CheckBox column click

[Administrator]

I have a datagrid in my column that has one DataGridBoolColumn (check box) and several text columns. I created bool column with a following code:

Dim Col As New DataGridBoolColumn()

Col.HeaderText = "Select"
Col.MappingName = "Select"

Col.AllowNull = False

Col.TrueValue = True
Col.FalseValue = False

tableStyle.GridColumnStyles.Add(unboundColStyle)

After this I have a column with a check box. Now I'd like to get rid of this DBNull value that comes when I click the check box. I added this code to the mouseDown event in the grid:

Dim hti As DataGrid.HitTestInfo = Me.dgr.HitTest(e.X, e.Y)

Try

If hti.Type = DataGrid.HitTestType.Cell AndAlso hti.Column = 0 Then

Me.dgr(hti.Row, hti.Column) = Not CBool(dgr(hti.Row, hti.Column))

End If

Catch ex As Exception
MessageBox.Show(ex.ToString())
End Try

This code crashes because checkbox has a value DBNull. So, how to get rid of this DBNull value? And does anyone know why the check box is disabled(gray) at the beginning?

[Administrator]

The grey box means the value is NULL.

> I have a datagrid in my column that has one DataGridBoolColumn (check box) and several text columns. I created bool column with a following code:
>
> Dim Col As New DataGridBoolColumn()
>
> Col.HeaderText = "Select"
> Col.MappingName = "Select"
>
> Col.AllowNull = False
>
> Col.TrueValue = True
> Col.FalseValue = False
>
> tableStyle.GridColumnStyles.Add(unboundColStyle)
>
> After this I have a column with a check box. Now I'd like to get rid of this DBNull value that comes when I click the check box. I added this code to the mouseDown event in the grid:
>
>
> Dim hti As DataGrid.HitTestInfo = Me.dgr.HitTest(e.X, e.Y)
>
> Try
>
> If hti.Type = DataGrid.HitTestType.Cell AndAlso hti.Column = 0 Then
>
> Me.dgr(hti.Row, hti.Column) = Not CBool(dgr(hti.Row, hti.Column))
>
> End If
>
> Catch ex As Exception
> MessageBox.Show(ex.ToString())
> End Try
>
> This code crashes because checkbox has a value DBNull. So, how to get rid of this DBNull value? And does anyone know why the check box is disabled(gray) at the beginning?