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  • What&rsquo;s New in ASP.NET 4.0 Part Two: WebForms and Visual Studio Enhancements

    - by Rick Strahl
    In the last installment I talked about the core changes in the ASP.NET runtime that I’ve been taking advantage of. In this column, I’ll cover the changes to the Web Forms engine and some of the cool improvements in Visual Studio that make Web and general development easier. WebForms The WebForms engine is the area that has received most significant changes in ASP.NET 4.0. Probably the most widely anticipated features are related to managing page client ids and of ViewState on WebForm pages. Take Control of Your ClientIDs Unique ClientID generation in ASP.NET has been one of the most complained about “features” in ASP.NET. Although there’s a very good technical reason for these unique generated ids - they guarantee unique ids for each and every server control on a page - these unique and generated ids often get in the way of client-side JavaScript development and CSS styling as it’s often inconvenient and fragile to work with the long, generated ClientIDs. In ASP.NET 4.0 you can now specify an explicit client id mode on each control or each naming container parent control to control how client ids are generated. By default, ASP.NET generates mangled client ids for any control contained in a naming container (like a Master Page, or a User Control for example). The key to ClientID management in ASP.NET 4.0 are the new ClientIDMode and ClientIDRowSuffix properties. ClientIDMode supports four different ClientID generation settings shown below. For the following examples, imagine that you have a Textbox control named txtName inside of a master page control container on a WebForms page. <%@Page Language="C#"      MasterPageFile="~/Site.Master"     CodeBehind="WebForm2.aspx.cs"     Inherits="WebApplication1.WebForm2"  %> <asp:Content ID="content"  ContentPlaceHolderID="content"               runat="server"               ClientIDMode="Static" >       <asp:TextBox runat="server" ID="txtName" /> </asp:Content> The four available ClientIDMode values are: AutoID This is the existing behavior in ASP.NET 1.x-3.x where full naming container munging takes place. <input name="ctl00$content$txtName" type="text"        id="ctl00_content_txtName" /> This should be familiar to any ASP.NET developer and results in fairly unpredictable client ids that can easily change if the containership hierarchy changes. For example, removing the master page changes the name in this case, so if you were to move a block of script code that works against the control to a non-Master page, the script code immediately breaks. Static This option is the most deterministic setting that forces the control’s ClientID to use its ID value directly. No naming container naming at all is applied and you end up with clean client ids: <input name="ctl00$content$txtName"         type="text" id="txtName" /> Note that the name property which is used for postback variables to the server still is munged, but the ClientID property is displayed simply as the ID value that you have assigned to the control. This option is what most of us want to use, but you have to be clear on that because it can potentially cause conflicts with other controls on the page. If there are several instances of the same naming container (several instances of the same user control for example) there can easily be a client id naming conflict. Note that if you assign Static to a data-bound control, like a list child control in templates, you do not get unique ids either, so for list controls where you rely on unique id for child controls, you’ll probably want to use Predictable rather than Static. I’ll write more on this a little later when I discuss ClientIDRowSuffix. Predictable The previous two values are pretty self-explanatory. Predictable however, requires some explanation. To me at least it’s not in the least bit predictable. MSDN defines this value as follows: This algorithm is used for controls that are in data-bound controls. The ClientID value is generated by concatenating the ClientID value of the parent naming container with the ID value of the control. If the control is a data-bound control that generates multiple rows, the value of the data field specified in the ClientIDRowSuffix property is added at the end. For the GridView control, multiple data fields can be specified. If the ClientIDRowSuffix property is blank, a sequential number is added at the end instead of a data-field value. Each segment is separated by an underscore character (_). The key that makes this value a bit confusing is that it relies on the parent NamingContainer’s ClientID to build its own ClientID value. This effectively means that the value is not predictable at all but rather very tightly coupled to the parent naming container’s ClientIDMode setting. For my simple textbox example, if the ClientIDMode property of the parent naming container (Page in this case) is set to “Predictable” you’ll get this: <input name="ctl00$content$txtName" type="text"         id="content_txtName" /> which gives an id that based on walking up to the currently active naming container (the MasterPage content container) and starting the id formatting from there downward. Think of this as a semi unique name that’s guaranteed unique only for the naming container. If, on the other hand, the Page is set to “AutoID” you get the following with Predictable on txtName: <input name="ctl00$content$txtName" type="text"         id="ctl00_content_txtName" /> The latter is effectively the same as if you specified AutoID because it inherits the AutoID naming from the Page and Content Master Page control of the page. But again - predictable behavior always depends on the parent naming container and how it generates its id, so the id may not always be exactly the same as the AutoID generated value because somewhere in the NamingContainer chain the ClientIDMode setting may be set to a different value. For example, if you had another naming container in the middle that was set to Static you’d end up effectively with an id that starts with the NamingContainers id rather than the whole ctl000_content munging. The most common use for Predictable is likely to be for data-bound controls, which results in each data bound item getting a unique ClientID. Unfortunately, even here the behavior can be very unpredictable depending on which data-bound control you use - I found significant differences in how template controls in a GridView behave from those that are used in a ListView control. For example, GridView creates clean child ClientIDs, while ListView still has a naming container in the ClientID, presumably because of the template container on which you can’t set ClientIDMode. Predictable is useful, but only if all naming containers down the chain use this setting. Otherwise you’re right back to the munged ids that are pretty unpredictable. Another property, ClientIDRowSuffix, can be used in combination with ClientIDMode of Predictable to force a suffix onto list client controls. For example: <asp:GridView runat="server" ID="gvItems"              AutoGenerateColumns="false"             ClientIDMode="Static"              ClientIDRowSuffix="Id">     <Columns>     <asp:TemplateField>         <ItemTemplate>             <asp:Label runat="server" id="txtName"                        Text='<%# Eval("Name") %>'                   ClientIDMode="Predictable"/>         </ItemTemplate>     </asp:TemplateField>     <asp:TemplateField>         <ItemTemplate>         <asp:Label runat="server" id="txtId"                     Text='<%# Eval("Id") %>'                     ClientIDMode="Predictable" />         </ItemTemplate>     </asp:TemplateField>     </Columns>  </asp:GridView> generates client Ids inside of a column in the master page described earlier: <td>     <span id="txtName_0">Rick</span> </td> where the value after the underscore is the ClientIDRowSuffix field - in this case “Id” of the item data bound to the control. Note that all of the child controls require ClientIDMode=”Predictable” in order for the ClientIDRowSuffix to be applied, and the parent GridView controls need to be set to Static either explicitly or via Naming Container inheritance to give these simple names. It’s a bummer that ClientIDRowSuffix doesn’t work with Static to produce this automatically. Another real problem is that other controls process the ClientIDMode differently. For example, a ListView control processes the Predictable ClientIDMode differently and produces the following with the Static ListView and Predictable child controls: <span id="ctrl0_txtName_0">Rick</span> I couldn’t even figure out a way using ClientIDMode to get a