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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)

'Declaration
Public Delegate Sub DataGridViewCellCancelEventHandler ( _
	sender As Object, _
	e As DataGridViewCellCancelEventArgs _
)
'Usage
Dim instance As New DataGridViewCellCancelEventHandler(AddressOf HandlerMethod)

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 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

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0
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