Assembly: System.Windows.Forms (in system.windows.forms.dll)
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.
The RowErrorTextNeeded event also occurs whenever the value of the DataGridViewRow.ErrorText property is retrieved.
You can use the RowIndex property to determine the state or value of a row, and use this information to change or modify the 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.
Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.