Check for read-only or hidden fields in DetailsView that are not in the DataKey collection.

    Protected Sub DetailsView1_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles DetailsView1.PreRender
        Try
            'Catch error when an old .NET Framework doesn't have a DetailsView.DataSourceObject available.
            Dim FrameworkErrorCatcher As Object = sender.DataSourceObject
        Catch
            Exit Sub
        End Try
        If TypeOf sender.DataSourceObject Is ObjectDataSource Then
            Dim DetailsViewDataSource As ObjectDataSource = sender.DataSourceObject
            Dim SourceUpdateMethodName As String = DetailsViewDataSource.UpdateMethod
            If String.IsNullOrEmpty(SourceUpdateMethodName) = False Then
                For Each DetailsViewDataControlField As DataControlField In sender.Fields
                    If TypeOf DetailsViewDataControlField Is BoundField Then
                        Dim DetailsViewBoundField As BoundField = DetailsViewDataControlField
                        Dim FieldName As String = DetailsViewBoundField.DataField
                        If DetailsViewBoundField.ReadOnly = True Or DetailsViewBoundField.Visible = False Then
                            Dim DataKeyIndex As Integer = Array.IndexOf(sender.DataKeyNames, FieldName)
                            If DataKeyIndex = -1 Then
                                Throw New ApplicationException(String.Format("Read-only or hidden field {0} is not in the {1} DateKey collection.  This field will not be returned during updates.", FieldName, sender.ID))
                            End If
                        End If
                    End If
                Next DetailsViewDataControlField
            End If
        End If
    End Sub