Home

Castle Stronghold

•  
• Home
• Download
• API Doc
• Using
• Forum
• Jira/Issue tracker
• Builds

WebForms View Engine

With WebForms you can use all your existing skills to develop MonoRail applications, however its integration with MonoRail can be quite tricky. The reason for this is that in MonoRail (or any other MVC framework) the controller should be the first entity invoked. For WebForms, the page is everything (the controller, the view and sometimes the model).

Let's take a look at an example of perfectly decent controller code and explain when it does not integrate with WebForms.

public class AccountController : SmartDispatcherController
{
  public void Index()
  {
    // empty, just render the index.aspx view so the user 
    // can fill the form
  }

  public void Save(String name, String email)
  {
    if (name.Length == 0 || email.Length == 0)
    {
      Flash["error"] = "Please, fill both Name and Email";
      RenderView("index");
      return;
    }

    AccountServices.Create(name, email);

    RenderView("success");
  }
}

And here is the source code of the page:

<form runat="server">
  Name: <asp:TextBox ID="name" Runat="server" />
  Email: <asp:TextBox ID="email" Runat="server" />
  <asp:Button ID="Save" Text="Save" Runat="server" />
</form>

When the Webform is rendered, the form action will point to the original url, which is account/index.rails. But we want to execute the Save action instead... what to do?

Well, one approach is to handle the Save click on the server side:

<form runat="server">
  <asp:Button ID="Save" Text="Save" Runat="server" OnClick="OnSave" />
</form>

In the WebForm code, you can implement the IControllerAware interface so you have access to the controller instance. This means that in the OnSave event handler, we can delegate the execution back to the controller:

public class Index : System.Web.UI.Page, IControllerAware
{
    private Controller _controller;

    public void SetController(Controller controller)
    {
        _controller = controller;
    }

    public void OnSave(object sender, EventArgs args)
    {
        _controller.Send("Save");
    }
}

While this works, if the Save action is completed successfully it will send back the success.aspx page. The problem here is that WebForm will try to populate the controls tree with the view state on the request, which will fail.

''What if we just change the form action through javascript'' you might inquire. Well, the same view state problem will happen. However, we can substitute the RenderView with Redirect and then everything works. But of course, there's a cost involved.

In this same sample, if the Save action decided that there was missing data and used RenderView("index") then you're in big trouble. That's because Index.aspx will be reprocessed, which it will interpret as a post back and so will invoke the button event handler again, which will delegate to the controller again, and so on.

So, many simple scenarios can get really hard with WebForms.

Layouts

To use MonoRail layouts with the WebForms View engine, you must create an ordinary aspx file on the layouts folder. You must use MasterPageBase as the base class, otherwise you will have a view state name clash.

The following is an example of a layout:

<%@ Page Inherits="Castle.MonoRail.Framework.Views.Aspx.MasterPageBase" %>
<%@ Register tagprefix="rails" namespace="Castle.MonoRail.Framework.Views.Aspx" assembly="Castle.MonoRail.Framework" %>
Different master page
<p><rails:Contents id="contents" runat="server" /></p>
Footer

The control Contents outputs the the view content.

Content

Search WWW Search castleproject.org