topic Re: CHECK FOR NULL IN VB in ArcObjects SDK Questions

CHECK FOR NULL IN VB

DonJohnson — Mon, 20 Sep 2010 18:23:23 GMT

I am trying to identify a NULL value in a string field and assign a value.

IsNull = True is causing an error.

Any other suggestions?

Re: CHECK FOR NULL IN VB

NeilClemmons — Sat, 11 Dec 2021 18:16:59 GMT

The following is VB.NET.

    Public Shared Function GetStringValue(ByVal value As Object) As String
        If value Is DBNull.Value Then
            Return String.Empty
        Else
            Return Convert.ToString(value)
        End If
    End Function

Re: CHECK FOR NULL IN VB

DonJohnson — Mon, 20 Sep 2010 18:44:34 GMT

I am using ModelBuilder and have the following:

Dim ROAD as String
ROAD = [ROAD_NAME]

if isNull(ROAD) = True then
ROAD = "NONE"
End If

Re: CHECK FOR NULL IN VB

JamesCrandall — Sat, 11 Dec 2021 18:17:02 GMT

Not familiar with ModelBuilder, but the VB.NET function to check for null values is the IsDBNull function. Maybe something like this? (although I am not sure about getting/setting your "[ROAD_NAME]" value):

Dim ROAD As String
If Not IsDBNull([ROAD_NAME]) Then
  ROAD = [ROAD_NAME]
Else
  ROAD = "NONE"
End If

I am using ModelBuilder and have the following:

Dim ROAD as String
ROAD = [ROAD_NAME]

if isNull(ROAD) = True then
ROAD = "NONE"
End If

Re: CHECK FOR NULL IN VB

JohnHauck — Tue, 21 Sep 2010 15:25:09 GMT

Please use the following:

Dim ROAD as String
If IsNull( [ROAD_NAME]) Then
ROAD = "NONE"
Else
ROAD = [ROAD_NAME]
End If

Re: CHECK FOR NULL IN VB

EllenTejan — Thu, 28 Mar 2013 13:42:37 GMT

Thank you don

I imbeded

isNull(ROAD) = True

into my expression and it worked for me.

Ellen