Confusion about Namespaces and App_Code, etc. in VS2008/ASP.net3.5


Alex Maghen

I'm not sure whether this is about Visual Studio 2008 or ASP.NET 3.5 but
something has changed that I just don't understand:

It used to be that when I created a class and placed it in the special
App_Code directory, I could wrap it in any namespace I liked and then use the
"using" directive in my .aspx pages for that Namespace and I'd have access to
the class.

Now, when I create a class, it is automatically given a crazy namespace that
is something like <projname>.<foldername>. And yet, if I reference that
namespace from .aspx.cs pages, I still cannot access the class.

What has changed here?




Allen Chen [MSFT]

Hi Alex,

From your description I think you're using Web Application instead of Web
Site project. Please try to create a Web Site project to test if the
problem still occurs.

In a Web Application project the App_Code folder is just like a normal
folder. The classes in the Web Application project is intended to be
compiled to an assembly at compile time instead of being automatically
compiled at run time. The problem you met with is due to that the IDE
doesn't know the file in the App_Code folder need to be compiled. To add
class file in App_Code folder (or any other folder you like) I recommend
you right click the project name to add a new item instead of right
clicking the App_Code folder icon. After that, drag the class file to the
App_Code folder. In this way the IDE will compile the class file.

If you right click the App_Code folder to create the class file you can
notify the IDE in this way:

1. Find the class file in the App_Code folder. Select it.

2. In the properties window change the Build Action from "Content" to

3. Now try to access the class in your aspx.cs. It should work.

Or manually edit the *.csproj file:

1. Open the *.csproj file of the current project with Notepad.

2. Find this item in it (assume you've created the Class4.cs in the
App_Code folder by right clicking the folder icon in the solution explorer
window to add new item):

<Content Include="App_Code\Class4.cs" />

3. Replace it with:
<Compile Include="App_Code\Class4.cs" />

4. Save the file.
5. Back to Visual Studio, click "Reload" when you see a popup window.
6. Now try to access the Class4 in your aspx.cs. It should work.

Please have a try and feel free to ask if you have further questions.

Allen Chen
Microsoft Online Community Support

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Allen Chen [MSFT]

Hi Alex,

Have you got the expected answer? Please feel free to ask if you have
further questions.

Allen Chen
Microsoft Online Support

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