser is a huge win for other applications as well – it makes it much easier to create script or meta driven output generators for many types of applications from code/screen generators, to simple form letters to data merging applications with user customizability. For me personally this is very useful side effect and who knows maybe Microsoft will actually standardize they’re scripting engines (die T4 die!) on this engine. Razor also better fits the “view-based” approach where the view is supposed to be mostly a visual representation that doesn’t hold much, if any, code. While you can still use code, the code you do write has to be self-contained. Overall I wouldn’t be surprised if Razor will become the new standard view engine for MVC in the future – and in fact there have been announcements recently that Razor will become the default script engine in ASP.NET MVC 3.0. Razor can also be used in existing Web Forms and MVC applications, although that’s not working currently unless you manually configure the script mappings and add the appropriate assemblies. It’s possible to do it, but it’s probably better to wait until Microsoft releases official support for Razor scripts in Visual Studio. Once that happens, you can simply drop .cshtml and .vbhtml pages into an existing ASP.NET project and they will work side by side with classic ASP.NET pages. WebMatrix Development Environment To tie all of these three technologies together, Microsoft is shipping WebMatrix with an integrated development environment. An integrated gallery manager makes it easy to download and load existing projects, and then extend them with custom functionality. It seems to be a prominent goal to provide community-oriented content that can act as a starting point, be it via a custom templates or a complete standard application. The IDE includes a project manager that works with a single project and provides an integrated IDE/editor for editing the .cshtml and .vbhtml pages. A run button allows you to quickly run pages in the project manager in a variety of browsers. There’s no debugging support for code at this time. Note that Razor pages don’t require explicit compilation, so making a change, saving, and then refreshing your page in the browser is all that’s needed to see changes while testing an application locally. It’s essentially using the auto-compiling Web Project that was introduced with .NET 2.0. All code is compiled during run time into dynamically created assemblies in the ASP.NET temp folder. WebMatrix also has PHP Editing support with syntax highlighting. You can load various PHP-based applications from the WebMatrix Web Gallery directly into the IDE. Most of the Web Gallery applications are ready to install and run without further configuration, with Wizards taking you through installation of tools, dependencies, and configuration of the database as needed. WebMatrix leverages the Web Platform installer to pull the pieces down from websites in a tight integration of tools that worked nicely for the four or five applications I tried this out on. Click a couple of check boxes and fill in a few simple configuration options and you end up with a running application that’s ready to be customized. Nice! You can easily deploy completed applications via WebDeploy (to an IIS server) or FTP directly from within the development environment. The deploy tool also can handle automatically uploading and installing the database and all related assemblies required, making deployment a simple one-click install step. Simplified Database Access The IDE contains a database editor that can edit SQL Compact and SQL Server databases. There is also a Database helper class that facilitates database access by providing easy-to-use, high-level query execution and iteration methods: @{       var db = Database.OpenFile("FirstApp.sdf");     string sql = "select * from customers where Id > @0"; } <ul> @foreach(var row in db.Query(sql,1)){         <li>@row.FirstName @row.LastName</li> } </ul> The query function takes a SQL statement plus any number of positional (@0,@1 etc.) SQL parameters by simple values. The result is returned as a collection of rows which in turn have a row object with dynamic properties for each of the columns giving easy (though untyped) access to each of the fields. Likewise Execute and ExecuteNonQuery allow execution of more complex queries using similar parameter passing schemes. Note these queries use string-based queries rather than LINQ or Entity Framework’s strongly typed LINQ queries. While this may seem like a step back, it’s also in line with the expectations of non .NET script developers who are quite used to writing and using SQL strings in code rather than using OR/M frameworks. The only question is why was something not included from the beginning in .NET and Microsoft made developers build custom implementations of these basic building blocks. The implementation looks a lot like a DataTable-style data access mechanism, but to be fair, this is a common approach in scripting languages. This type of syntax that uses simple, static, data object methods to perform simple data tasks with one line of code are common in scripting languages and are a good match for folks working in PHP/Python, etc. Seems like Microsoft has taken great advantage of .NET 4.0’s dynamic typing to provide this sort of interface for row iteration where each row has properties for each field. FWIW, all the examples demonstrate using local SQL Compact files - I was unable to get a SQL Server connection string to work with the Database class (the connection string wasn’t accepted). However, since the code in the page is still plain old .NET, you can easily use standard ADO.NET code or even LINQ or Entity Framework models that are created outside of WebMatrix in separate assemblies as required. The good the bad the obnoxious - It’s still .NET The beauty (or curse depending on how you look at it :)) of Razor and the compilation model is that, behind it all, it’s still .NET. Although the syntax may look foreign, it’s still all .NET behind the scenes. You can easily access existing tools, helpers, and utilities simply by adding them to the project as references or to the bin folder. Razor automatically recognizes any assembly reference from assemblies in the bin folder. In the default configuration, Microsoft provides a host of helper functions in a Microsoft.WebPages assembly (check it out in the ASP.NET temp folder for your application), which includes a host of HTML Helpers. If you’ve used ASP.NET MVC before, a lot of the helpers should look familiar. Documentation at the moment is sketchy-there’s a very rough API reference you can