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trims30 asked on

Getting Error when Updating AccessDataSource via Gridview in asp.net

I am working in ASP.Net - Visual Studio 2008 - VB Code

Have a Gridview bound to an AccessDataSource and have configured it to allow Updating

It works correctly and updates columns as long as all grid columns (except Primary Key) are set to ReadOnly=False
Setting one or more columns to ReadOnly=True gives me the error:
You tried to assign the Null value to a variable that is not a Variant data type

My guess is that the ReadOnly fields are trying to put Null values into database fields on update.

How do I get around this problem??


Lee
ASP.NET

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trims30

8/22/2022 - Mon
ASKER CERTIFIED SOLUTION
Todd Gerbert

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ASKER
trims30

Great, THANK YOU, that worked for me but caused another problem in my project.

In the RowUpdating Event I'm doing a calculation referencing one of the readonly columns and am getting Zero for the readonly item.

In code below, "LastMeter" is ReadOnly and "MeterInput" and "UsageInput" are editable.

How do I get value of "LastMeter" during Update if it's ReadOnly??

Lee

 Private Sub GridView1_RowUpdating(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewUpdateEventArgs) Handles GridView1.RowUpdating

        If e.NewValues("MeterInput") > e.NewValues("LastMeter") Then
            e.NewValues("UsageInput") = e.NewValues("MeterInput") - e.NewValues("LastMeter")
        End If

    End Sub
End Class
ASKER
trims30

OOPS - after looking at my code found I was using e.NewValues("LastMeter") rather than e.OldValues("LastMeter")  All is working now.

Thank you
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