ExceptionService Class

A service that allows you to customize how XAF-related exceptions are handled.

Namespace: DevExpress.ExpressApp.Blazor.Services

Assembly: DevExpress.ExpressApp.Blazor.v26.1.dll

NuGet Package: DevExpress.ExpressApp.Blazor

Declaration

C#

public class ExceptionService :
    IExceptionHandlerService,
    IExceptionProviderService

VB.NET

Public Class ExceptionService
    Implements IExceptionHandlerService,
               IExceptionProviderService

Remarks

The ExceptionService exposes two methods:

ShouldHandleException(Exception)

Override this method to specify whether the ExceptionService should process an exception.

HandleException(Exception)

Override this method to process an exception, for example, to wrap it in a user-friendly exception (IUserFriendlyException) or customize the user-friendly text.

The following example displays a user-friendly exception message in your XAF Blazor UI application:

1. Add a controller:

   C#

   using DevExpress.ExpressApp;
   using DevExpress.ExpressApp.Actions;
   using System;
   
   namespace MySolution.Module.Controllers {
       public class MyCustomException : Exception {
       }
   
       public class TestExceptionController : ViewController {
           public TestExceptionController() {
               // When a user clicks this action, an exception is thrown.
               SimpleAction simpleAction = new SimpleAction(this, "Test Action", DevExpress.Persistent.Base.PredefinedCategory.Edit);
               simpleAction.Execute += SimpleAction_Execute;
           }
   
           private void SimpleAction_Execute(object sender, SimpleActionExecuteEventArgs e) {
               throw new MyCustomException();
           }
       }
   }
   

2. Add the MyCustomExceptionService service. Override the ShouldHandleException(Exception) method to specify that the service should process the MyCustomException exception, and override the HandleException(Exception) method to wrap this exception in a user-friendly exception:

   C#

   using DevExpress.Data.Exceptions;
   using DevExpress.ExpressApp.Blazor.Services;
   // ...
   public class MyCustomExceptionService : ExceptionService {
       public MyCustomExceptionService(ILogger<ExceptionService> logger) : base(logger) { }
       public override bool ShouldHandleException(Exception exception) {
           if(exception is MyCustomException) {
               return true;
           }
           else {
               return base.ShouldHandleException(exception);
           }
       }
       public override void HandleException(Exception exception) {
           Exception result = exception is MyCustomException ? new UserFriendlyException("My Test User Friendly Exception", exception) : exception;
           base.HandleException(result);
       }
   }
   

3. Register the MyCustomExceptionService service in the MySolution.Blazor.Server\Startup.cs file:

   C#

   // ...
   services.AddXaf<MySolutionBlazorApplication>(Configuration);
   // Register the service.
   services.AddScoped<IExceptionHandlerService, MyCustomExceptionService>();
   // ...
   

4. Run the application and click the Test Action button. The user-friendly exception is displayed in a toast notification.

   

For more information about the default error processing mechanism in XAF ASP.NET Core Blazor applications, refer to the following topic: Error Handling in XAF ASP.NET Core Blazor.

Inheritance

Object

ExceptionService