check out here: http://www.asp.net/webmatrix/tutorials/asp-net-web-pages-api-reference Who needs WebMatrix? Uhm… good Question Clearly Microsoft is trying hard to create an environment with WebMatrix that is easy to use for newbie developers. The goal seems to be simplicity in providing a minimal development environment and an easy-to-use script engine/language that makes it easy to get started with. There’s also some focus on community features that can be used as starting points, such as Web Gallery applications and templates. The community features in particular are very nice and something that would be nice to eventually see in Visual Studio as well. The question is whether this is too little too late. Developers who have been clamoring for a simpler development environment on the .NET stack have mostly left for other simpler platforms like PHP or Python which are catering to the down and dirty developer. Microsoft will be hard pressed to win those folks-and other hardcore PHP developers-back. Regardless of how much you dress up a script engine fronted by the .NET Framework, it’s still the .NET Framework and all the complexity that drives it. While .NET is a fine solution in its breadth and features once you get a basic handle on the core features, the bar of entry to being productive with the .NET Framework is still pretty high. The MVC style helpers Microsoft provides are a good step in the right direction, but I suspect it’s not enough to shield new developers from having to delve much deeper into the Framework to get even basic applications built. Razor and its helpers is trying to make .NET more accessible but the reality is that in order to do useful stuff that goes beyond the handful of simple helpers you still are going to have to write some C# or VB or other .NET code. If the target is a hobby/amateur/non-programmer the learning curve isn’t made any easier by WebMatrix it’s just been shifted a tad bit further along in your development endeavor when you run out of canned components that are supplied either by Microsoft or the community. The database helpers are interesting and actually I’ve heard a lot of discussion from various developers who’ve been resisting .NET for a really long time perking up at the prospect of easier data access in .NET than the ridiculous amount of code it takes to do even simple data access with raw ADO.NET. It seems sad that such a simple concept and implementation should trigger this sort of response (especially since it’s practically trivial to create helpers like these or pick them up from countless libraries available), but there it is. It also shows that there are plenty of developers out there who are more interested in ‘getting stuff done’ easily than necessarily following the latest and greatest practices which are overkill for many development scenarios. Sometimes it seems that all of .NET is focused on the big life changing issues of development, rather than the bread and butter scenarios that many developers are interested in to get their work accomplished. And that in the end may be WebMatrix’s main raison d'être: To bring some focus back at Microsoft that simpler and more high level solutions are actually needed to appeal to the non-high end developers as well as providing the necessary tools for the high end developers who want to follow the latest and greatest trends. The current version of WebMatrix hits many sweet spots, but it also feels like it has a long way to go before it really can be a tool that a beginning developer or an accomplished developer can feel comfortable with. Although there are some really good ideas in the environment (like the gallery for downloading apps and components) which would be a great addition for Visual Studio as well, the rest of the development environment just feels like crippleware with required functionality missing especially debugging and Intellisense, but also general editor support. It’s not clear whether these are because the product is still in an early alpha release or whether it’s simply designed that way to be a really limited development environment. While simple can be good, nobody wants to feel left out when it comes to necessary tool support and WebMatrix just has that left out feeling to it. If anything WebMatrix’s technology pieces (which are really independent of the WebMatrix product) are what are interesting to developers in general. The compact IIS implementation is a nice improvement for development scenarios and SQL Compact 4.0 seems to address a lot of concerns that people have had and have complained about for some time with previous SQL Compact implementations. By far the most interesting and useful technology though seems to be the Razor view engine for its light weight implementation and it’s decoupling from the ASP.NET/HTTP pipeline to provide a standalone scripting/view engine that is pluggable. The first winner of this is going to be ASP.NET MVC which can now have a cleaner view model that isn’t inconsistent due to the baggage of non-implemented WebForms features that don’t work in MVC. But I expect that Razor will end up in many other applications as a scripting and code generation engine eventually. Visual Studio integration for Razor is currently missing, but is promised for a later release. The ASP.NET MVC team has already mentioned that Razor will eventually become the default MVC view engine, which will guarantee continued growth and development of this tool along those lines. And the Razor engine and support tools actually inherit many of the features that MVC pioneered, so there’s some synergy flowing both ways between Razor and MVC. As an existing ASP.NET developer who’s already familiar with Visual Studio and ASP.NET development, the WebMatrix IDE doesn’t give you anything that you want. The tools provided are minimal and provide nothing that you can’t get in Visual Studio today, except the minimal Razor syntax highlighting, so there’s little need to take a step back. With Visual Studio integration coming later there’s little reason to look at WebMatrix for tooling. It’s good to see that Microsoft is giving some thought about the ease of use of .NET as a platform For so many years, we’ve been piling on more and more new features without trying to take a step back and see how complicated the development/configuration/deployment process has become. Sometimes it’s good to take a step - or several steps - back and take another look and realize just how far we’ve come. WebMatrix is one of those reminders and one that likely will result in some positive changes on the platform as a whole. © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET   IIS7  

