Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
public delegate void DataGridViewRowErrorTextNeededEventHandler( Object sender, DataGridViewRowErrorTextNeededEventArgs e )
- Type: System.Object
The source of the event.
- Type: System.Windows.Forms.DataGridViewRowErrorTextNeededEventArgs
A DataGridViewRowErrorTextNeededEventArgs that contains the event data.
The RowErrorTextNeeded event occurs only when the DataGridView control DataSource property is set or its VirtualMode property is true. Handling the RowErrorTextNeeded event is useful when you want to determine the error for a row depending on its state and the values it contains.
When you handle the RowErrorTextNeeded event and specify error text in the handler, an error glyph appears in the row header unless the DataGridView.ShowRowErrors property is set to false. When the user moves the mouse pointer over the error glyph, the error text appears in a ToolTip.
You can use the DataGridViewRowErrorTextNeededEventArgs.RowIndex property to determine the state or value of a row, and use this information to change or modify the DataGridViewRowErrorTextNeededEventArgs.ErrorText property. This property is initialized with the value of the row ErrorText property, which the event value overrides.
Handle the RowErrorTextNeeded event when working with large amounts of data to avoid the performance penalties of setting the row ErrorText value for multiple rows. For more information, see Best Practices for Scaling the Windows Forms DataGridView Control.
For more information about handling events, see Consuming Events.
When you create a 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.