simple ID that also uses a suffix short of falling back to manually generated ids using <%= %> expressions instead. Given the inconsistencies inside of list controls using <%= %>, ids for the ListView might not be a bad idea anyway. Inherit The final setting is Inherit, which is the default for all controls except Page. This means that controls by default inherit the parent naming container’s ClientIDMode setting. For more detailed information on ClientID behavior and different scenarios you can check out a blog post of mine on this subject: http://www.west-wind.com/weblog/posts/54760.aspx. ClientID Enhancements Summary The ClientIDMode property is a welcome addition to ASP.NET 4.0. To me this is probably the most useful WebForms feature as it allows me to generate clean IDs simply by setting ClientIDMode="Static" on either the page or inside of Web.config (in the Pages section) which applies the setting down to the entire page which is my 95% scenario. For the few cases when it matters - for list controls and inside of multi-use user controls or custom server controls) - I can use Predictable or even AutoID to force controls to unique names. For application-level page development, this is easy to accomplish and provides maximum usability for working with client script code against page controls. ViewStateMode Another area of large criticism for WebForms is ViewState. ViewState is used internally by ASP.NET to persist page-level changes to non-postback properties on controls as pages post back to the server. It’s a useful mechanism that works great for the overall mechanics of WebForms, but it can also cause all sorts of overhead for page operation as ViewState can very quickly get out of control and consume huge amounts of bandwidth in your page content. ViewState can also wreak havoc with client-side scripting applications that modify control properties that are tracked by ViewState, which can produce very unpredictable results on a Postback after client-side updates. Over the years in my own development, I’ve often turned off ViewState on pages to reduce overhead. Yes, you lose some functionality, but you can easily implement most of the common functionality in non-ViewState workarounds. Relying less on heavy ViewState controls and sticking with simpler controls or raw HTML constructs avoids getting around ViewState problems. In ASP.NET 3.x and prior, it wasn’t easy to control ViewState - you could turn it on or off and if you turned it off at the page or web.config level, you couldn’t turn it back on for specific controls. In short, it was an all or nothing approach. With ASP.NET 4.0, the new ViewStateMode property gives you more control. It allows you to disable ViewState globally either on the page or web.config level and then turn it back on for specific controls that might need it. ViewStateMode only works when EnableViewState="true" on the page or web.config level (which is the default). You can then use ViewStateMode of Disabled, Enabled or Inherit to control the ViewState settings on the page. If you’re shooting for minimal ViewState usage, the ideal situation is to set ViewStateMode to disabled on the Page or web.config level and only turn it back on particular controls: <%@Page Language="C#"      CodeBehind="WebForm2.aspx.cs"     Inherits="Westwind.WebStore.WebForm2"        ClientIDMode="Static"                ViewStateMode="Disabled"     EnableViewState="true"  %> <!-- this control has viewstate  --> <asp:TextBox runat="server" ID="txtName"  ViewStateMode="Enabled" />       <!-- this control has no viewstate - it inherits  from parent container --> <asp:TextBox runat="server" ID="txtAddress" /> Note that the EnableViewState="true" at the Page level isn’t required since it’s the default, but it’s important that the value is true. ViewStateMode has no effect if EnableViewState="false" at the page level. The main benefit of ViewStateMode is that it allows you to more easily turn off ViewState for most of the page and enable only a few key controls that might need it. For me personally, this is a perfect combination as most of my WebForm apps can get away without any ViewState at all. But some controls - especially third party controls - often don’t work well without ViewState enabled, and now it’s much easier to selectively enable controls rather than the old way, which required you to pretty much turn off ViewState for all controls that you didn’t want ViewState on. Inline HTML Encoding HTML encoding is an important feature to prevent cross-site scripting attacks in data entered by users on your site. In order to make it easier to create HTML encoded content, ASP.NET 4.0 introduces a new Expression syntax using <%: %> to encode string values. The encoding expression syntax looks like this: <%: "<script type='text/javascript'>" +     "alert('Really?');</script>" %> which produces properly encoded HTML: &lt;script type=&#39;text/javascript&#39; &gt;alert(&#39;Really?&#39;);&lt;/script&gt; Effectively this is a shortcut to: <%= HttpUtility.HtmlEncode( "<script type='text/javascript'>" + "alert('Really?');</script>") %> Of course the <%: %> syntax can also evaluate expressions just like <%= %> so the more common scenario applies this expression syntax against data your application is displaying. Here’s an example displaying some data model values: <%: Model.Address.Street %> This snippet shows displaying data from your application’s data store or more importantly, from data entered by users. Anything that makes it easier and less verbose to HtmlEncode text is a welcome addition to avoid potential cross-site scripting attacks. Although I listed Inline HTML Encoding here under WebForms, anything that uses the WebForms rendering engine including ASP.NET MVC, benefits from this feature. ScriptManager Enhancements The ASP.NET ScriptManager control in the past has introduced some nice ways to take programmatic and markup control over script loading, but there were a number of shortcomings in this control. The ASP.NET 4.0 ScriptManager has a number of improvements that make it easier to control script loading and addresses a few of the shortcomings that have often kept me from using the control in favor of manual script loading. The first is the AjaxFrameworkMode property which finally lets you suppress loading the ASP.NET AJAX runtime. Disabled doesn’t load any ASP.NET AJAX libraries, but there’s also an Explicit mode that lets you pick and choose the library pieces individually and reduce the footprint of ASP.NET AJAX script included if you are using the library. There’s also a new EnableCdn property that forces any script that has a new WebResource attribute CdnPath property set to a CDN supplied URL. If the script has this Attribute property set to a non-null/empty value and EnableCdn is enabled on the ScriptManager, that script will be served from the specified CdnPath. [assembly: WebResource(    "Westwind.Web.Resources.ww.jquery.js",    "application/x-javascript",    CdnPath =  "http://mysite.com/scripts/ww.jquery.min.js")] Cool, but a little too static for my taste since this value can’t be changed at runtime to point at a debug script as needed, for example. Assembly names for loading scripts from resources can now be simple names rather than fully qualified assembly names, which make it less verbose to reference scripts from assemblies loaded from your bin folder or the assembly reference area in web.config: <asp:ScriptManager runat="server" id="Id"          EnableCdn="true"         AjaxFrameworkMode="disabled">     <Scripts>         <asp:ScriptReference          Name="Westwind.Web.Resources.ww.jquery.js"         Assembly="Westwind.Web" />     </Scripts>        </asp:ScriptManager> The ScriptManager in 4.0 also supports script combining via the CompositeScript tag, which allows you to very easily combine scripts into a single script resource served via ASP.NET. Even nicer: You can specify the URL that the combined script is served with. Check out the following script manager markup that combines several static file scripts and a script resource into a single ASP.NET served resource from a static URL (allscripts.js): <asp:ScriptManager runat="server" id="Id"          EnableCdn="true"         AjaxFrameworkMode="disabled">     <CompositeScript          Path="~/scripts/allscripts.js">         <Scripts>             <asp:ScriptReference                    Path="~/scripts/jquery.js" />             <asp:ScriptReference                    Path="~/scripts/ww.jquery.js" />             <asp:ScriptReference            Name="Westwind.Web.Resources.editors.js"                 Assembly="Westwind.Web" />         </Scripts>     </CompositeScript> </asp:ScriptManager> When you render this into HTML, you’ll see a single script