Question

I have a POCO object and I want to mark a property as a key (see TestClass below).
I’m getting the following error.

‘Key’ cannot be used as an attribute because it is not a class. C:\Users\zzz\Documents\Visual Studio 2010\Projects\zzz\zzz\BO\TestClass.vb

Public Class TestClass

  <Key()>
  Private _TestIdentifier As String
  Public Property TestIdentifier() As String
    Get
        Return _TestIdentifier
    End Get
    Set(ByVal value As String)
      _TestIdentifier = value
      '  Me.NotifyPropertyChanged("TestIdentifier")
    End Set
  End Property

End Class

Answer 1

I had a missing import and reference
Imports System.ComponentModel.DataAnnotations
And reference System.ComponentModel.DataAnnotations.dll