Capture ADO.NET Entities exceptions with direct binding

[antonio barbero]

Hello every body.

I have a RadGridView directly bound to a Ado.Net Entity. Maybe that's not best practice but I have to.

That entity have a property that does not allow null values:

[EdmScalarPropertyAttribute(EntityKeyProperty=false, IsNullable=false)]
[DataMemberAttribute()]
public global::System.String VCOCDC
{
   get { return _VCOCDC;}
   set
   {
     OnVCOCDCChanging(value);
     ReportPropertyChanging("VCOCDC");
     _VCOCDC = StructuralObject.SetValidValue(value, false);
     ReportPropertyChanged("VCOCDC");
     OnVCOCDCChanged();
   }
}

That property is bound to a GridViewComboBoxColumn:

<telerik:GridViewComboBoxColumn Header="{x:Static resc:Resources.Voce}"
   Width="200"
  DisplayMemberPath="VCODSC"
    SelectedValueMemberPath="VCOCDC"
    DataMemberBinding="{Binding VCOCDC}"
    Name="cl_VCOCDC"
    IsGroupable="False"
    IsComboBoxEditable="False"
/>

When inserting a new row on the grid (BeginInsert()), if the user leaves the current row without to choose a value on the combobox , an exception is raised at the row:

 _VCOCDC = StructuralObject.SetValidValue(value, false);

I can't capture the exception, unless i set a global handler, but even so, I would not know what to do, so the application quit.

Questions:

How can I prevent this exception and enforce the user to select a correct value or she can't leave the field? I tried the RowValidating event but that exception is fired before the RowValidating event is raised.

Best Regards

[Nedyalko Nikolov]

Hello antonio barbero,

The problem is that value for this property is not valid. This validation is performed between CellValidating and CellValidated events.
Could you please try to handle this case within CellValidating event?
I'm sure that exception won't be raised.

Regards,
Nedyalko Nikolov
the Telerik team

[AndyL]

Hi,
Is there any way to handle this exception on entity class level without writing extra validation code   in CellValidating

 

Thanks,

Andy

[Nedyalko Nikolov]

Hello Andyl,

I'll try to clarify the editing mechanism. CellValidating event is fired just before the actual commit. You could use this event to do UI layer validation (without call to property setter). Then RadGridView calls BindingExpression.UpdateSource() method, which takes care about the commit (calls setter) and does some custom DataAnnotations validation. Then CellValidated event is raised with the result of this Data layer validation.
In other words RadGridView has no control over you BO property setters, just calls then in a right moment.

All the best,
Nedyalko Nikolov
the Telerik team