reference in the page: <script src="scripts/allscripts.debug.js"          type="text/javascript"></script> All you need to do to make this work is ensure that allscripts.js and allscripts.debug.js exist in the scripts folder of your application - they can be empty but the file has to be there. This is pretty cool, but you want to be real careful that you use unique URLs for each combination of scripts you combine or else browser and server caching will easily screw you up royally. The script manager also allows you to override native ASP.NET AJAX scripts now as any script references defined in the Scripts section of the ScriptManager trump internal references. So if you want custom behavior or you want to fix a possible bug in the core libraries that normally are loaded from resources, you can now do this simply by referencing the script resource name in the Name property and pointing at System.Web for the assembly. Not a common scenario, but when you need it, it can come in real handy. Still, there are a number of shortcomings in this control. For one, the ScriptManager and ClientScript APIs still have no common entry point so control developers are still faced with having to check and support both APIs to load scripts so that controls can work on pages that do or don’t have a ScriptManager on the page. The CdnUrl is static and compiled in, which is very restrictive. And finally, there’s still no control over where scripts get loaded on the page - ScriptManager still injects scripts into the middle of the HTML markup rather than in the header or optionally the footer. This, in turn, means there is little control over script loading order, which can be problematic for control developers. MetaDescription, MetaKeywords Page Properties There are also a number of additional Page properties that correspond to some of the other features discussed in this column: ClientIDMode, ClientTarget and ViewStateMode. Another minor but useful feature is that you can now directly access the MetaDescription and MetaKeywords properties on the Page object to set the corresponding meta tags programmatically. Updating these values programmatically previously required either <%= %> expressions in the page markup or dynamic insertion of literal controls into the page. You can now just set these properties programmatically on the Page object in any Control derived class on the page or the Page itself: Page.MetaKeywords = "ASP.NET,4.0,New Features"; Page.MetaDescription = "This article discusses the new features in ASP.NET 4.0"; Note, that there’s no corresponding ASP.NET tag for the HTML Meta element, so the only way to specify these values in markup and access them is via the @Page tag: <%@Page Language="C#"      CodeBehind="WebForm2.aspx.cs"     Inherits="Westwind.WebStore.WebForm2"      ClientIDMode="Static"                MetaDescription="Article that discusses what's                      new in ASP.NET 4.0"     MetaKeywords="ASP.NET,4.0,New Features" %> Nothing earth shattering but quite convenient. Visual Studio 2010 Enhancements for Web Development For Web development there are also a host of editor enhancements in Visual Studio 2010. Some of these are not Web specific but they are useful for Web developers in general. Text Editors Throughout Visual Studio 2010, the text editors have all been updated to a new core engine based on WPF which provides some interesting new features for various code editors including the nice ability to zoom in and out with Ctrl-MouseWheel to quickly change the size of text. There are many more API options to control the editor and although Visual Studio 2010 doesn’t yet use many of these features, we can look forward to enhancements in add-ins and future editor updates from the various language teams that take advantage of the visual richness that WPF provides to editing. On the negative side, I’ve noticed that occasionally the code editor and especially the HTML and JavaScript editors will lose the ability to use various navigation keys like arrows, back and delete keys, which requires closing and reopening the documents at times. This issue seems to be well documented so I suspect this will be addressed soon with a hotfix or within the first service pack. Overall though, the code editors work very well, especially given that they were re-written completely using WPF, which was one of my big worries when I first heard about the complete redesign of the editors. Multi-Targeting Visual Studio now targets all versions of the .NET framework from 2.0 forward. You can use Visual Studio 2010 to work on your ASP.NET 2, 3.0 and 3.5 applications which is a nice way to get your feet wet with the new development environment without having to make changes to existing applications. It’s nice to have one tool to work in for all the different versions. Multi-Monitor Support One cool feature of Visual Studio 2010 is the ability to drag windows out of the Visual Studio environment and out onto the desktop including onto another monitor easily. Since Web development often involves working with a host of designers at the same time - visual designer, HTML markup window, code behind and JavaScript editor - it’s really nice to be able to have a little more screen real estate to work on each of these editors. Microsoft made a welcome change in the environment. IntelliSense Snippets for HTML and JavaScript Editors The HTML and JavaScript editors now finally support IntelliSense scripts to create macro-based template expansions that have been in the core C# and Visual Basic code editors since Visual Studio 2005. Snippets allow you to create short XML-based template definitions that can act as static macros or real templates that can have replaceable values that can be embedded into the expanded text. The XML syntax for these snippets is straight forward and it’s pretty easy to create custom snippets manually. You can easily create snippets using XML and store them in your custom snippets folder (C:\Users\rstrahl\Documents\Visual Studio 2010\Code Snippets\Visual Web Developer\My HTML Snippets and My JScript Snippets), but it helps to use one of the third-party tools that exist to simplify the process for you. I use SnippetEditor, by Bill McCarthy, which makes short work of creating snippets interactively (http://snippeteditor.codeplex.com/). Note: You may have to manually add the Visual Studio 2010 User specific Snippet folders to this tool to see existing ones you’ve created. Code snippets are some of the biggest time savers and HTML editing more than anything deals with lots of repetitive tasks that lend themselves to text expansion. Visual Studio 2010 includes a slew of built-in snippets (that you can also customize!) and you can create your own very easily. If you haven’t done so already, I encourage you to spend a little time examining your coding patterns and find the repetitive code that you write and convert it into snippets. I’ve been using CodeRush for this for years, but now you can do much of the basic expansion natively for HTML and JavaScript snippets. jQuery Integration Is Now Native jQuery is a popular JavaScript library and recently Microsoft has recently stated that it will become the primary client-side scripting technology to drive higher level script functionality in various ASP.NET Web projects that Microsoft provides. In Visual Studio 2010, the default full project template includes jQuery as part of a new project including the support files that provide IntelliSense (-vsdoc files). IntelliSense support for jQuery is now also baked into Visual Studio 2010, so unlike Visual Studio 2008 which required a separate download, no further installs are required for a rich IntelliSense experience with jQuery. Summary ASP.NET 4.0 brings many useful improvements to the platform, but thankfully most of the changes are incremental changes that don’t compromise backwards compatibility and they allow developers to ease into the new features one feature at a time. None of the changes in ASP.NET 4.0 or Visual Studio 2010 are monumental or game changers. The bigger features are language and .NET Framework changes that are also optional. This ASP.NET and tools release feels more like fine tuning and getting some long-standing kinks worked out of the platform. It shows that the ASP.NET team is dedicated to paying attention to community feedback and responding with changes to the platform and development environment based on this feedback. If you haven’t gotten your feet wet with ASP.NET 4.0 and Visual Studio 2010, there’s no reason not to give it a shot now - the ASP.NET 4.0 platform is solid and Visual Studio 2010 works very well for a brand new release. Check it out. © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  

