[thelist] Null Value from a database to a string?

[David Travis]

Casey,

In addition to the solution I offered I must add that setting a default
value in this column so an empty field will be an empty string and not null
provides much easier code.

Note that some databases require special handling when it comes to null
values, so either way it is recommended (sometimes) not to allow them by
using default values.

David Travis.

-----Original Message-----
From: thelist-bounces at lists.evolt.org
[mailto:thelist-bounces at lists.evolt.org] On Behalf Of David Travis
Sent: Wednesday, December 29, 2004 10:28 PM
To: 'Casey Crookston'; thelist at lists.evolt.org
Subject: RE: [thelist] Null Value from a database to a string?

Hi Casey,

You should have something like this:

Dim adrs2 as String
If TypeOf myRow["adrs2"] Is DbNull Then
	adrs2 = String.Empty
Else
	adrs2 = myRow["adrs2"].ToString()
End If

I am writing this code without testing it, and it was a while since I worked
with VB.NET, so I am not sure this is 100% working, but that's the main
idea.

Good Luck!
David Travis.


-----Original Message-----
From: thelist-bounces at lists.evolt.org
[mailto:thelist-bounces at lists.evolt.org] On Behalf Of Casey Crookston
Sent: Wednesday, December 29, 2004 7:36 PM
To: thelist at lists.evolt.org
Subject: [thelist] Null Value from a database to a string?

asp.net in vb...

I'm populating a form from a database row.  There's a column in the db for
address and address2 incase the user needs a second line for their address.
In the db address2 is allowed a null value, but when trying to populate the
form I get this error:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Cast from type 'DBNull' to type 'String' is not valid.
Description: An unhandled exception occurred during the execution of the
current web request. Please review the stack trace for more information
about the error and where it originated in the code.

Exception Details: System.InvalidCastException: Cast from type 'DBNull' to
type 'String' is not valid.

Source Error:

Line 95:   baddress2.text=mySingleMemberDtr("b_address2")
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Makes sense, I guess.  It won't let a null value be passed into a text
string.  What can I do to allow a null value to be entered. I REALLY don't
want to have to force the user to enter something like "n/a" into the field
if it is empty.  Or, what's the best way to have a value look empty when
it's not?

Thanks!


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