GridColumn.Validate Event

Enables you to validate the active editor’s value.

Namespace: DevExpress.Xpf.Grid

Assembly: DevExpress.Xpf.Grid.v20.2.dll

NuGet Packages: DevExpress.WindowsDesktop.Wpf.Grid.Core, DevExpress.Wpf.Grid.Core

Declaration

C#

public event GridCellValidationEventHandler Validate

VB.NET

Public Event Validate As GridCellValidationEventHandler

Event Data

The Validate event's data class is GridCellValidationEventArgs. The following properties provide information specific to this event:

Property	Description
CancellationToken	Gets an object that notifies that the Update operation should be canceled. Inherited from GridRowValidationEventArgs.
Cell	Gets the CellValue object consisting of information about the cell being processed.
CellValue	Gets the cell’s old valid value.
Column	Gets the column that contains the processed cell.
Culture	Gets the culture related to the validation. Inherited from ValidationEventArgs.
ErrorContent	Gets or sets an object that describes the validation error. Inherited from ValidationEventArgs.
ErrorType	Gets or sets the error icon type. Inherited from ValidationEventArgs.
Handled	Gets or sets a value that indicates the present state of the event handling for a routed event as it travels the route. Inherited from RoutedEventArgs.
IsValid	Gets or sets a value specifying whether the value is valid. Inherited from ValidationEventArgs.
OriginalSource	Gets the original reporting source as determined by pure hit testing, before any possible Source adjustment by a parent class. Inherited from RoutedEventArgs.
RoutedEvent	Gets or sets the RoutedEvent associated with this RoutedEventArgs instance. Inherited from RoutedEventArgs.
Row	Gets the processed row. Inherited from GridRowValidationEventArgs.
RowHandle	Gets the processed row’s handle. Inherited from GridRowValidationEventArgs.
Source	Gets or sets a reference to the object that raised the event. Inherited from RoutedEventArgs.
UpdateRowResult	Gets or sets a task that allows you to asynchronously post changes to an underlying data source (database). Inherited from GridRowValidationEventArgs.
UpdateSource	Gets the action that caused the validation. Inherited from ValidationEventArgs.
UseCancellationToken	Gets or sets whether the Update operation can be canceled. Inherited from GridRowValidationEventArgs.
Value	Gets the editor’s value. Inherited from ValidationEventArgs.

The event data class exposes the following methods:

Method	Description
InvokeEventHandler(Delegate, Object)	When overridden in a derived class, provides a way to invoke event handlers in a type-specific way, which can increase efficiency over the base implementation. Inherited from RoutedEventArgs.
OnSetSource(Object)	When overridden in a derived class, provides a notification callback entry point whenever the value of the Source property of an instance changes. Inherited from RoutedEventArgs.
SetError(Object, ErrorType)	Marks the processed input value as invalid and displays an error within the editor with the specified error icon type. Inherited from ValidationEventArgs.
SetError(Object)	Marks the processed input value as invalid and displays an error within the editor. Inherited from ValidationEventArgs.

Remarks

When an end-user modifies the focused cell’s value and tries to save the changes (by pressing the ENTER key or moving focus to another cell), the grid validates a new value. First, this value is validated by the editor itself. Then, the column’s Validate event is raised, allowing you to manually validate the cell’s value. Note this event is not fired when changing cell values in code.

To learn more, see Cell Validation.

Related GitHub Examples

The following code snippets (auto-collected from DevExpress Examples) contain references to the Validate event.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

XAML

wpf-data-grid-validate-cell-editors/CS/DXGrid_ValidatingEditors/Window1.xaml#L15

</dxg:GridColumn>
<dxg:GridColumn FieldName="UnitPrice" Validate="GridColumn_Validate">
    <dxg:GridColumn.EditSettings>

C#

mvvm-how-to-use-validationrules-to-validate-values-entered-into-gridcontrol-e3233/CS/WpfApplication1/GridColumnValidationHelper.cs#L30

    return;
column.Validate -= new GridCellValidationEventHandler(OnColumnValidate);
if(e.NewValue != null)

VB.NET

mvvm-how-to-use-validationrules-to-validate-values-entered-into-gridcontrol-e3233/VB/WpfApplication1/GridColumnValidationHelper.vb#L35

End If
RemoveHandler column.Validate, AddressOf OnColumnValidate
If e.NewValue IsNot Nothing Then