Skip to main content
.NET 6.0+

RuleBase.CustomFormatValidationMessage Event

Occurs when the validation result message is being formatted.

Namespace: DevExpress.Persistent.Validation

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


public static event EventHandler<CustomFormatValidationMessageEventArgs> CustomFormatValidationMessage

Event Data

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


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.

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() {
            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() {
            RuleBase.CustomFormatValidationMessage -= RuleBase_CustomFormatValidationMessage;

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

See Also