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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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  • Changing an HTML Form's Target with jQuery

    - by Rick Strahl
    This is a question that comes up quite frequently: I have a form with several submit or link buttons and one or more of the buttons needs to open a new Window. How do I get several buttons to all post to the right window? If you're building ASP.NET forms you probably know that by default the Web Forms engine sends button clicks back to the server as a POST operation. A server form has a <form> tag which expands to this: <form method="post" action="default.aspx" id="form1"> Now you CAN change the target of the form and point it to a different window or frame, but the problem with that is that it still affects ALL submissions of the current form. If you multiple buttons/links and they need to go to different target windows/frames you can't do it easily through the <form runat="server"> tag. Although this discussion uses ASP.NET WebForms as an example, realistically this is a general HTML problem although likely more common in WebForms due to the single form metaphor it uses. In ASP.NET MVC for example you'd have more options by breaking out each button into separate forms with its own distinct target tag. However, even with that option it's not always possible to break up forms - for example if multiple targets are required but all targets require the same form data to the be posted. A common scenario here is that you might have a button (or link) that you click where you still want some server code to fire but at the end of the request you actually want to display the content in a new window. A common operation where this happens is report generation: You click a button and the server generates a report say in PDF format and you then want to display the PDF result in a new window without killing the content in the current window. Assuming you have other buttons on the same Page that need to post to base window how do you get the button click to go to a new window? Can't  you just use a LinkButton or other Link Control? At first glance you might think an easy way to do this is to use an ASP.NET LinkButton to do this - after all a LinkButton creates a hyper link that CAN accept a target and it also posts back to the server, right? However, there's no Target property, although you can set the target HTML attribute easily enough. Code like this looks reasonable: <asp:LinkButton runat="server" ID="btnNewTarget" Text="New Target" target="_blank" OnClick="bnNewTarget_Click" /> But if you try this you'll find that it doesn't work. Why? Because ASP.NET creates postbacks with JavaScript code that operates on the current window/frame: <a id="btnNewTarget" target="_blank" href="javascript:__doPostBack(&#39;btnNewTarget&#39;,&#39;&#39;)">New Target</a> What happens with a target tag is that before the JavaScript actually executes a new window is opened and the focus shifts to the new window. The new window of course is empty and has no __doPostBack() function nor access to the old document. So when you click the link a new window opens but the window remains blank without content - no server postback actually occurs. Natch that idea. Setting the Form Target for a Button Control or LinkButton So, in order to send Postback link controls and buttons to another window/frame, both require that the target of the form gets changed dynamically when the button or link is clicked. Luckily this is rather easy to do however using a little bit of script code and jQuery. Imagine you have two buttons like this that should go to another window: <asp:LinkButton runat="server" ID="btnNewTarget" Text="New Target" OnClick="ClickHandler" /> <asp:Button runat="server" ID="btnButtonNewTarget" Text="New Target Button" OnClick="ClickHandler" /> ClickHandler in this case is any routine that generates the output you want to display in the new window. Generally this output will not come from the current page markup but is generated externally - like a PDF report or some report generated by another application component or tool. The output generally will be either generated by hand or something that was generated to disk to be displayed with Response.Redirect() or Response.TransmitFile() etc. Here's the dummy handler that just generates some HTML by hand and displays it: protected void ClickHandler(object sender, EventArgs e) { // Perform some operation that generates HTML or Redirects somewhere else Response.Write("Some custom output would be generated here (PDF, non-Page HTML etc.)"); // Make sure this response doesn't display the page content // Call Response.End() or Response.Redirect() Response.End(); } To route this oh so sophisticated output to an alternate window for both the LinkButton and Button Controls, you can use the following simple script code: <script type="text/javascript"> $("#btnButtonNewTarget,#btnNewTarget").click(function () { $("form").attr("target", "_blank"); }); </script> So why does this work where the target attribute did not? The difference here is that the script fires BEFORE the target is changed to the new window. When you put a target attribute on a link or form the target is changed as the very first thing before the link actually executes. IOW, the link literally executes in the new window when it's done this way. By attaching a click handler, though we're not navigating yet so all the operations the script code performs (ie. __doPostBack()) and the collection of Form variables to post to the server all occurs in the current page. By changing the target from within script code the target change fires as part of the form submission process which means it runs in the correct context of the current page. IOW - the input for the POST is from the current page, but the output is routed to a new window/frame. Just what we want in this scenario. Voila you can dynamically route output to the appropriate window.© Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  HTML  jQuery  

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  • AJAX Control Toolkit - Incompatibility with HTMLEditor and UpdatePanel

    - by Guilherme Cardoso
    Unfortunately HTMLEditor component of AJAX Control Toolkit is not compatible with the UpdatePanel. The problem is when we use accents with the Mozilla Firefox browser and HTMLEditor is inside an UpdatePanel. Letters that contain accents are left with an unknown character (so is stored in the database or even returned a PostBack). Can be tested using Mozilla Firefox on the site of the ASP.NET AJAX Control Toolkit.  Write a word with accents and go to "Submit Content": http://www.asp.net/AJAX/AjaxControlToolkit/Samples/HTMLEditor/HTMLEditor.aspx As an alternative to this problem there are multiple component Rich Text Editors, some using jQuery and others not. Queneeshas provided us a list of 10 components that can be viewed here: http://www.queness.com/post/212/10-jquery-and-non-jquery-javascript-rich-text-editors Hopefully next release of the AJAX Control Toolkit, this inconsistency and others (like the ModalPopup Extender that already referenced in my blog) are resolved once and for all. This is because there are more updated versions prior to that do not have these problems, and with the passing of time some parts were coming into conflict. If you know of any alternative or want to know at this problem, you can visit the topic I created the section of the AJAX Control Toolkit in ASP.NET forum: http://forums.asp.net/p/1548141/3848763.aspx

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  • How should data be passed between client-side Javascript and C# code behind an ASP.NET app?

