Error with GUI HTML designer using a custom base code-behind class

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fm@newsgroups.nospam - 04 Aug 2004 00:13 GMT

I was working on converting an example pattern from C# to VB.NET for Page Controller in http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnpatterns/html
/EspServicesPatterns.asp (Web Service Patterns) when I ran into a nasty bug. I have not tried just setting up a project with their C# to see if it works. We are a VB shop and I'd like to make a case for using this pattern. But not if there is some weird sequence to get it to work.

1) I create a web app project.

2) I add a vb class file with this code:
Imports System
Imports System.Web.UI
Imports System.Web.UI.WebControls

Public Class BasePage
Inherits System.Web.UI.Page

End Class

3) I build the solution.

4) I go to the code behind page of WebForm1.aspx and change the Inherited class from System.Web.UI.Page to BasePage

5) I switch over to the designer page and I receive the following error:
The designer could not be shown for this file because none of the classes within it can be designed. The designer inspected the following classes in the file:

WebForm1 --- The base class 'PageController.BasePage' could not be loaded. Ensure the assembly has been referenced or built if it is part of the project.

Thanks!

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Jakob Christensen - 04 Aug 2004 07:49 GMT

Try building your project and afterwards it will work just fine. Naturally, the design view does not work for a base class that does not yet exist. A better solution would be to put BaseClass in another assemly and then reference this assembly.

Regards, Jakob.

> I was working on converting an example pattern from C# to VB.NET for Page Controller in http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnpatterns/html
/EspServicesPatterns.asp (Web Service Patterns) when I ran into a nasty bug. I have not tried just setting up a project with their C# to see if it works. We are a VB shop and I'd like to make a case for using this pattern. But not if there is some weird sequence to get it to work.
>
[quoted text clipped - 20 lines]
>
> Thanks!

Reply to this Message

Steven Cheng[MSFT] - 04 Aug 2004 08:08 GMT

Hi,

As for the error you encountered when trying view a webpage indesignvidw
which is derived from a custom base page class(inherit System.Web.UI.Page),
I think Jakob's suggestion is reasonable. And I've also done a test on
myside. Are you put the custom base page class's source file(class.vb)
together with the other pages and codebehinds in the web project? If so,
you need to build the web project first so as to make the base page class
existing in the web project's main assembly. If not, since the VS.NET can't
find the class in the existing asemlies so when try lanuch an instance of
the base class when we swtich into design-view you'll get the error.
In addition, you can also try create another class library project to
centralize all the base classes and build them into assembly separatly and
finally reference them by adding the assembly as reference in the web
project.

Thanks.

Regards,

Steven Cheng
Microsoft Online Support

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Error with GUI HTML designer using a custom base code-behind class

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