GridViewBase.ValidateRow Event

Allows you to specify whether the focused row’s data is valid, and whether the row can lose focus.

Namespace: DevExpress.Xpf.Grid

Assembly: DevExpress.Xpf.Grid.v19.2.dll

Declaration

C#

public event GridRowValidationEventHandler ValidateRow

VB.NET

Public Event ValidateRow As GridRowValidationEventHandler

Event Data

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

Property	Description
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 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.
RowHandle	Gets the processed row’s handle.
Source	Gets or sets a reference to the object that raised the event. Inherited from RoutedEventArgs.
UpdateSource	Gets the action that caused the validation. Inherited from ValidationEventArgs.
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)	Displays an error within the editor. Inherited from ValidationEventArgs.
SetError(Object)	Displays an error within the editor. Inherited from ValidationEventArgs.

Remarks

Row validation is performed within the ValidateRow event handler. This event is fired after the focused row’s data has been modified and it is about to lose focus. To manually force row validation, call the DataViewBase.CommitEditing method.

The GridRowValidationEventArgs.Row property returns the processed row. The GridRowValidationEventArgs.RowHandle property returns the row’s handle. After cell values are obtained, you can verify whether these values meet your validity criteria. If the row fails validation, set the event’s IsValid parameter to false. Otherwise, leave the IsValid parameter set to true.

To learn more, see Row Validation.

Example

This example shows how to check the validity of data entered by end users into a data row. The GridViewBase.ValidateRow and GridViewBase.InvalidRowException events are handled to validate the focused row’s data, and if it is invalid, prevent the row focus from being moved to another row until invalid values are corrected.

Since the Task class does not support error notifications, it implements the IDXDataErrorInfo interface, providing two members to get error descriptions for the entire row and for individual cells (data source fields). This displays error icons within cells with invalid values. Pointing to such an error icon displays a tooltip with an error description.

Note

A complete sample project is available at https://github.com/DevExpress-Examples/how-to-validate-data-rows-e1593.

Window1.xaml

<Window x:Class="DXGrid_ValidateRow.Window1" 
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid" 
    Title="Window1" Height="300" Width="500">
    <Grid>
        <dxg:GridControl x:Name="grid">
            <dxg:GridControl.Columns>
                <dxg:GridColumn FieldName="TaskName" />
                <dxg:GridColumn FieldName="StartDate" />
                <dxg:GridColumn FieldName="EndDate" />
            </dxg:GridControl.Columns>
            <dxg:GridControl.View>
                <dxg:TableView AutoWidth="True" 
                               ValidateRow="TableView_ValidateRow" 
                               InvalidRowException="TableView_InvalidRowException" />
            </dxg:GridControl.View>
        </dxg:GridControl>
    </Grid>
</Window>

Window1.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Data;
using DevExpress.Xpf.Grid;
using DevExpress.XtraEditors.DXErrorProvider;

namespace DXGrid_ValidateRow {
    public partial class Window1 : Window {
        public Window1() {
            InitializeComponent();
            grid.ItemsSource = TaskList.GetData();
        }

        private void TableView_ValidateRow(object sender, GridRowValidationEventArgs e) {
            DateTime startDate = ((Task)e.Row).StartDate;
            DateTime endDate = ((Task)e.Row).EndDate;
            e.IsValid = startDate < endDate;
        }

        private void TableView_InvalidRowException(object sender, InvalidRowExceptionEventArgs e) {
            e.ExceptionMode = ExceptionMode.NoAction;
        }
    }

    public class TaskList {
        public static List<Task> GetData() {
            List<Task> data = new List<Task>();
            data.Add(new Task() { TaskName = "Complete Project A",
                StartDate = new DateTime(2009, 7, 17), EndDate = new DateTime(2009, 7, 10) });
            data.Add(new Task() { TaskName = "Test Website",
                StartDate = new DateTime(2009, 7, 10), EndDate = new DateTime(2009, 7, 12) });
            data.Add(new Task() { TaskName = "Publish Docs",
                StartDate = new DateTime(2009, 7, 4), EndDate = new DateTime(2009, 7, 6) });
            return data;
        }
    }

    public class Task : IDXDataErrorInfo {
        public string TaskName { get; set; }
        public DateTime StartDate { get; set; }
        public DateTime EndDate { get; set; }
        void IDXDataErrorInfo.GetError(ErrorInfo info) {
            if (StartDate > EndDate) {
                SetErrorInfo(info,
                    "Either StartDate or EndDate should be corrected.",
                    ErrorType.Critical);
            }
        }
        void IDXDataErrorInfo.GetPropertyError(string propertyName, ErrorInfo info) {
            switch (propertyName) {
                case "StartDate":
                    if (StartDate > EndDate)
                        SetErrorInfo(info,
                            "StartDate must be less than EndDate",
                            ErrorType.Critical);
                    break;
                case "EndDate":
                    if (StartDate > EndDate)
                        SetErrorInfo(info,
                            "EndDate must be greater than StartDate",
                            ErrorType.Critical);
                    break;
                case "TaskName":
                    if (IsStringEmpty(TaskName))
                        SetErrorInfo(info,
                            "Task name hasn't been entered",
                            ErrorType.Information);
                    break;
            }
        }
        void SetErrorInfo(ErrorInfo info, string errorText, ErrorType errorType) {
            info.ErrorText = errorText;
            info.ErrorType = errorType;
        }
        bool IsStringEmpty(string str) {
            return (str != null && str.Trim().Length == 0);
        }
    }
}