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  • C# 5 Async, Part 2: Asynchrony Today

    - by Reed
    The .NET Framework has always supported asynchronous operations.  However, different mechanisms for supporting exist throughout the framework.  While there are at least three separate asynchronous patterns used through the framework, only the latest is directly usable with the new Visual Studio Async CTP.  Before delving into details on the new features, I will talk about existing asynchronous code, and demonstrate how to adapt it for use with the new pattern. The first asynchronous pattern used in the .NET framework was the Asynchronous Programming Model (APM).  This pattern was based around callbacks.  A method is used to start the operation.  It typically is named as BeginSomeOperation.  This method is passed a callback defined as an AsyncCallback, and returns an object that implements IAsyncResult.  Later, the IAsyncResult is used in a call to a method named EndSomeOperation, which blocks until completion and returns the value normally directly returned from the synchronous version of the operation.  Often, the EndSomeOperation call would be called from the callback function passed, which allows you to write code that never blocks. While this pattern works perfectly to prevent blocking, it can make quite confusing code, and be difficult to implement.  For example, the sample code provided for FileStream’s BeginRead/EndRead methods is not simple to understand.  In addition, implementing your own asynchronous methods requires creating an entire class just to implement the IAsyncResult. Given the complexity of the APM, other options have been introduced in later versions of the framework.  The next major pattern introduced was the Event-based Asynchronous Pattern (EAP).  This provides a simpler pattern for asynchronous operations.  It works by providing a method typically named SomeOperationAsync, which signals its completion via an event typically named SomeOperationCompleted. The EAP provides a simpler model for asynchronous programming.  It is much easier to understand and use, and far simpler to implement.  Instead of requiring a custom class and callbacks, the standard event mechanism in C# is used directly.  For example, the WebClient class uses this extensively.  A method is used, such as DownloadDataAsync, and the results are returned via the DownloadDataCompleted event. While the EAP is far simpler to understand and use than the APM, it is still not ideal.  By separating your code into method calls and event handlers, the logic of your program gets more complex.  It also typically loses the ability to block until the result is received, which is often useful.  Blocking often requires writing the code to block by hand, which is error prone and adds complexity. As a result, .NET 4 introduced a third major pattern for asynchronous programming.  The Task<T> class introduced a new, simpler concept for asynchrony.  Task and Task<T> effectively represent an operation that will complete at some point in the future.  This is a perfect model for thinking about asynchronous code, and is the preferred model for all new code going forward.  Task and Task<T> provide all of the advantages of both the APM and the EAP models – you have the ability to block on results (via Task.Wait() or Task<T>.Result), and you can stay completely asynchronous via the use of Task Continuations.  In addition, the Task class provides a new model for task composition and error and cancelation handling.  This is a far superior option to the previous asynchronous patterns. The Visual Studio Async CTP extends the Task based asynchronous model, allowing it to be used in a much simpler manner.  However, it requires the use of Task and Task<T> for all operations.

