How to pass a null and another value into a function

[vertigo262]

Ok, I keep running into this problem

In my aspx I am calling a simple function.

But the problem is, that the function is either, string, integer, etc.

If there's null's in the data, the function explodes because it's set to a string or integer, etc.

How can I make the function accept both a null, and another data type so that I can

write some if then's to do different things if it is null or another data type.

Here is the code to give you an idea

 
.aspx code

<%# GetRatingFormat(Container.DataItem("Rating") %>


.vb code

Function GetRatingFormat(ByVal UserRating As Decimal) As String

        If IsNothing(UserRating) Or IsDBNull(UserRating) Then
            Return "Not Yet Rated"
        Else
            Return Format(UserRating, "0.0") & "%"
        End If


    End Function

UserRating needs to accept both null and decimal

any help would be greatly appreciated

[danp129]

Try declaring UserRating as Object.

[vertigo262]

Hi Dan,

thanks for the reply. that's how I had it originally. The object was dropping the value of the decimal and making it a 0.0

[danp129]

Format requires a numeric data type and it was likely being passed a string. This should work.

    Function GetRatingFormat(ByVal userRating As Object) As String
        Dim decimalRating As Decimal = Nothing

        If TypeOf userRating Is Decimal Then
            decimalRating = DirectCast(userRating, Decimal)
        ElseIf IsNumeric(userRating) Then
            decimalRating = CDec(userRating)
        End If

        If decimalRating = Nothing Then
            Return "Not Yet Rated"
        Else
            Return Format(decimalRating, "0.0") & "%"
        End If

    End Function

[vertigo262]

Works great!

I don't really understand what's going on in your code, but it works. Was hoping there was a generic way of doing it in here "(ByVal userRating As Object"

in case I want to do other functions with both null and datatype.

But I can work with this :)

Your help is much appreciated!

Thank you

[danp129]

You can use overloads if you want.

     Overloads Function GetRatingFormat(ByVal userRating As Object) As String
          ' Your code here
     End Function

     Overloads Function GetRatingFormat(ByVal userRating As String) As String
          ' Your code here
     End Function

     Overloads Function GetRatingFormat(ByVal userRating As Decimal) As String
          ' Your code here
     End Function

' etc...

[Frinavale]

I would have gone with Overloading the method or even using Optional parameters. There are quite a few ways to solve this problem :)

-Frinny

[vertigo262]

wouldn't happen to have an example code of Optional Parameters?

[Frinavale]

Something like this

Function GetRatingFormat(Optional ByVal userRating  As Object = Nothing, Optional ByVal userRatingDec As Decimal = 0, Optional ByVal  userRatingStr As String = "")
  'In this function you will have to validate each
  'parameter to determine which one has bee provided
End Function

After typing out the example...I don't like this recommendation any more. The overloaded version is your best approach in my opinion.

-Frinny

[vertigo262]

OK!!!!! thanks for the input Frinny and everyone else!