Window1.xaml.vb

Imports Microsoft.VisualBasic
Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Text
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Data
Imports System.Windows.Documents
Imports System.Windows.Input
Imports System.Windows.Media
Imports System.Windows.Media.Imaging
Imports System.Windows.Navigation
Imports System.Windows.Shapes
Imports System.Data
Imports DevExpress.XtraEditors.DXErrorProvider

Namespace DXGrid_ValidateRow
    Partial Public Class Window1
        Inherits Window
        Public Sub New()
            InitializeComponent()
            grid.ItemsSource = TaskList.GetData()
        End Sub

        Private Sub TableView_ValidateRow(ByVal sender As Object, _
            ByVal e As DevExpress.Xpf.Grid.GridRowValidationEventArgs)
                Dim startDate As DateTime = (CType(e.Row, Task)).StartDate
                Dim endDate As DateTime = (CType(e.Row, Task)).EndDate
                e.IsValid = startDate < endDate
        End Sub

        Private Sub TableView_InvalidRowException(ByVal sender As Object, _
            ByVal e As DevExpress.Xpf.Grid.InvalidRowExceptionEventArgs)
                e.ExceptionMode = DevExpress.Xpf.Grid.ExceptionMode.NoAction
        End Sub
    End Class

    Public Class TaskList
        Public Shared Function GetData() As List(Of Task)
            Dim data As New List(Of Task)()
            data.Add(New Task() With {.TaskName = "Complete Project A", _
                .StartDate = New DateTime(2009, 7, 17), .EndDate = New DateTime(2009, 7, 10)})
            data.Add(New Task() With {.TaskName = "Test Website", _
                .StartDate = New DateTime(2009, 7, 10), .EndDate = New DateTime(2009, 7, 12)})
            data.Add(New Task() With {.TaskName = "Publish Docs", _
                .StartDate = New DateTime(2009, 7, 4), .EndDate = New DateTime(2009, 7, 6)})
            Return data
        End Function
    End Class

    Public Class Task
        Implements IDXDataErrorInfo
        Private privateTaskName As String
        Public Property TaskName() As String
            Get
                Return privateTaskName
            End Get
            Set(ByVal value As String)
                privateTaskName = value
            End Set
        End Property
        Private privateStartDate As DateTime
        Public Property StartDate() As DateTime
            Get
                Return privateStartDate
            End Get
            Set(ByVal value As DateTime)
                privateStartDate = value
            End Set
        End Property
        Private privateEndDate As DateTime
        Public Property EndDate() As DateTime
            Get
                Return privateEndDate
            End Get
            Set(ByVal value As DateTime)
                privateEndDate = value
            End Set
        End Property
        Private Sub GetError(ByVal info As ErrorInfo) Implements IDXDataErrorInfo.GetError
            If StartDate > EndDate Then
                SetErrorInfo(info, _
                    "Either StartDate or EndDate should be corrected.", _
                    ErrorType.Critical)
            End If
        End Sub
        Private Sub GetPropertyError(ByVal propertyName As String, _
            ByVal info As ErrorInfo) Implements IDXDataErrorInfo.GetPropertyError
                Select Case propertyName
                    Case "StartDate"
                        If StartDate > EndDate Then
                            SetErrorInfo(info, _
                                "StartDate must be less than EndDate", _
                                ErrorType.Critical)
                        End If
                    Case "EndDate"
                        If StartDate > EndDate Then
                            SetErrorInfo(info, _
                                "EndDate must be greater than StartDate", _
                                ErrorType.Critical)
                        End If
                    Case "TaskName"
                        If IsStringEmpty(TaskName) Then
                            SetErrorInfo(info, _
                                "Task name hasn't been entered", _
                                ErrorType.Information)
                        End If
                End Select
        End Sub
        Private Sub SetErrorInfo(ByVal info As ErrorInfo, _
            ByVal errorText As String, _
            ByVal errorType As ErrorType)
                info.ErrorText = errorText
                info.ErrorType = errorType
        End Sub
        Private Function IsStringEmpty(ByVal str As String) As Boolean
            Return (str IsNot Nothing AndAlso str.Trim().Length = 0)
        End Function
    End Class
End Namespace

Related GitHub Examples

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

C#

wpf-data-grid-validate-data-rows/CS/DXGrid_ValidateRow/Window1.xaml#L10

<dxg:GridControl.View>
    <dxg:TableView AutoWidth="True" ValidateRow="TableView_ValidateRow" InvalidRowException="TableView_InvalidRowException" />
</dxg:GridControl.View>

wpf-data-grid-initialize-new-item-row-with-default-values/CS/DXGrid_NewItemRow/Window1.xaml#L12

InitNewRow="TableView_InitNewRow"
ValidateRow="TableView_ValidateRow"
InvalidRowException="TableView_InvalidRowException" />