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  • UPOS RFIDScanner data format

    - by Robert Snyder
    A lot of work that I do currently is based in the OPOS/UPOS world. My company has a device that can read 13.56Mhz tags (RFID), Smart Cards, and Mag Stripe cards. Up until somewhat recently I have only been working with RFID for a very specific scenario. That was to read UltraLight C and Desfire cards. These cards were all setup very specifically so that I could take the data read from those cards and force it into a MSR track2 format. The past couple of weeks, however, I have been working on reading RFID credit cards (since I have a Visa card I've been using mine), and Smart Card credit cards. (The visa card I have has both) In learning how to communicate with SmartCard and reading ISO7816 and EMVCO documents I became a little more familiar with how info is stored. But now I have a question regarding UPOS. The RFID data on my Visa is stored (and read) very similar to how the data is stored and read from the Smart Card on my Visa. Cool. Well in the UPOS spec for SmartCardRW the ReadData method returns a byte array. That's cool, I can just return all that data and then parse it as my heart desires. The RFID though has a LinkedList of Tags. Well this makes sense in terms of my Visa card (reminds me of a question I have in regards to SmartCard, but that is for another question) but what about ULC and Desfire, or for that matter any Mifare card. Pages, Files, Purses don't exactly fit the Tag profile. For instance lets just say I read pages 4-12 on my ULC card. Each page I read is 4 bytes long. Does this mean I have 9 tags in my LinkedList? Is my Tag id the page number? Or then how does that translate to Desfire? I open application 123456 and read file 1 and file 2, Do I have 2 tags? and if so what is my tag id? At least with my Visa I think that I have to use the Tag id (ex 5F24 for my expiration date) and value of {0x15, 0x10, 0x31} Part of me says yes..that makes sense. Another part of me says, "well if that is the case then why doesn't SmartCardRW have Tags?" So that is my question. How do I format my data from those different types of media? or is that the job of my Control Object (the application)? Is so how does it know? The only protocols I have are: // Summary: // Enumerates the available predefined RFID tag protocols the device supports. [Flags] public enum RFIDProtocols { EpcClass0 = 1, RFIDSdt0Plus = 2, EpcClass1 = 4, EpcClass1Gen2 = 8, EpcClass2 = 16, Iso14443A = 4096, Iso14443B = 8192, Iso15693 = 12288, Iso180006B = 16384, Other = 16777216, All = 1073741824, } If I use that well all of my cards that I have are all Iso14443A. I use the ATQA and the SAK to know what type of card I really have. There is no RFID property that lets me specify that. So I'm lost.

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  • Entity Framework - adding new items via a navigation property

    - by Robert
    I have come across what appears to be very peculiar behaviour using entity framework 4.0. I have a User entity, which has a Company (A Company has many Users). If I do this, everything works as expected and I get a nice shiny new user in the database: var company = _model.Companies.First(); company.Users.Add(new User(1, "John", "Smith")); _model.SaveChanges(); However, if I do this, then I get nothing new in the database, and no exceptions thrown: var existingUser = _model.Users.First(); var company = existingUser.Company; company.Users.Add(new User(1, "John", "Smith")); _model.SaveChanges(); So it appears that if I add a User to the Company that is pulled directly from the model, then everything works fine. However if the User is added to a Company that is pulled as a navigation property of another object, then it doesn't work. Can someone tell me if this is expected behaviour, or if there is something I can do to make it so that it is? Thanks!

