Visual studio cannot detect newly created class for asp.net "website"

Question

I am trying to modify an existing .net "website" project by adding a new class to it. I added my class inside the App_Code folder (let's call this class "ClassA"), and tried to access it from the outside in an aspx.cs file. For some reason, right after I created the class, I can create an instance of it in my aspx.cs file without any warnings from Visual Studio (e.g., ClassA a = new ClassA()). But every time I rebuild the project, I get the following Error from visual studio (The type or namespace name 'ClassA' could not be found (are you missing a using directive or an assembly reference?)). What am I missing here?

Code for Class A -> App_Code/ClassA.cs

public class ClassA
{
  public string test;
}

Code for Test.aspx.cs

namespace A{
  public class Test : System.Web.UI.Page
  {
    protected void Page_Load(object sender, EventArgs e)
    {
      ClassA a = new ClassA(); // line with error
    }
  }
}

If I put everything in Test.aspx.cs I get no errors:

namespace A{
  public class ClassA
  {
    public string test;
  }

  public class Test : System.Web.UI.Page
  {
    protected void Page_Load(object sender, EventArgs e)
    {
      ClassA a = new ClassA(); // no error!
    }
  }
}

Have you modified the namespace of the ClassA?, as by default it append the folder name(.App+Code) in Namespace. — Jha.prashant, Dec 19 '13 at 17:21
Is it a web *site* or a web *project*? A website is not really compiled in compile-time (no output DLL), while a web project is (a single output DLL). If it's a web project and you've got code in App_Code, it's going to result in you having the class there twice (once runtime compiled from App_Code, and once again in the compiled DLL). — Luaan, Dec 19 '13 at 17:24
Have you tried deleting your Temporary ASP.NET Files folder? I've had this happen to me a few times. A restart fixed the problem in those cases. There was an open file handle on the Temporary ASP.NET files, so the old DLL's were not being removed. — mwilson, Dec 19 '13 at 17:36
Please check this post, It will help you: [App_Code and App_Data][1] [1]: http://stackoverflow.com/questions/7480437/asp-net-app-data-app-code-folders — Jha.prashant, Dec 19 '13 at 17:40

score 7 · Accepted Answer · answered Dec 19 '13 at 17:48

7

By default the classes inside App_Code folder has property "Build Action" set as "Content".

If you want to use it you need to set its "Build Action" property to "Compile".

This should work.

answered Dec 19 '13 at 17:48

Jha.prashant

233
1
8

Hi, I'm not sure if this was the solution that solved the problem, but I tried a bunch of things suggested in this thread (this solution was the last thing I tried) and it works now. Thanks. – Discombobulous Dec 19 '13 at 17:51
Eric@nothing else was needed. Your namespace and code was good. – Jha.prashant Dec 19 '13 at 18:32

score 3 · Answer 2 · edited May 11 '14 at 17:00

3

I am really sorry, for I could not totally understand the problem. In my opinion you should not use namespaces when you create a class in app_code and let it be accessible to the whole website project.
In this instance you have added a namespace, try adding:

using b;

where b is your namespace you used in your new class. This should solve your problem.

edited May 11 '14 at 17:00

Simon Martin

4,203
7
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93

answered Dec 19 '13 at 17:27

Alok

1,290
1
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21

so I removed the namespace in the class definition file in App_code. I'm still getting the same error in my aspx.cs file outside of app_code (The type or namespace name 'ClassA' could not be found) – Discombobulous Dec 19 '13 at 17:32
@EricChen Please update your question with the current code you're using. – mason Dec 19 '13 at 17:35

Visual studio cannot detect newly created class for asp.net "website"

2 Answers2