Exception Handling in ASP.NET MVC

Exception Handling in ASP.NET MVC

1. Overview Exception handling is an important aspect of building robust and reliable applications in ASP.NET MVC. It allows developers to gracefully handle and manage errors that may occur during the execution of an application. In ASP.NET MVC, exception handling can be implemented at various levels, including the global level, controller level, and action level.

2. Global Exception Handling Global exception handling allows developers to capture and handle exceptions that occur throughout the application. To implement global exception handling in ASP.NET MVC, you can create a custom exception filter by inheriting from the HandleErrorAttribute class. Here's an example:

csharp
public class CustomExceptionFilterAttribute : HandleErrorAttribute
{
    public override void OnException(ExceptionContext filterContext)
    {
        // Log the exception or perform any custom logic

        // Redirect to an error page or return a custom error response
        filterContext.Result = new ViewResult
        {
            ViewName = "Error",
            ViewData = new ViewDataDictionary(filterContext.Controller.ViewData)
        };
        
        filterContext.ExceptionHandled = true;
    }
}

To register the global exception filter, you can add it to the GlobalFilters collection in the Global.asax.cs file:

csharp
public class MvcApplication : System.Web.HttpApplication
{
    protected void Application_Start()
    {
        // Other application setup code
        
        // Register the global exception filter
        GlobalFilters.Filters.Add(new CustomExceptionFilterAttribute());
    }
}

3. Controller-level Exception Handling Controller-level exception handling allows you to handle exceptions specific to a controller or a group of related actions within a controller. You can override the OnException method in your controller to handle exceptions. Here's an example:

csharp
public class HomeController : Controller
{
    protected override void OnException(ExceptionContext filterContext)
    {
        // Log the exception or perform any custom logic

        // Redirect to an error page or return a custom error response
        filterContext.Result = new ViewResult
        {
            ViewName = "Error",
            ViewData = new ViewDataDictionary(filterContext.Controller.ViewData)
        };
        
        filterContext.ExceptionHandled = true;
    }
    
    public ActionResult Index()
    {
        // Action code
    }
}

4. Action-level Exception Handling Action-level exception handling allows you to handle exceptions specific to individual actions within a controller. You can use the HandleError attribute on an action method to handle exceptions. Here's an example:

csharp
public class HomeController : Controller
{
    [HandleError(View = "Error")]
    public ActionResult Index()
    {
        // Action code
    }
}

In this example, the HandleError attribute specifies the view to render in case of an exception.

5. Custom Error Pages To provide a better user experience, you can create custom error pages to display relevant information about the exception. You can create views such as "Error.cshtml" or "Error.aspx" to render the error page. Make sure to handle the appropriate HTTP status codes (e.g., 404 for page not found) in your error pages.

Conclusion Exception handling in ASP.NET MVC is crucial for handling errors and ensuring the smooth functioning of your application. By implementing global, controller-level, and action-level exception handling, you can handle and manage exceptions effectively. Additionally, creating custom error pages enhances the user experience by providing meaningful error information.

Note: The code examples provided are simplified for demonstration purposes. In a real-world scenario, you may need to add additional error logging, exception handling, and error recovery logic as per your application's requirements.