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DataGridView.RowValidating Event

Occurs when a row is validating.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

'Declaration
Public Event RowValidating As DataGridViewCellCancelEventHandler

This event is analogous to the Control.Validating event. Use this event to perform validation on all the values of a row. If the row does not pass validation, set the CancelEventArgs.Cancel property to true. Canceling this event prevents the RowValidated, Control.Validating, and Control.Validated events from occurring, and also prevents the user from leaving the invalid row and prevents the row from being saved to an external data source in data bound mode.

For more information about handling events, see Consuming Events.

The following code example uses RowValidating to check if valid track and release dates are entered.

Private Sub ValidateByRow(ByVal sender As Object, _
    ByVal data As DataGridViewCellCancelEventArgs) _
    Handles songsDataGridView.RowValidating

    Dim row As DataGridViewRow = _
        songsDataGridView.Rows(data.RowIndex)
    Dim trackCell As DataGridViewCell = _
        row.Cells(songsDataGridView.Columns("Track").Index)
    Dim dateCell As DataGridViewCell = _
        row.Cells(songsDataGridView.Columns("Release Date").Index)
    data.Cancel = Not (IsTrackGood(trackCell) _
        AndAlso IsDateGood(dateCell))
End Sub 

Private Function IsTrackGood(ByRef cell As DataGridViewCell) As Boolean 

    If cell.Value.ToString().Length = 0 Then
        cell.ErrorText = "Please enter a track"
        songsDataGridView.Rows(cell.RowIndex).ErrorText = _
            "Please enter a track" 
        Return False 
    ElseIf cell.Value.ToString().Equals("0") Then
        cell.ErrorText = "Zero is not a valid track"
        songsDataGridView.Rows(cell.RowIndex).ErrorText = _
            "Zero is not a valid track" 
        Return False 
    ElseIf Not Integer.TryParse( _
        cell.Value.ToString(), New Integer()) Then
        cell.ErrorText = "A Track must be a number"
        songsDataGridView.Rows(cell.RowIndex).ErrorText = _
            "A Track must be a number" 
        Return False 
    End If 
    Return True 
End Function 

Private Function IsDateGood(ByRef cell As DataGridViewCell) As Boolean 

    If cell.Value Is Nothing Then
        cell.ErrorText = "Missing date"
        songsDataGridView.Rows(cell.RowIndex).ErrorText = _
            "Missing date" 
        Return False 
    Else 
        Try
            DateTime.Parse(cell.Value.ToString())
        Catch ex As FormatException

            cell.ErrorText = "Invalid format"
            songsDataGridView.Rows(cell.RowIndex).ErrorText = _
                "Invalid format" 

            Return False 
        End Try 
    End If 
    Return True 
End Function

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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