CODEWITHSUNDEEP
.netvb.net
ic3b3rg
ic3b3rg

Reputation: 14927

Generic Function with Special Case for String

What's the best way to handle this situation:

I have this generic function

Function FieldValue(Of T)(row As DataRow,fieldName As String) As T
  Return If(row.IsNull(fieldName),Nothing,CType(row(fieldName),T))
End Function

in the special case where the field value is null and T is String, I want to return String.Empty instead of Nothing.

Upvotes: 1

Views: 124

Answers (1)

Xavier Poinas
Xavier Poinas

Reputation: 19733

I think the easiest way is to provide a specific function for T = string:

Function FieldValue(row As DataRow ,fieldName As String) As String
  Return If(row.IsNull(fieldName), String.Empty, CType(row(fieldName), String))
End Function

(on top of your existing generic function)

Here's another option:

Function FieldValue(Of T)(row As DataRow,fieldName As String) As T
    If GetType(T) = GetType(String) And row.IsNull(fieldName) Then
        Return CType(CType(String.Empty, Object), T)
    Else
        Return If(row.IsNull(fieldName), Nothing, CType(row(fieldName), T))
    End If
End Function

Upvotes: 2

Related Questions