    - by ctck
    I'm looking for the most efficient / standard way of passing data between client-side Javascript code and C# code behind an ASP.NET application. I've been using the following methods to achieve this but they all feel a bit of a fudge. To pass data from Javascript to the C# code is by setting hidden ASP variables and triggering a postback: <asp:HiddenField ID="RandomList" runat="server" /> function SetDataField(data) { document.getElementById('<%=RandomList.ClientID%>').value = data; } Then in the C# code I collect the list: protected void GetData(object sender, EventArgs e) { var _list = RandomList.value; } Going back the other way I often use either ScriptManager to register a function and pass it data during Page_Load: ScriptManager.RegisterStartupScript(this.GetType(), "Set","get("Test();",true); or I add attributes to controls before a post back or during the initialization or pre-rendering stages: Btn.Attributes.Add("onclick", "DisplayMessage("Hello");"); These methods have served me well and do the job, but they just dont feel complete. Is there a more standard way of passing data between client side Javascript and C# backend code? Ive seen some posts like this one that describe HtmlElement class; is this something I should look into?

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  • AuthResend query string being appended to URL

    - by Alastair Pitts
    One of our clients is having an issue where POSTBACK seems to be broken when they connect to our Sharepoint application. When they navigate to a URL, an erroneous query string gets appended to the URL, so the end of the URL becomes: .../default.aspx&AuthResend1908BC2350124b5095AB75012FA405BA this isn't something that appears on any other clients computers or ours internally. This is the only difference and it seems to be breaking their pages. I had a quick Google and it seems that it's to do with a Microsoft ISA server, but I have no experience with that. Is this a bug or setting on their ISA server?

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  • Using ASP.NET C# and Javascript

    - by ctck
    I'm looking for the most efficient / standardized way of passing data between client javascript code and C# code behind in an ASP.NET application. Currently ive been using the following methods to achieve this but they all feel a bit like a fudge. The way i pass data from javascript to the C# code behind is by setting hidden asp variables and triggering a postback <asp:HiddenField ID="RandomList" runat="server" /> function SetDataField(data) { document.getElementById('<%=RandomList.ClientID%>').value = data; } Then in C# code i collect the list protected void GetData(object sender, EventArgs e) { var _list = RandomList.value; } Going back the other way i often use either scriptmanager to register a function and pass it data during Page_Load: ScriptManager.RegisterStartupScript(this.GetType(), "Set","get("Test();",true); or i add attributes to controls before a post back or during Initialization / pre rendering stages: Btn.Attributes.Add("onclick", "DisplayMessage("Hello");"); These methods have served me well and do the job. However they just dont feel complete. Is there a more standardized way of passing data between client side markup / javascript and backend code. Ive seen some posts like this one: Injecting JavaScrip : StackOverflow that describe HtmlElement class. Is this something is should look into? Thanks everyone for your time.

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  • How to disable an ASP.NET linkbutton when clicked

    - by Jeff Widmer
    Scenario: User clicks a LinkButton in your ASP.NET page and you want to disable it immediately using javascript so that the user cannot accidentally click it again.  I wrote about disabling a regular submit button here: How to disable an ASP.NET button when clicked.  But the method described in the other blog post does not work for disabling a LinkButton.  This is because the Post Back Event Reference is called using a snippet of javascript from within the href of the anchor tag: <a id="MyContrl_MyButton" href="javascript:__doPostBack('MyContrl$MyButton','')">My Button</a> If you try to add an onclick event to disable the button, even though the button will become disabled, the href will still be allowed to be clicked multiple times (causing duplicate form submissions).  To get around this, in addition to disabling the button in the onclick javascript, you can set the href to “#” to prevent it from doing anything on the page.  You can add this to the LinkButton from your code behind like this: MyButton.Attributes.Add("onclick", "this.href='#';this.disabled=true;" + Page.ClientScript.GetPostBackEventReference(MyButton, "").ToString()); This code adds javascript to set the href to “#” and then disable the button in the onclick event of the LinkButton by appending to the Attributes collection of the ASP.NET LinkButton control.  Then the Post Back Event Reference for the button is called right after disabling the button.  Make sure you add the Post Back Event Reference to the onclick because now that you are changing the anchor href, the button still needs to perform the original postback. With the code above now the button onclick event will look something like this: onclick="this.href='#';this.disabled=true;__doPostBack('MyContrl$MyButton','');" The anchor href is set to “#”, the linkbutton is disabled, AND then the button post back method is called. Technorati Tags: ASP.NET LinkButton

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  • Checking All Checkboxes in a GridView Using jQuery

    In May 2006 I wrote two articles that showed how to add a column of checkboxes to a GridView and offer the ability for users to check (or uncheck) all checkboxes in the column with a single click of the mouse. The first article, Checking All CheckBoxes in a GridView, showed how to add "Check All" and "Uncheck All" buttons to the page above the GridView that, when clicked, checked or unchecked all of the checkboxes. The second article, Checking All CheckBoxes in a GridView Using Client-Side Script and a Check All CheckBox, detailed how to add a checkbox to the checkbox column in the grid's header row that would check or uncheck all checkboxes in the column. Both articles showed how to implement such functionality on the client-side, thereby removing the need for a postback. The JavaScript presented in these two previous articles still works, but the techniques used are a bit antiquated and hamfisted given the advances made in JavaScript programming over the past few years. For instance, the script presented in the previous articles uses server-side code in the GridView's DataBound event handler to assign a client-side onclick event handler to each checkbox. While this works, it violates the tenets of unobtrusive JavaScript, which is a design guideline for JavaScript programming that encourages a clean separation of functionality from presentation. (Ideally, event handlers for HTML elements are defined in script.) Also, the quantity of JavaScript used in the two previous articles is quite hefty compared to the amount of code that would be needed using modern JavaScript libraries like jQuery. This article presents updated JavaScript for checking (and unchecking) all checkboxes within a GridView. The two examples from the previous articles - checking/unchecking all checkboxes using a button and checking/unchecking all checkboxes using a checkbox in the header row - are reimplemented here using jQuery and unobtrusive JavaScript techniques. Read on to learn more! Read More >

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  • ASP.Net Fails to Detect IE10 without .Net Hotfix

    - by Ben Barreth
    Benny Mathew recently alerted us that he couldn’t create, edit or delete posts on GeeksWithBlogs in IE10 (Windows 8). It turns out the problem is that ASP.Net fails to detect IE10 causing a javascript error on postback. We’ll be applying a hotfix to the .Net framework on GWB shortly to fix this issue. In the meantime you can use the simple workaround outlined below. (Note that if you create posts using Windows Live Writer you won’t have this issue creating posts). Log into your GWB Account and go to the “Posts” page. Hit F12 to bring up the developer window in IE10. Click on the ‘Browser Mode’ option and change it to IE9. You should now be able to create/edit/delete posts in GWB. Note this also fixes any other sites in IE10 that might not yet have the hotfix applied. You can tell if the hotfix is the likely culprit if you’re using IE10 and see the following error in the Web Developers Console area: SCRIPT5009: '__doPostBack' is undefined Let us know ASAP if there are other issues you are experiencing that aren’t fixed by this workaround!