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  • Entity Framework with MySQL - Timeout Expired while Generating Model

    - by Nathan Taylor
    I've constructed a database in MySQL and I am attempting to map it out with Entity Framework, but I start running into "GenerateSSDLException"s whenever I try to add more than about 20 tables to the EF context. An exception of type 'Microsoft.Data.Entity.Design.VisualStudio.ModelWizard.Engine.ModelBuilderEngine+GenerateSSDLException' occurred while attempting to update from the database. The exception message is: 'An error occurred while executing the command definition. See the inner exception for details.' Fatal error encountered during command execution. Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. There's nothing special about the affected tables, and it's never the same table(s), it's just that after a certain (unspecific) number of tables have been added, the context can no longer be updated without the "Timeout expired" error. Sometimes it's only one table left over, and sometimes it's three; results are pretty unpredictable. Furthermore, the variance in the number of tables which can be added before the error indicates to me that perhaps the problem lies in the size of the query being generated to update the context which includes both the existing table definitions, and also the new tables that are being added to it. Essentially, the SQL query is getting too large and it's failing to execute for some reason. If I generate the model with EdmGen2 it works without any errors, but the generated EDMX file cannot be updated within Visual Studio without producing the aforementioned exception. In all likelihood the source of this problem lies in the tool within Visual Studio given that EdmGen2 works fine, but I'm hoping that perhaps others could offer some advice on how to approach this very unique issue, because it seems like I'm not the only person experiencing it. One suggestion a colleague offered was maintaining two separate EBMX files with some table crossover, but that seems like a pretty ugly fix in my opinion. I suppose this is what I get for trying to use "new technology". :(

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  • Delphi Prism and LINQ to SQL / Entity Framework

    - by Vegar
    I have found many posts and examples of using LINQ-syntax in Delphi Prism (Oxygene), but I have never found anything on LINQ to SQL or Entity Framework. Is it possible to use LINQ to SQL or Entity Framework together with Prism? Where can I found such an example? Update: Olaf is giving an answer through his blog The question is now if any visual tools and code generation is provided, or if everything must be done by hand... Second update: Olaf has answered the tool/code generation-question in a comment on his site: The class designer is there, but there is no Pascal code gen. According to marc hoffman that is currently not on their list. For now you have to live with manual mapping. I guess, if you had Visual Studio (not just the VS shell), that you could add a C# library project to your solution, reference that from your Prism project. Then create the Table-Class mapping in the C# project using the visual designer. Maybe somewhat ugly, but possibly the key to get the Designer + CodeGen integrated into Prism. Who cares what language is used for the mapping . I will say this is a 1 - 0 to c# vs prism. If I did not care which language is used for the mapping - why should I care about which language is used for the rest?

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  • Entity Framework 4.0 Databinding with sorting not working

    - by Mike Gates
    I want to do something that I thought would be very simple. I want to bind a generated Entity Framework EntityCollection to a WPF DataGrid. I also want this grid to be sortable. I have tried all kinds of things to make this happen, including using a CollectionViewSource. However, nothing seems to work. Using a normal CollectionViewSource around the EntityCollection gives me: 'System.Windows.Data.BindingListCollectionView' view does not support sorting. Ok...strange. I would have thought this would work. Next on the CollectionViewSource, I try setting: CollectionViewType="ListCollectionView" Great, sorting now works. But wait, I can't add or remove entities using the grid now, presumably because ListCollectionView doesn't support this with an entity framework context. So, I guess I need to capture events coming out of the datagrid in order to add or remove entities manually from my context. Now I can't find an event to capture to detect an add...! Why is this so hard? This should be the standard "demo" case that Microsoft should have designed around. Any ideas?

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  • Implement DDD and drawing the line between the an Entity and value object

    - by William
    I am implementing an EMR project. I would like to apply a DDD based approach to the problem. I have identified the "Patient" as being the core object of the system. I understand Patient would be an entity object as well as an aggregrate. I have also identified that every patient must have a "Doctor" and "Medical Records". The medical records would encompass Labs, XRays, Encounter.... I believe those would be entity objects as well. Let us take a Encounter for example. My implementation currently has a few fields as "String" properties, which are the complaint, assessment and plan. The other items necessary for an Encounter are vitals. I have implemented vitals as a value object. Given that it will be necessary to retrieve vitals without haveing to retrieve each Encounter then do vitals become part of the Encounter aggregate and patient aggregrate. I am assuming I could view the Encounter as an aggregrate, because other items are spwaned from the Encounter like prescriptions, lab orders, xrays. Is approach right that I am taking in identifying my entities and aggregates. In the case of vitals, they are specific to a patient, but outside of that there is not any other identity associated with them.

