RuleBase.CustomFormatValidationMessage Event

Occurs when the validation result message is being formatted.

Namespace: DevExpress.Persistent.Validation

Assembly: DevExpress.Persistent.Base.v24.1.dll

NuGet Package: DevExpress.Persistent.Base

Declaration

C#

public static event EventHandler<CustomFormatValidationMessageEventArgs> CustomFormatValidationMessage

VB.NET

Public Shared Event CustomFormatValidationMessage As EventHandler(Of CustomFormatValidationMessageEventArgs)

Event Data

The CustomFormatValidationMessage event's data class is DevExpress.Persistent.Validation.CustomFormatValidationMessageEventArgs.

Remarks

Handle this event to apply custom formatting to the validation result message. Use the handler’s Object parameter to access the object that is being validated, MessageFormat - to access the error message template, and ResultMessage - to specify the resulting message. Set the handler’s Handled parameter to true to cancel the default formatting.

The following Controller replaces the property name with the corresponding View Item caption in the validation message of the “MyRule” rule. This Controller activates for the Employee Detail View only.

C#

using System.Linq;
using DevExpress.ExpressApp;
using DevExpress.ExpressApp.Model;
using DevExpress.Persistent.Validation;
// ...
namespace MySolution.Module.Controllers {
    public class CustomizeValidationMessageController : ObjectViewController<DetailView, Employee> {
        protected override void OnActivated() {
            base.OnActivated();
            RuleBase.CustomFormatValidationMessage += RuleBase_CustomFormatValidationMessage;
        }
        private void RuleBase_CustomFormatValidationMessage(object sender, CustomFormatValidationMessageEventArgs e) {
            RuleBase rule = (RuleBase)sender;
            if (!e.Handled && rule.Id == "MyRule" && e.Object is Employee) {
                string propertyCaption = rule.UsedProperties[0];
                IModelViewItem modelViewItem = View.Model.Items.FirstOrDefault(x => x.Id == propertyCaption);
                propertyCaption = (modelViewItem == null) ? propertyCaption : modelViewItem.Caption;
                e.ResultMessage = e.MessageFormat.Replace("{TargetPropertyName}", propertyCaption);
                e.Handled = true;
            }
        }
        protected override void OnDeactivated() {
            base.OnDeactivated();
            RuleBase.CustomFormatValidationMessage -= RuleBase_CustomFormatValidationMessage;
        }
    }
}

VB.NET

Imports System.Linq
Imports DevExpress.ExpressApp
Imports DevExpress.ExpressApp.Model
Imports DevExpress.Persistent.Validation
' ...
Namespace MySolution.Module.Controllers
    Public Class CustomizeValidationMessageController
        Inherits ObjectViewController(Of DetailView, Employee)

        Protected Overrides Sub OnActivated()
            MyBase.OnActivated()
            AddHandler RuleBase.CustomFormatValidationMessage, AddressOf RuleBase_CustomFormatValidationMessage
        End Sub
        Private Sub RuleBase_CustomFormatValidationMessage(ByVal sender As Object, ByVal e As CustomFormatValidationMessageEventArgs)
            Dim rule As RuleBase = DirectCast(sender, RuleBase)
            If Not e.Handled AndAlso rule.Id = "MyRule" AndAlso TypeOf e.Object Is Employee Then
                Dim propertyCaption As String = rule.UsedProperties(0)
                Dim modelViewItem As IModelViewItem = View.Model.Items.FirstOrDefault(Function(x) x.Id = propertyCaption)
                propertyCaption = If(modelViewItem Is Nothing, propertyCaption, modelViewItem.Caption)
                e.ResultMessage = e.MessageFormat.Replace("{TargetPropertyName}", propertyCaption)
                e.Handled = True
            End If
        End Sub
        Protected Overrides Sub OnDeactivated()
            MyBase.OnDeactivated()
            RemoveHandler RuleBase.CustomFormatValidationMessage, AddressOf RuleBase_CustomFormatValidationMessage
        End Sub
    End Class
End Namespace

If you want to customize this message for all Views in the application, subscribe to this event in the ModuleBase.Setup method.