I am guessing a lot of people out there are like me and have projects that they started working on in ASP.Net 1.1, and later migrated to 2.0. This blog is about how to move your old files into the brave new world...

One of the neat features with web forms created from scratch in 2.0 is the separation of the Code Behind files into two partial classes: one partial class in a file called formname.aspx.designer.cs, and one in formname.aspx.cs. The designer file is autogenerated and contains declarations of all the form level variables, for instance if you drop a TextBox tbMyTextBox onto your form, it will add a line

System.Web.UI.WebControls.TextBox tbMyTextBox

to your designer file.

The other Code Behind file is the one where you write your code, event handlers, etc. The two partial class files are then combined at compile time into one class.

So, how do I take an old 1.1 Code Behind file and separate it into the two files I would have had if I had created it in 2.0? Well, follow these steps:

1. Go to the aspx (same applies for asxc files) file, and change the Page directive to say CodeFile="formname.aspx.cs" instead of Codebehind="formname.aspx.cs"

2. Go to your Code Behind file and delete all the member control declarations that should be in the designer file, for instance the tbMyTextBox in my example (be careful not to delete any other private member variables you may have interspersed with the generated code).

3. Still in the old Code Behind file, add partial in front of the class name of the form, for instance

public partial class formname : System.Web.UI.Page

These three steps are sometimes enough for the IDE to kick in and generate your Code Behind file, but if not, you can prod it on its way a little:

4. Create a file called formname.aspx.designer.cs in the same directory as your formnam.aspx.cs, and copy the basic partial class skeleton structure from your code behind (dont include the : System.Web.UI.Page, and use the same namespace as your partial class):

namespace YourNameSpace {

public partial class formname {

   }
}

5. Add this new file to the project (Project, Add Existing Item). It should line up nicely with your Code Behind file under the aspx node in the Solution Explorer.

6. Go back to the aspx file and change the ID of some arbitrary form level control, then hit Save.... change it back and save again. Now look at your empty stub of a partial class again from step 4...TADA! It now contains declarations for all of your form controls (not just the one you changed!).

By the way, if you for some reason want to declare a member control differently from the way the designer autogenerates it, you can just move it from the generated file back into your file and change for instance the visibility of the variable. The generator checks for existing declarations before it adds them to the generated file (hence step 2 above).

I know this is a tad tedious, I wish there was a wizard, but at least you now know how to make the conversion manually.