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  • Enable file download via redirect in IE7

    - by Christian W
    Our application enables our customers to download files to their computer. The way I have implemented it is using asp.net with a dropdown. When the user clicks the dropdown they get the choice of "PDF","Powerpoint", and a couple of other choices depending on circumstances. Then, in postback depending on the choice the user made, it will return a file (changing the content-header and such and then bitbanging a file to the user). This works perfectly in all browsers, but IE7 complains that this is a security risk and blocks the download. Is there any way for the users to authorize downloads from our webapplication?

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  • getting a 404/403 error for payment gateway

    - by Obay Ouano
    We are setting up an online payment facility using a payment gateway. After the payment gateway finishes processing the credit card details for a payment, the user is redirected to a "403 Forbidden" page. The logs show: [MY_IP_ADDRESS_HERE] - - [SOME_DATE_HERE] "GET /POSTBACK_URL.php?txnid=1338434567&result=failure&reason=The+remote+server+returned+an+error%3a+(404)+Not+Found.&digest=7a115270c56df5945c43ad86e56b2e930a3cfd50 HTTP/1.1" 404 - "PAYMENT_GATEWAY_URL_HERE" "BROWSER_DETAILS_HERE" It means that when the PAYMENT_GATEWAY_URL attempts to open our POSTBACK_URL, it gets a 404 error, is that correct? But why does the page say "403 Forbidden"? Anyway, we tried to copy-paste that same URL into the browser window, and the page is opened successfully, with our programmed error notification message. So, why couldn't it be opened when the payment gateway tried to redirect to it, but we could? Is this some sort of permissions issue? If so, the postback URL's file permissions are already 755. What am I missing?

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  • Calling a webservice via Javascript

    - by jeroenb
    If you want to consume a webservice, it's not allways necessary to do a postback. It's even not that hard! 1. Webservice You have to add the scriptservice attribute to the webservice. [System.Web.Script.Services.ScriptService]public class PersonsInCompany : System.Web.Services.WebService { Create a WebMethod [WebMethod] public Person GetPersonByFirstName(string name) { List<Person> personSelect = persons.Where(p => p.FirstName.ToLower().StartsWith(name.ToLower())).ToList(); if (personSelect.Count > 0) return personSelect.First(); else return null; } 2. webpage Add reference to your service to your scriptmanager <script type="text/javascript"> function GetPersonInCompany() { var val = document.getElementById("MainContent_TextBoxPersonName"); PersonsInCompany.GetPersonByFirstName(val.value, FinishCallback); } function FinishCallback(result) { document.getElementById("MainContent_LabelFirstName").innerHTML = result.FirstName; document.getElementById("MainContent_LabelName").innerHTML = result.Name; document.getElementById("MainContent_LabelAge").innerHTML = result.Age; document.getElementById("MainContent_LabelCompany").innerHTML = result.Company; } </script> Add some javascript, where you first call your webservice. Classname.Webmethod = PersonsInCompany.GetPersonByFirstName Add a callback to catch the result from the webservice. And use the result to update your page. <script type="text/javascript"> function GetPersonInCompany() { var val = document.getElementById("MainContent_TextBoxPersonName"); PersonsInCompany.GetPersonByFirstName(val.value, FinishCallback); } function FinishCallback(result) { document.getElementById("MainContent_LabelFirstName").innerHTML = result.FirstName; document.getElementById("MainContent_LabelName").innerHTML = result.Name; document.getElementById("MainContent_LabelAge").innerHTML = result.Age; document.getElementById("MainContent_LabelCompany").innerHTML = result.Company; } </script>   If you have any question, feel free to contact me! You can download the code here.

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  • Chrome opens to untitled blank page

    - by jackncoke
    I am working on a computer that had a lot of malware on it. I removed most of it to my knowledge. Now when I open Google Chrome I get a blank untitled page, with the traditional sign-in URL on top. If I go to the settings, the settings tab opens up blank as well. All pages that I navigate to will come up blank as well. The browser doesn't even perform a postback, it is like it is unresponsive. I did some googling and have seen people with similar errors, but no fixes. IE 8 works great without issues. Re-installing Chrome was the first thing I did! Any suggestions?

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  • Getting values from Dynamic elements.

    - by nCdy
    I'm adding some dynamic elements to my WebApp this way : (Language used is Nemerele (It has a simple C#-like syntax)) unless (GridView1.Rows.Count==0) { foreach(index with row = GridView1.Rows[index] in [0..GridView1.Rows.Count-1]) { row.Cells[0].Controls.Add ({ def TB = TextBox(); TB.EnableViewState = false; unless(row.Cells[0].Text == "&nbsp;") { TB.Text = row.Cells[0].Text; row.Cells[0].Text = ""; } TB.ID=TB.ClientID; TB.Width = 60; TB }); row.Cells[0].Controls.Add ({ def B = Button(); B.EnableViewState = false; B.Width = 80; B.Text = "?????????"; B.UseSubmitBehavior=false; // Makes no sense //B.OnClientClick="select(5);"; // HERE I CAN KNOW ABOUT TB.ID //B.Click+=EventHandler(fun(_,_) : void { }); // POST BACK KILL THAT ALL B }); } } This textboxes must make first field of GridView editable so ... but now I need to save a values. I can't do it on server side because any postback will Destroy all dynamic elements so I must do it without Post Back. So I try ... <script type="text/javascript" src="Scripts/jquery-1.4.1.min.js"></script> <script type="text/javascript"> function CallPageMethod(methodName, onSuccess, onFail) { var args = ''; var l = arguments.length; if (l > 3) { for (var i = 3; i < l - 1; i += 2) { if (args.length != 0) args += ','; args += '"' + arguments[i] + '":"' + arguments[i + 1] + '"'; } } var loc = window.location.href; loc = (loc.substr(loc.length - 1, 1) == "/") ? loc + "Report.aspx" : loc; $.ajax({ type: "POST", url: loc + "/" + methodName, data: "{" + args + "}", contentType: "application/json; charset=utf-8", dataType: "json", success: onSuccess, fail: onFail }); } function select(index) { var id = $("#id" + index).html(); CallPageMethod("SelectBook", success, fail, "id",id); } function success(response) { alert(response.d); } function fail(response) { alert("&#1054;&#1096;&#1080;&#1073;&#1082;&#1072;."); } </script> So... here is a trouble string : var id = $("#id" + index).html(); I know what is ID here : TB.ID=TB.ClientID; (when I add it) but I have no idea how to send it on Web Form. If I can add something like this div : <div id="Result" onclick="select(<%= " TB.ID " %>);"> Click here. </div> from the code it will be really goal, but I can't add this element as from CodeBehind as a dynamic element. So how can I transfer TB.ID or TB.ClientID to some static div Or how can I add some clickable dynamic element without PostBack to not destroy all my dynamic elements. Thank you.

