ASP.net RequiredFieldValidator not preventing postback

asp.netvalidation

I have a question about what could stop a RequiredFieldValidator from preventing a postback.

I began working on an older, but simple aspx form and my predecessor used manual, server-side form validation (checking to see if some form fields have a value and if not displaying an error message in a label). I thought I'd clean out some unneeded code and replace the manual checking with RequiredFieldValidator controls, but while they appear to be validating, they aren't preventing a postback. Ie., I get my error messages displayed but the postback still occurs.

The form is quite simple and there are no CausesValidation="false" attributes set. My controls look like:

 <asp:TextBox ID="txtPhone" Runat="server" Columns="20" MaxLength="20" />
 <asp:RequiredFieldValidator ID="rfvPhone" runat="server" Display="Dynamic"
      ErrorMessage="* Required" ControlToValidate="txtPhone" />

I created a brand new webform in the same project with just a single textbox, validator and submit button and it acts the same way. Error message displays but postback still occurs.

Is there a global or project-wide setting that would cause this behaviour? Something in the web.config or global.asax?

Best Answer

Whew. Okay, I found the problem, basically by creating a brand new project and comparing its web.config line-by-line with my old project. Turns out the culprit is this:

 <xhtmlConformance mode="Legacy"/>

If I remove the line, my validation works the way I expected it to. Googling that uncovered a bunch of blog posts about how VisualStudio adds that line to the web.config when upgrading web apps from .net 1.1 to .net 3.5.

The blog posts were mainly complaining about how that field interferes with .net's AJAX stuff, but I'm guessing it messes with the JavaScript emitted for the RequiredFieldValidator in a similar fashion.

Website:

The Web Site project is compiled on the fly. You end up with a lot more DLL files, which can be a pain. It also gives problems when you have pages or controls in one directory that need to reference pages and controls in another directory since the other directory may not be compiled into the code yet. Another problem can be in publishing.

If Visual Studio isn't told to re-use the same names constantly, it will come up with new names for the DLL files generated by pages all the time. That can lead to having several close copies of DLL files containing the same class name, which will generate plenty of errors. The Web Site project was introduced with Visual Studio 2005, but it has turned out not to be popular.

Web Application:

The Web Application Project was created as an add-in and now exists as part of SP 1 for Visual Studio 2005. The main differences are the Web Application Project was designed to work similarly to the Web projects that shipped with Visual Studio 2003. It will compile the application into a single DLL file at build time. To update the project, it must be recompiled and the DLL file published for changes to occur.

Another nice feature of the Web Application project is it's much easier to exclude files from the project view. In the Web Site project, each file that you exclude is renamed with an excluded keyword in the filename. In the Web Application Project, the project just keeps track of which files to include/exclude from the project view without renaming them, making things much tidier.

Reference

The article ASP.NET 2.0 - Web Site vs Web Application project also gives reasons on why to use one and not the other. Here is an excerpt of it:

You need to migrate large Visual Studio .NET 2003 applications to VS 2005? use the Web Application project.

You want to open and edit any directory as a Web project without creating a project file? use Web Site project.

You need to add pre-build and post-build steps during compilation? use Web Application project.

You need to build a Web application using multiple Web projects? use the Web Application project.

You want to generate one assembly for each page? use the Web Site project.

You prefer dynamic compilation and working on pages without building entire site on each page view? use Web Site project.

You prefer single-page code model to code-behind model? use Web Site project.

Web Application Projects versus Web Site Projects (MSDN) explains the differences between the web site and web application projects. Also, it discusses the configuration to be made in Visual Studio.

Controls not retaining values after postback when FormView set to insert mode

This answer from other forum by Walter Wang [MSFT] - 26 Jan 2007 03:29 GMT

First, the problem appears to be that the FormView is told by the data source control that the data has changed, and therefore it should rebind to get the new data. This actually should not have been done since we're still in Insert mode. I have got a workaround for your reference: Inherit from FormView to create your own FormView control, override OnDataSourceViewChanged and set RequiresDataBinding to false if we're in Insert mode:
public class MyFormView : FormView
   {
       protected override void OnDataSourceViewChanged(object sender,
EventArgs e)
       {
           if (this.CurrentMode == FormViewMode.Insert)
           {
               this.RequiresDataBinding = false;
           }
           else
           {
               base.OnDataSourceViewChanged(sender, e);
           }
       }
   }

I've tested it on my side and it seems working correctly. Please give it a try and let me know the result.

Best Answer

Related Solutions

.net – ASP.NET Web Site or ASP.NET Web Application

Website:

Web Application:

Controls not retaining values after postback when FormView set to insert mode

Related Topic