DataGridViewCellCancelEventHandler Delegate

 

Represents the method that will handle the CellBeginEdit and RowValidating events of a DataGridView.

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

Public Delegate Sub DataGridViewCellCancelEventHandler (
	sender As Object,
	e As DataGridViewCellCancelEventArgs
)

Parameters

sender
Type: System.Object

The source of the event.

e
Type: System.Windows.Forms.DataGridViewCellCancelEventArgs

A DataGridViewCellCancelEventArgs that contains the event data.

When you create a DataGridViewCellCancelEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event-handler delegates, see NIB: Events and Delegates.

The following code example uses a DataGridViewCellCancelEventHandler delegate 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
Available since 2.0
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