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  • Top 50 ASP.Net Interview Questions & Answers

    - by Samir R. Bhogayta
    1. What is ASP.Net? It is a framework developed by Microsoft on which we can develop new generation web sites using web forms(aspx), MVC, HTML, Javascript, CSS etc. Its successor of Microsoft Active Server Pages(ASP). Currently there is ASP.NET 4.0, which is used to develop web sites. There are various page extensions provided by Microsoft that are being used for web site development. Eg: aspx, asmx, ascx, ashx, cs, vb, html, xml etc. 2. What’s the use of Response.Output.Write()? We can write formatted output  using Response.Output.Write(). 3. In which event of page cycle is the ViewState available?   After the Init() and before the Page_Load(). 4. What is the difference between Server.Transfer and Response.Redirect?   In Server.Transfer page processing transfers from one page to the other page without making a round-trip back to the client’s browser.  This provides a faster response with a little less overhead on the server.  The clients url history list or current url Server does not update in case of Server.Transfer. Response.Redirect is used to redirect the user’s browser to another page or site.  It performs trip back to the client where the client’s browser is redirected to the new page.  The user’s browser history list is updated to reflect the new address. 5. From which base class all Web Forms are inherited? Page class.  6. What are the different validators in ASP.NET? Required field Validator Range  Validator Compare Validator Custom Validator Regular expression Validator Summary Validator 7. Which validator control you use if you need to make sure the values in two different controls matched? Compare Validator control. 8. What is ViewState? ViewState is used to retain the state of server-side objects between page post backs. 9. Where the viewstate is stored after the page postback? ViewState is stored in a hidden field on the page at client side.  ViewState is transported to the client and back to the server, and is not stored on the server or any other external source. 10. How long the items in ViewState exists? They exist for the life of the current page. 11. What are the different Session state management options available in ASP.NET? In-Process Out-of-Process. In-Process stores the session in memory on the web server. Out-of-Process Session state management stores data in an external server.  The external server may be either a SQL Server or a State Server.  All objects stored in session are required to be serializable for Out-of-Process state management. 12. How you can add an event handler?  Using the Attributes property of server side control. e.g. [csharp] btnSubmit.Attributes.Add(“onMouseOver”,”JavascriptCode();”) [/csharp] 13. What is caching? Caching is a technique used to increase performance by keeping frequently accessed data or files in memory. The request for a cached file/data will be accessed from cache instead of actual location of that file. 14. What are the different types of caching? ASP.NET has 3 kinds of caching : Output Caching, Fragment Caching, Data Caching. 15. Which type if caching will be used if we want to cache the portion of a page instead of whole page? Fragment Caching: It caches the portion of the page generated by the request. For that, we can create user controls with the below code: [xml] <%@ OutputCache Duration=”120? VaryByParam=”CategoryID;SelectedID”%> [/xml] 16. List the events in page life cycle.   1) Page_PreInit 2) Page_Init 3) Page_InitComplete 4) Page_PreLoad 5) Page_Load 6) Page_LoadComplete 7) Page_PreRender 8)Render 17. Can we have a web application running without web.Config file?   Yes 18. Is it possible to create web application with both webforms and mvc? Yes. We have to include below mvc assembly references in the web forms application to create hybrid application. [csharp] System.Web.Mvc System.Web.Razor System.ComponentModel.DataAnnotations [/csharp] 19. Can we add code files of different languages in App_Code folder?   No. The code files must be in same language to be kept in App_code folder. 20. What is Protected Configuration? It is a feature used to secure connection string information. 21. Write code to send e-mail from an ASP.NET application? [csharp] MailMessage mailMess = new MailMessage (); mailMess.From = “[email protected]”; mailMess.To = “[email protected]”; mailMess.Subject = “Test email”; mailMess.Body = “Hi This is a test mail.”; SmtpMail.SmtpServer = “localhost”; SmtpMail.Send (mailMess); [/csharp] MailMessage and SmtpMail are classes defined System.Web.Mail namespace.  22. How can we prevent browser from caching an ASPX page?   We can SetNoStore on HttpCachePolicy object exposed by the Response object’s Cache property: [csharp] Response.Cache.SetNoStore (); Response.Write (DateTime.Now.ToLongTimeString ()); [/csharp] 23. What is the good practice to implement validations in aspx page? Client-side validation is the best way to validate data of a web page. It reduces the network traffic and saves server resources. 24. What are the event handlers that we can have in Global.asax file? Application Events: Application_Start , Application_End, Application_AcquireRequestState, Application_AuthenticateRequest, Application_AuthorizeRequest, Application_BeginRequest, Application_Disposed,  Application_EndRequest, Application_Error, Application_PostRequestHandlerExecute, Application_PreRequestHandlerExecute, Application_PreSendRequestContent, Application_PreSendRequestHeaders, Application_ReleaseRequestState, Application_ResolveRequestCache, Application_UpdateRequestCache Session Events: Session_Start,Session_End 25. Which protocol is used to call a Web service? HTTP Protocol 26. Can we have multiple web config files for an asp.net application? Yes. 27. What is the difference between web config and machine config? Web config file is specific to a web application where as machine config is specific to a machine or server. There can be multiple web config files into an application where as we can have only one machine config file on a server. 28.  Explain role based security ?   Role Based Security used to implement security based on roles assigned to user groups in the organization. Then we can allow or deny users based on their role in the organization. Windows defines several built-in groups, including Administrators, Users, and Guests. [xml] <AUTHORIZATION>< authorization > < allow roles=”Domain_Name\Administrators” / >   < !– Allow Administrators in domain. — > < deny users=”*”  / >                            < !– Deny anyone else. — > < /authorization > [/xml] 29. What is Cross Page Posting? When we click submit button on a web page, the page post the data to the same page. The technique in which we post the data to different pages is called Cross Page posting. This can be achieved by setting POSTBACKURL property of  the button that causes the postback. Findcontrol method of PreviousPage can be used to get the posted values on the page to which the page has been posted. 30. How can we apply Themes to an asp.net application? We can specify the theme in web.config file. Below is the code example to apply theme: [xml] <configuration> <system.web> <pages theme=”Windows7? /> </system.web> </configuration> [/xml] 31: What is RedirectPermanent in ASP.Net?   RedirectPermanent Performs a permanent redirection from the requested URL to the specified URL. Once the redirection is done, it also returns 301 Moved Permanently responses. 32: What is MVC? MVC is a framework used to create web applications. The web application base builds on  Model-View-Controller pattern which separates the application logic from UI, and the input and events from the user will be controlled by the Controller. 33. Explain the working of passport authentication. First of all it checks passport authentication cookie. If the cookie is not available then the application redirects the user to Passport Sign on page. Passport service authenticates the user details on sign on page and if valid then stores the authenticated cookie on client machine and then redirect the user to requested page 34. What are the advantages of Passport authentication? All the websites can be accessed using single login credentials. So no need to remember login credentials for each web site. Users can maintain his/ her information in a single location. 35. What are the asp.net Security Controls? <asp:Login>: Provides a standard login capability that allows the users to enter their credentials <asp:LoginName>: Allows you to display the name of the logged-in user <asp:LoginStatus>: Displays whether the user is authenticated or not <asp:LoginView>: Provides various login views depending on the selected template <asp:PasswordRecovery>:  email the users their lost password 36: How do you register JavaScript for webcontrols ? We can register javascript for controls using <CONTROL -name>Attribtues.Add(scriptname,scripttext) method. 37. In which event are the controls fully loaded? Page load event. 38: what is boxing and unboxing? Boxing is assigning a value type to reference type variable. Unboxing is reverse of boxing ie. Assigning reference type variable to value type variable. 39. Differentiate strong typing and weak typing In strong typing, the data types of variable are checked at compile time. On the other hand, in case of weak typing the variable data types are checked at runtime. In case of strong typing, there is no chance of compilation error. Scripts use weak typing and hence issues arises at runtime. 40. How we can force all the validation controls to run? The Page.Validate() method is used to force all the validation controls to run and to perform validation. 41. List all templates of the Repeater control. ItemTemplate AlternatingltemTemplate SeparatorTemplate HeaderTemplate FooterTemplate 42. List the major built-in objects in ASP.NET?  Application Request Response Server Session Context Trace 43. What is the appSettings Section in the web.config file? The appSettings block in web config file sets the user-defined values for the whole application. For example, in the following code snippet, the specified ConnectionString section is used throughout the project for database connection: [csharp] <em><configuration> <appSettings> <add key=”ConnectionString” value=”server=local; pwd=password; database=default” /> </appSettings></em> [/csharp] 44.      Which data type does the RangeValidator control support? The data types supported by the RangeValidator control are Integer, Double, String, Currency, and Date. 45. What is the difference between an HtmlInputCheckBox control and anHtmlInputRadioButton control? In HtmlInputCheckBoxcontrol, multiple item selection is possible whereas in HtmlInputRadioButton controls, we can select only single item from the group of items. 46. Which namespaces are necessary to create a localized application? System.Globalization System.Resources 47. What are the different types of cookies in ASP.NET? Session Cookie – Resides on the client machine for a single session until the user does not log out. Persistent Cookie – Resides on a user’s machine for a period specified for its expiry, such as 10 days, one month, and never. 48. What is the file extension of web service? Web services have file extension .asmx.. 49. What are the components of ADO.NET? The components of ADO.Net are Dataset, Data Reader, Data Adaptor, Command, connection. 50. What is the difference between ExecuteScalar and ExecuteNonQuery? ExecuteScalar returns output value where as ExecuteNonQuery does not return any value but the number of rows affected by the query. ExecuteScalar used for fetching a single value and ExecuteNonQuery used to execute Insert and Update statements.

