Retrieving Custom Attributes on Enumeration Members

Dominick Marciano

I designed a custom attribute using the following class:

_
Public Class OutputDescriptionAttribute
Inherits Attribute

#Region "Variables"
Private _oldDescription As String
Private _newDescription As String
#End Region

#Region "Properties"
Public ReadOnly Property OldDescription As String
Get
Return Me._oldDescription
End Get
End Property

Public ReadOnly Property NewDescription As String
    Get
        Return Me.\_newDescription
    End Get
End Property

#End Region

#Region "Constructor"
Public Sub New(oldDescription As String, newDescription As String)
Me._oldDescription = oldDescription
Me._newDescription = newDescription
End Sub
#End Region

End Class

And I apply the attribute to various enumerations. For example:

Public Enum ConditionType
Intact
Fair
Poor
None
End Enum

What I haven't be able to figure out exactly, is how to get one of the attribute's properties for a specific enumeration member. For example, if I have a variable Dim condition As ConditionType = ConditionType.Fair and I want to retrieve either the NewDescription or OldDescription property of the attribute tag ("Fair" or "F" respectively) how can I go about doing this. Currently I was using the following function to test out methods:

Private Sub GetAttribute(T As Type)

     Dim attr As OutputDescriptionAttribute = CType(Attribute.GetCustomAttribute(T, GetType(OutputDescriptionAttribute)), OutputDescriptionAttribute)

    Dim newDesc As String = attr.NewDescription
    Dim oldDesc As String = attr.OldDescription

End Sub

If I call this method using GetAttribute(GetType(ConditionType)) I get no error message, however if I try doing the following:

Dim condition As ConditionType = ConditionType.Fair
GetAttribute(condition.GetType)

I get any error about ConditionType cannot be converted to a needed type. How can I go about getting the custom attribute that is applied to a specific enumeration member? Thanks in advance.

Lost User

I've taken your class and put it in a console-application; below is the code that fetches the member, and then the attributes of said member.

Sub Main()
Dim someCondition As ConditionType = ConditionType.Fair
Dim mi As MemberInfo = GetType(ConditionType).GetMember(someCondition.ToString()).FirstOrDefault()
Dim attribute As OutputDescriptionAttribute = mi.GetCustomAttributes(GetType(OutputDescriptionAttribute)).FirstOrDefault()
Console.WriteLine(attribute.NewDescription)
Console.ReadLine()
End Sub

You might want to put this into a nice little helper-method. Generics and method extensions would help in keeping above code readable.

Bastard Programmer from Hell :suss: If you can't read my code, try converting it here[^]