Class cannot find another class in the same namespace

Question

I have a C# WebApp that we are doing for a client. I have two classes in the project, defined (in separate files) as such...

A general utility library:

namespace Client.WebApp {
    public static class General {
        public static MyDbClass GetDB() {
            //<creates and returns MyDbClass here>
        }
    }
}

A PageBase class:

namespace Client.WebApp {
    public class PageBase : System.Web.UI.Page {
        protected MyDbClass dbo { get; set; }

        public PageBase() {
            dbo = General.GetDB();
        }
    }
}

When I try to compile, I get the error from the dbo = General.GetDB(); line:
The name 'General' does not exist in the current context Client.WebApp.

• I have double-checked that the namespace is spelled right in both files.
• I have tried adding the top-level namespace Client.WebApp as a using directive in the pagebase file.
• I have tried fully qualifying the name as in dbo = Client.WebApp.General.GetDB();

Nothing has helped and it insists that my General class does not exist. Funny thing is that while the build hits this error and stops, the code-editor does not see this error, and the statement does not get red-under-squiggled.

The project is targeting Framework v.4.5.2, and I am working in VS 2015.

Solution 1

It is a strange error, in my VS2015 if I set a file Build Action to anything other than "Compile", I get an error underline on any type for that file.

Anyway the solution here is to verify that the Build Action is set to "Compile", I'm not sure why adding a new file would have set the build action to anything other than "Compile". I've also tested trying to add new files in multiple ways (select a text file template and just name it something.cs), it still sets it as "Compile". You should verify that your VS2015 instance is updated with the latest updates.

Solution 2

I had the same problem: "type or namespace could not be found". It turned out that class was in a file with the "Build Action" property set to "None", meaning the file was not being compiled. I set it to "C# Compiler", that solved it.

Comments

[DWright]

Man, you just helped me figure out something that was driving me crazy! For some reason one file had gotten set to Build Action = Content, not Compile. Super non-obvious. Finding your answer made me check.

[ecnepsnai]

If the file is set to "Compile" you might just have to restart visual studio entirly. This bug seems to have stuck around with VS2017

[Bryan Harrington]

Confirmed, closing VS17 down, reopening, Clean, Rebuild seems to solve it.

[Jeff Blumenthal]

As ecnepsnai said... Restart fixed it. Thx