Validation with business rules in dataset

[Ubaldo]

I've got a simple RadGridView bound to a DataTable (through a BindingSource); standard and easy way to put a gridview on a form dragging it from datasources box.
I've implemented my business rule validation in the datatable, as below:

Private Sub OperazioniDataTable_ColumnChanging(ByVal sender As System.Object, ByVal e As System.Data.DataColumnChangeEventArgs) Handles Me.ColumnChanging
  Debug.Print("ColumnChanging: column=" & e.Column.ColumnName)
  If (e.Column.ColumnName = Me.impovalColumn.ColumnName) Then
    If CType(e.ProposedValue, Decimal) = 0 Then
      e.Row.SetColumnError(e.Column, "Inserire un importo diverso da zero")
    Else
      e.Row.SetColumnError(e.Column, "")
    End If
  End If
End Sub

When I edit the [impoval] cell and enter 0, moving to another cell/row raises the ColumnChanging event, but no feedback at all on the grid.
Another issue: if I press [Escape] key in the cell, the value is not restored to the old one.
In the standard MS grid I get feedback and restore behaviour.
I would like to know the best practices to enforce data validation (on single cells and on row, moving away from a cell/row and/or trying to close a form, etc.), possibly avoiding to put rules in the gridview events, in order to keep all the business rules validation code in the data transfer objects.
Please don't suggest to create separate business objects, as I want to avoid this coding overhead.
TIA
Ubaldo

[Svett]

Hello Ubaldo,

You should validate the data through the grid or your data source should implement the IDataErrorInfo interface. You should use the the CellValidating event to achieve the desired scenario:

Private Sub radGridView1_CellValidating(ByVal sender As Object, ByVal e As CellValidatingEventArgs)
    If e.Column.Name = "ID" Then
        Dim value As Decimal = Convert.ToDecimal(e.Value)

        If value = 0 Then
            e.Cancel = True
            e.Row.ErrorText = "Inserire un importo diverso da zero"
            e.Row.Cells("ID").Style.CustomizeBorder = True
            e.Row.Cells("ID").Style.DrawBorder = True
            e.Row.Cells("ID").Style.BorderGradientStyle = Telerik.WinControls.GradientStyles.Solid
            e.Row.Cells("ID").Style.BorderWidth = 3
            e.Row.Cells("ID").Style.BorderColor = Color.Red
        Else
            e.Row.ErrorText = Nothing
            e.Row.Cells("ID").Style.Reset()
        End If
    End If
End Sub

I hope this helps.

Greetings,
Svett
the Telerik team

[Richard Slade]

Hello,

In addition to Svett's reply, there is a Code Library Project here on using RadGridView and IDataErrorInfo
Regards,
Richard