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  • Problem with custom Equality in Entity Framework

    - by Shimmy
    Hello! I am using Entity Framework in my application. I implemented with the partial class of an entity the IEquatable<T> interface: Partial Class Address : Implements IEquatable(Of Address) 'Other part generated Public Overloads Function Equals(ByVal other As Address) As Boolean _ Implements System.IEquatable(Of Address).Equals If ReferenceEquals(Me, other) Then Return True Return AddressId = other.AddressId End Function Public Overrides Function Equals(ByVal obj As Object) As Boolean If obj Is Nothing Then Return MyBase.Equals(obj) If TypeOf obj Is Address Then Return Equals(DirectCast(obj, Address)) Else Return False End Function Public Overrides Function GetHashCode() As Integer Return AddressId.GetHashCode End Function End Class Now in my code I use it this way: Sub Main() Using e As New CompleteKitchenEntities Dim job = e.Job.FirstOrDefault Dim address As New Address() job.Addresses.Add(address) Dim contains1 = job.Addresses.Contains(address) 'True e.SaveChanges() Dim contains2 = job.Addresses.Contains(address) 'False 'The problem is that I can't remove it: Dim removed = job.Addresses.Remoeve(address) 'False End Using End Sub Note (I checked in the debugger visualizer) that the EntityCollection class stores its entities in HashSet so it has to do with the GetHashCode function, I want it to depend on the ID so entities are compared by their IDs. Please help me find what's wrong in the GetHashCode function (by ID) and what can I change to make it work. Thanks a lot.

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  • Entity Framework: insert with one-to-one reference

    - by bomortensen
    Hi 'overflow! I'm having a bit trouble inserting into a mssql database using Entity Framework. There's two tables that I want to insert into, where one of table 1s fields is a foreign key in table2. This is the code I have so far: Media media = null; foreach(POI p in poiList) { media = new Media() { Path = p.ImagePath, Title = p.Title }; if (media != null && !context.Media.Any(me => me.Title == p.ImageTitle)) { context.AddToMedia(media); context.SaveChanges(); } PointOfInterest poi = new PointOfInterest() { Altitude = 2000.0, ID = p.ID, Latitude = p.Latitude, Longitude = p.Longitude, LatitudeRoute = p.LatitudeRoute, LongitudeRoute = p.LongitudeRoute, Description = p.Description, Title = p.Title, DefaultImageID = media.ID, }; context.AddToPointOfInterest(poi); } context.SaveChanges(); The following gives me this error: An object with the same key already exists in the ObjectStateManagerAn object with the same key already exists in the ObjectStateManager I'm still learning how to use the entity framework, so I don't even know if this would be the right approach to insert into two referenced tables. Can anyone enlighten me on this? :) Any help would be greatly appreciated! Thanks!

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  • Entity Framework & Binding syncronisation

    - by Jefim
    * EDIT * Sorry, I should make it clearer. Imagine I have an entity: public class MyObject { public string Name { get; set; } } And I have a ListBox: <ListBox x:Name="lbParts"> <ListBox.ItemTemplate> <DataTemplate> <TextBlock Text="{Binding Name}"/> </DataTemplate> </ListBox.ItemTemplate> </ListBox> I bind it to a collection in code-behind: ObjectQuery<MyObject> componentQuery = context.MyObjectSet; Binding b = new Binding(); b.Source = componentQuery; lbParts.SetBinding(ListBox.ItemsSourceProperty, b); And the on a button click I add an entity to the MyObjectSet: var myObject = new MyObject { Name = "Test" }; context.AddToMyObjectSet(myObject); Here is the problem - this object needs to update in the UI to. But it is not added there :( Help!

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  • getting expat to use .dtd for entity replacement in python

    - by nicolas78
    I'm trying to read in an xml file which looks like this <?xml version="1.0" encoding="ISO-8859-1"?> <!DOCTYPE dblp SYSTEM "dblp.dtd"> <dblp> <incollection> <author>Jos&eacute; A. Blakeley</author> </incollection> </dblp> The point that creates the problem looks is the Jos&eacute; A. Blakeley part: The parser calls its character handler twice, once with "Jos", once with " A. Blakeley". Now I understand this may be the correct behaviour if it doesn't know the eacute entity. However, this is defined in the dblp.dtd, which I have. I don't seem to be able to convince expat to use this file, though. All I can say is p = xml.parsers.expat.ParserCreate() # tried with and without following line p.SetParamEntityParsing(xml.parsers.expat.XML_PARAM_ENTITY_PARSING_ALWAYS) p.UseForeignDTD(True) f = open(dblp_file, "r") p.ParseFile(f) but expat still doesn't recognize my entity. Why is there no way to tell expat which DTD to use? I've tried putting the file into the same directory as the XML putting the file into the program's working directory replacing the reference in the xml file by an absolute path What am I missing? Thx.

