Question

I would like the following function to return Nothing if the element with the specified key is not in the collection. Instead, it returns an error – something to the effect of “no element found”

Public Class MyCollection

    Inherits System.Collections.ObjectModel.Collection(Of MyType)

    Public Function FindByActivityKey(ByVal searchValue As Integer) As MyType
        Return (From P In Me Order By P.ActivityPin.PrimaryKey = searchValue).First
    End Function

End Class

Suggestions?

Answer 1

Replace First() with FirstOrDefault() as in

Return (From P In Me Order By P.ActivityPin.PrimaryKey = searchValue) _
       .FirstOrDefault()

First() assumes there is at least one element and throws an exception if it can’t find any. FirstOrDefault() returns Nothing by default.