Custom Nullable Class

[Guest]

I developed a custom file attachments class for an application and from the
UI the user can choose to upload attachments. There is a add method that
takes a FileAttachmentCollection object, runs a for each, and uploads each
attachment. I was thinking that it would be nice to allow it to be Nullable
if they happen not choose to upload attachments when submitting data. When I
try Public Sub Add(attachments As Nullable(Of FileAttachmentCollection) I
get: Type argument 'BusinessLogicLayer.FileAttachmentCollection' does not
satisfy the 'Structure' constraint for type parameter 'T'. I am doing the
following for my collection.

Public Class FileAttachmentCollection
Inherits System.Collections.ObjectModel.Collection(Of FileAttachment)
End Class

Any thoughts on how to correct this error?


Is there an easy way to fix this?

 

[Mattias Sjögren]

Nick,

Any thoughts on how to correct this error?


Is there an easy way to fix this?

Yes, just change the signature to

Public Sub Add(attachments As FileAttachmentCollection)

Since FileAttachmentCollection is a Class, it's already nullable.


Mattias