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  • Understanding many to many relationships and Entity Framework

    - by Anders Svensson
    I'm trying to understand the Entity Framework, and I have a table "Users" and a table "Pages". These are related in a many-to-many relationship with a junction table "UserPages". First of all I'd like to know if I'm designing this relationship correctly using many-to-many: One user can visit multiple pages, and each page can be visited by multiple users..., so am I right in using many2many? Secondly, and more importantly, as I have understood m2m relationships, the User and Page tables should not repeat information. I.e. there should be only one record for each user and each page. But then in the entity framework, how am I able to add new visits to the same page for the same user? That is, I was thinking I could simply use the Count() method on the IEnumerable returned by a LINQ query to get the number of times a user has visited a certain page. But I see no way of doing that. In Linq to Sql I could access the junction table and add records there to reflect added visits to a certain page by a certain user, as many times as necessary. But in the EF I can't access the junction table. I can only go from User to a Pages collection and vice versa. I'm sure I'm misunderstanding relationships or something, but I just can't figure out how to model this. I could always have a Count column in the Page table, but as far as I have understood you're not supposed to design database tables like that, those values should be collected by queries... Please help me understand what I'm doing wrong...

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  • Howto use predicates in LINQ to Entities for Entity Framework objects

    - by user274947
    I'm using LINQ to Entities for Entity Framework objects in my Data Access Layer. My goal is to filter as much as I can from the database, without applying filtering logic on in-memory results. For that purpose Business Logic Layer passes a predicate to Data Access Layer. I mean Func<MyEntity, bool> So, if I use this predicate directly, like public IQueryable<MyEntity> GetAllMatchedEntities(Func<MyEntity, Boolean> isMatched) { return qry = _Context.MyEntities.Where(x => isMatched(x)); } I'm getting the exception [System.NotSupportedException] --- {"The LINQ expression node type 'Invoke' is not supported in LINQ to Entities."} Solution in that question suggests to use AsExpandable() method from LINQKit library. But again, using public IQueryable<MyEntity> GetAllMatchedEntities(Func<MyEntity, Boolean> isMatched) { return qry = _Context.MyEntities.AsExpandable().Where(x => isMatched(x)); } I'm getting the exception Unable to cast object of type 'System.Linq.Expressions.FieldExpression' to type 'System.Linq.Expressions.LambdaExpression' Is there way to use predicate in LINQ to Entities query for Entity Framework objects, so that it is correctly transformed it into a SQL statement. Thank you.

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  • Entity Filter child without include

    - by Lic
    i'm a C# developer and i have a trouble with Entity Framework 5. I have mapped my database with Entity using the default code generation strategy. In particolar there are three classes: menus, submenus and submenuitems. The relationships about three classes are: one menu - to many submenus one submenu - to many submenuitems. All classes have a boolean attribute called "Active". Now, i want to filter all the Menus with the SubMenus active, and the SubMenus with the SubMenuItems active. To get this i've tried this: var tmp = _model.Menus.Where(m => m.Active) .Select => new { Menu = x, SubMenu = x.SubMenus.Where(sb => sb.Active) .Select(y => new { SubMenu = y, SubMenuItem = y.SubMenuItems.Where(sbi => sbi.Active) }) }) .Select(x => x.Menu).ToList(); But didn't work. Someone can help me? Thank you for your help!

