GridViewBase.ValidateCellCommand Property

Gets or sets a command that allows you to validate the focused cell’s data.

Namespace: DevExpress.Xpf.Grid

Assembly: DevExpress.Xpf.Grid.v24.2.dll

NuGet Package: DevExpress.Wpf.Grid.Core

Declaration

C#

public ICommand<RowCellValidationArgs> ValidateCellCommand { get; set; }

VB.NET

Public Property ValidateCellCommand As ICommand(Of RowCellValidationArgs)

Property Value

Type	Description
ICommand<RowCellValidationArgs>	A command that allows you to validate the focused cell’s data.

Remarks

Bind a command to the ValidateCellCommand property to maintain a clean MVVM pattern. The command works like a ValidateCell event handler and allows you to validate cell values in a View Model.

The command bound to the ValidateCellCommand property is executed before the focused cell’s modified value is posted to a data source and allows you to validate its new value.

Note

When you use a custom CellTemplate, input validation is supported only if the template contains a BaseEdit class descendant declared as demonstrated in the following topic: Custom In-Place Cell Editors.

The RowCellValidationArgs.NewValue property returns the focused cell’s new value. To indicate that the new value is invalid, set the RowCellValidationArgs.Result property to an error description.

Set the DataViewBase.AllowLeaveInvalidEditor property to true to allow users to close an editor that did not pass validation.

Refer to the following help topic for more information: Cell Validation.

Example

This example shows how to validate the focused cell’s value.

View Example: How to Validate Cell Editors

XAML

<dxg:GridControl ItemsSource="{Binding ProductList}">
    <dxg:GridControl.Columns>
        <dxg:GridColumn FieldName="ProductName">
            <dxg:GridColumn.EditSettings>
                <dxe:TextEditSettings AllowNullInput="False" />
            </dxg:GridColumn.EditSettings>
        </dxg:GridColumn>
        <dxg:GridColumn FieldName="UnitPrice" >
            <dxg:GridColumn.EditSettings>
                <dxe:SpinEditSettings DisplayFormat="c2" />
            </dxg:GridColumn.EditSettings>
        </dxg:GridColumn>
        <dxg:GridColumn FieldName="Discontinued" />
    </dxg:GridControl.Columns>
    <dxg:GridControl.View>
        <dxg:TableView AutoWidth="True"
                       ValidateCellCommand="{Binding ValidateCellCommand}"/>
    </dxg:GridControl.View>
</dxg:GridControl>

C#

using DevExpress.Mvvm;
using DevExpress.Mvvm.DataAnnotations;
using DevExpress.Mvvm.Xpf;
// ...
public class MainViewModel : ViewModelBase {
// ...
    [Command]
    public void ValidateCell(RowCellValidationArgs args) {
        if(args.FieldName != nameof(Product.UnitPrice) || !((Product)args.Item).Discontinued)
            return;
        var cellValue = (double)args.OldValue;
        var discount = 100 - Convert.ToDouble(args.NewValue) / cellValue * 100;
        if(discount > 0 && discount <= 30)
            return;

        var error = discount < 0
            ? $"The price cannot be greater than {cellValue}"
            : $"The discount cannot be greater than 30% ({cellValue * 0.7}). Please correct the price.";
        args.Result = new ValidationErrorInfo(error, ValidationErrorType.Critical);
    }
}

VB.NET

Imports DevExpress.Mvvm
Imports DevExpress.Mvvm.DataAnnotations
Imports DevExpress.Mvvm.Xpf
' ...
Public Class MainViewModel
    Inherits ViewModelBase
' ...
    <Command>
    Public Sub ValidateCell(ByVal args As RowCellValidationArgs)
        If Not Equals(args.FieldName, NameOf(Product.UnitPrice)) OrElse Not CType(args.Item, Product).Discontinued Then Return
        Dim cellValue = CDbl(args.OldValue)
        Dim discount = 100 - Convert.ToDouble(args.NewValue) / cellValue * 100
        If discount > 0 AndAlso discount <= 30 Then Return
        Dim [error] = If(discount < 0, $"The price cannot be greater than {cellValue}", $"The discount cannot be greater than 30% ({cellValue * 0.7}). Please correct the price.")
        args.Result = New ValidationErrorInfo([error], ValidationErrorType.Critical)
    End Sub
End Class

Related GitHub Examples

The following code snippet (auto-collected from DevExpress Examples) contains a reference to the ValidateCellCommand property.

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/ValidateCell_MVVM/MainWindow.xaml#L31

    <dxg:TableView AutoWidth="True"
                   ValidateCellCommand="{Binding ValidateCellCommand}"/>
</dxg:GridControl.View>