Local C# Class Cannot be Added to Class Diagram

Question

_{Monday, September 19, 2016 1:19 PM | 1 vote}

Hi,

I'm using Visual Studio 2015 for an Umbraco CMS website.

I have a very simple public ViewModel class. 

I have created a class diagram file in the same folder of the project, but when I drag my VM class on it, an error message box says "one or more of the selected items cannot be added to the class diagram".

It's really strange, it's a local file, in the same folder, it's public, etc.

Can anyone please tell me what am I doing wrong?

Thanks,

Sia

All replies (2)

_{Tuesday, September 20, 2016 3:17 AM ✅Answered}

Hi maroonedsia2,

In my side, I could drag all classes to the class diagram without any problems from class view. Please refer to the following screenshot.

According to your description, does the VM class call other references? Please refer to the following steps to troubleshot this issue:

1). Please create a new project, and add a class diagram and some classes to it. To observe whether has the same issue, this method could help us exclude the reasons caused by Visual Studio.

2). Please create a new simple class to your project, and drag it to class diagram to observe whether has the same issue. Which could help us to judge whether this issue caused by VM class.

3). Please make sure all required assemblies from VM class are referenced.

Sincerely,

Oscar

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_{Thursday, December 19, 2019 6:16 PM}

Hello!

I just found I had the exact same problem in an existing VB.NET project, and I discovered that classes that had a

Namespace Global.HM.Events

    Public Class Event_mytest

        '  Class features here.

    End Class

End Namespace

would not display in the Class Diagram and would issue the above message ("One or more of the selected items cannot be added to the class diagram.") when I try to drag the class into the diagram.  This was true even though the project builds without any errors.

However, if I changed the Namespace to something without the "Global." in it, e.g.

    Namespace aaa

then it CAN be dragged and displayed in the class diagram.

And to be clear, THIS IS THE PROJECT that defines the class -- the source code is in this project.

The error persisted even when I went to Project > Properties > References and included HM.Events in the Imported Namespaces.

My company uses several Global.HM.xxxxx  name spaces in our software.  However, we are not making separate DLLs with them, or having those namespaces defined in a separate project, but including families of classes that work together in projects that all share such namespaces.  Other classes that use features in such class families simply do this:

    Imports HM.Events

So I have 3 questions:

1.  Is there a way to display classes defined in the local project that are within Global.HM.Events?

2.  Is there something wrong with using "Global.xxx.xxx" in defining company-wide namespaces for families of classes that work together?

3.  Or is this a bug in the Class Diagram that simply won't let you ADD a class that is in the "Global.subspace" namespace?

IMPORTANT NOTE:  If I change my test class namespaces to not have "Global." in them and THEN add them to the class diagram, and then put the "Global." back into the class, they remain correctly displayed in the diagram!  (It almost looks like this is a bug in the ADD A CLASS step in the Class Diagram tool...  Please correct me if I am wrong.)

Kind regards,

Vic

P.S.  I am using Visual Studio 2017 Community Edition, and just updated it, and just installed the Class Diagram component.