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  • Microsoft 2003 DNS sometimes cant query for some A pointers when their TTL expires

    - by Bq
    Warning Long question :) We have a win 2003 server with a DNS server, every now and then it cant provide us with some A pointers for a specific domain. I have a small script running which asks for SOA,NS and A records for the domain in question and sometimes when the TTL expires the DNS fails to get the A records again, a Clear Cache fixes the problem.. Have a look Here it worked when the TTL expired Thu Apr 29 15:24:20 METDST 2010 dig basefarm.net soa basefarm.net. 64908 IN SOA ns01.osl.basefarm.net. hostmaster.basefarm.net. 2010042613 86400 3600 2419200 600 ns01.osl.basefarm.net. 299 IN A 81.93.160.4 dig basefarm.net ns basefarm.net. 64908 IN NS ns01.sth.basefarm.net. basefarm.net. 64908 IN NS ns01.osl.basefarm.net. ns01.sth.basefarm.net. 299 IN A 80.76.149.76 ns01.osl.basefarm.net. 299 IN A 81.93.160.4 dig ns01.sth.basefarm.net a ns01.sth.basefarm.net. 299 IN A 80.76.149.76 The TTL expired for ns01.sth.basefarm.net and ns01.osl.basefarm.net but the DNS managed to get the new values (TTL 3600) Thu Apr 29 15:29:20 METDST 2010 dig basefarm.net soa basefarm.net. 64608 IN SOA ns01.osl.basefarm.net. hostmaster.basefarm.net. 2010042613 86400 3600 2419200 600 ns01.osl.basefarm.net. 3600 IN A 81.93.160.4 dig basefarm.net ns basefarm.net. 64608 IN NS ns01.sth.basefarm.net. basefarm.net. 64608 IN NS ns01.osl.basefarm.net. ns01.sth.basefarm.net. 3600 IN A 80.76.149.76 ns01.osl.basefarm.net. 3600 IN A 81.93.160.4 dig ns01.sth.basefarm.net a ns01.sth.basefarm.net. 3600 IN A 80.76.149.76 But then another time it fails, and we need to clear the dns cache for it to start working again... Thu Apr 29 17:24:23 METDST 2010 dig basefarm.net soa basefarm.net. 57705 IN SOA ns01.osl.basefarm.net. hostmaster.basefarm.net. 2010042613 86400 3600 2419200 600 ns01.osl.basefarm.net. 299 IN A 81.93.160.4 dig basefarm.net ns basefarm.net. 57705 IN NS ns01.sth.basefarm.net. basefarm.net. 57705 IN NS ns01.osl.basefarm.net. ns01.sth.basefarm.net. 299 IN A 80.76.149.76 ns01.osl.basefarm.net. 299 IN A 81.93.160.4 dig ns01.sth.basefarm.net a ns01.sth.basefarm.net. 299 IN A 80.76.149.76 The TTL expires but the DNS cant get the ip addresses for ns01.sth.basefarm.net and ns01.osl.basefarm.net Thu Apr 29 17:29:23 METDST 2010 dig basefarm.net soa basefarm.net. 57405 IN SOA ns01.osl.basefarm.net. hostmaster.basefarm.net. 2010042613 86400 3600 2419200 600 ns01.osl.basefarm.net. 3600 IN A 81.93.160.4 dig basefarm.net ns basefarm.net. 57405 IN NS ns01.sth.basefarm.net. basefarm.net. 57405 IN NS ns01.osl.basefarm.net. dig ns01.sth.basefarm.net a Lookup failed I'm really lost on this one and have tried asking Google but to no avail..

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  • Windows 2012 Server: Enable .NET 3.5

    - by Meengla
    I have a Windows 2012 Server which needs .NET 3.5 installed. For background info/solutions, please see this: http://sqlblog.com/blogs/sergio_govoni/archive/2013/07/13/how-to-install-netfx3-on-windows-server-2012-required-by-sql-server-2012.aspx I have tried this but it doesn't work for me. Here is what I am trying: Using a Windows 2012 ISO file, 'mount' on the 2012 Server as 'D' drive and then tried both GUI and Command prompt. In case of GUI, I specified the 'alternate source' path to the D drive's 'source/sxs folder but that failed without giving enough info. In case of the command prompt, here is what's happening: dism /online /enable-feature /featurename:NetFx3 /source:d:\sources\sxs I get error: Installed but Parent feature not enabled. So I tried another approached: dism /online /enable-feature /featurename:NetFx3 /all /source:d:\sources\sxs the above command, per http://blogs.technet.com/b/askcore/archive/2012/05/14/windows-8-and-net-framework-3-5.aspx is supposed to enable parent elements; but running this I get error like 'source not found'. Is there some error in my second command? What else I could do? This is Windows 2012 Server Standard edition. Thanks!

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