Coalesce for VB.Net

Here are two simple functions (4 functions, 2 with 2 overloads) that will create a Coalesce command for VB.Net similar to what exists in SQL. These functions will return the first non null value in either an array of objects or a generic list of objects.

''' <summary>
''' Returns the first non null value in the object list.  If all objects in the list are null, then a null will be returned.
''' </summary>
''' <param name="objList"></param>
Public Shared Function Coalesce(ByVal objList() As Object) As Object
    For Each o As Object In objList
        If o IsNot Nothing Then
            Return o
        End If
    Next
    Return New Object
End Function

''' <summary>
''' Returns the first non null value in the object list.  If all objects in the list are null, then a null will be returned.
''' </summary>
''' <param name="objList"></param>
Public Shared Function Coalesce(ByVal objList As List(Of Object)) As Object
    For Each o As Object In objList
        If o IsNot Nothing Then
            Return o
        End If
    Next
    Return New Object
End Function

''' <summary>
''' Returns the first non null value in the object list.  If all objects in the list are null the the defaultValue variable specified
''' will be returned.
''' </summary>
''' <param name="objList"></param>
''' <param name="defaultValue"></param>
Public Shared Function Coalesce(ByVal objList() As Object, ByVal defaultValue As Object) As Object
    For Each o As Object In objList
        If o IsNot Nothing Then
            Return o
        End If
    Next
    Return defaultValue
End Function

''' <summary>
''' Returns the first non null value in the object list.  If all objects in the list are null the the defaultValue variable specified
''' will be returned.
''' </summary>
''' <param name="objList"></param>
''' <param name="defaultValue"></param>
Public Shared Function Coalesce(ByVal objList() As List(Of Object), ByVal defaultValue As Object) As Object
    For Each o As Object In objList
        If o IsNot Nothing Then
            Return o
        End If
    Next
    Return defaultValue
End Function

Please note that we won't show your email to others, or use it for sending unwanted emails. We will only use it to render your Gravatar image and to validate you as a real person.

Leave a comment