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  • Telerik RadWindow does not fire ClientCallBackFunction after a ajax an __DoPostBack

    - by Richard
    HI, I have a Telerik radwindow that allows our users to upload files. When the user first opens the radwindow and sees the upload fields, they can happily select a file and upload it. The window then returns the id of the uploaded file back to the parent page via the ClientCallBackFunction. This function then passes in the ID to a javascript function that calls __DoPostback so that we can populate the list of uploaded files. First time around it works a treat. However all subsequent times it fails to call ClientCallBackFunction unless i refresh the entire page. I also note that any other control on the parent page to uses an ajax postback also stops the ClientCallBackFunction begin called, even on the first time. any ideas? Thanks Richard

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  • SetPartialRenderingMode can only be called once?

    - by lucian.jp
    I have a asp.net web form full of ajax. Every time a postback is made, the server event execute correctly, but when the page is rendering I get this error : Error : Sys.WebForms.PageRequestManagerServerErrorException: SetPartialRenderingMode can only be called once. A search with SetPartialRenderingMode on google was unsuccessful. It seems it is related to AjaxControlToolkit. I have created a simple demo project that reproduce the problem. You can find it here (VS 2008 .NET 3.5). Note that you only see the error in IE7, it doesn't work in FF either but no error appear.

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  • AJAX TabContainer containing user controls

    - by Ali
    Hi all, Wondering if someone here can help. I have an AJAX tabcontainer which has a number of tabs and each tab contains a user control. When I add a new item from one of the tabs, it is not reflected in the user control in another tab unless a postback occurs. (e.g. the first tab has a listview where I add a new record and the second has a simple form which contains a drop-down which I expect to contain value added from first tab). How can I make the tabcontainer to refresh its tabs from a usercontrol? Any help will be most appreciated. Thanks, Ali

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  • Adding custom options in binded dropdown in asp.net

    - by MarceloRamires
    I have a bound dropdown list populated with a table of names through a select, and databinding. it shoots selectedindexchanged that (through a postback) updates a certain gridview. What happens is, since it runs from changing the index, the one that always comes selected (alexander) can only me chosen if you choose another one, then choose alexander. poor alexander. What I want is to put a blanc option at the beginning (default) and (if possible) a option as second. I can't add this option manually, since the binding wipes whatever was in the dropdown list and puts the content of the datasource.

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  • ASP.NET MVC DropDownList Validation

    - by Andrew Florko
    Hello everybody, I have [DisplayName("Country")] public List<SelectListItem> Countries { get; set; } property in Model class for DropDownList. When I try to check if the ModelState.IsValid on form postback it's always false & error for Countries tells "Can't convert [value] to SelectListItem" or some of a kind. I figured out there is no straight-forward mapping for drop down selected value (looks like I'll have to read value from Form value collection), but how can I ignore binding and validation for List property? I just want to make ModelState.IsValid attribute to be true if all the other fields are populated properly. Thank you in advance

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  • $.Ajax send with progress bar using jquery

    - by kamiar3001
    Hi folks I use $.ajax functionality to send data to server and with this method I removed most of postback pages it works but I need some progress bar to show visitors there are some progress now it shows nothing after some second it shows result but i think a message or small picture is need in my web site. How I can implement it with simple jquery code ? something popup and shows the page is in the progress. And also I need to add some other jquery to prevent other click during the progress is it possible ?

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  • How do I Reset the Values in My ASP.NET Fields?

    - by Giffyguy
    The current form is here. It is not complete, and only a couple options will work. Select "Image CD" and then any resolution and click "Add to Order." The order will be recorded on the server-side, but on the client-side I need to reset the product drop-down to "{select}" so that the user will know that they need to select another product. This is consistant with the idea that the sub-selections disappear. I don't know whether I should be using ASP postback or standard form submittal, and most of the fields need to be reset when the user adds an item to the order.

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