IExceptionHandler in ASP.NET Core 8

ASP.NET Core 8 introduces a new feature called IException handler. This feature provides a centralized way of handling exceptions in your application. Let's dive into what it is and how to use it.

What is an IException handler?

IException handler is an interface that allows you to handle exceptions consistently across your application. It provides a way to catch exceptions that occur in your code and handle them in a single place, rather than scattering error-handling code throughout your application.

How to use the IException handler?

To use the IException handler, you need to implement the interface in a class and register it in the Startup.cs file. Here's a simple example.

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddControllers();
        services.AddSingleton<IExceptionHandler, MyExceptionHandler>();
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        app.UseExceptionHandler("/error");
        app.UseRouting();
        
        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllers();
        });
    }
}

public class MyExceptionHandler : IExceptionHandler
{
    private readonly ILogger<MyExceptionHandler> _logger;

    public MyExceptionHandler(ILogger<MyExceptionHandler> logger)
    {
        _logger = logger;
    }

    public Task HandleExceptionAsync(ExceptionContext context)
    {
        var exception = context.Exception;
        
        // Log the exception
        _logger.LogError(exception, "An unexpected error occurred.");

        // Set the response
        context.Result = new ObjectResult("An error occurred while processing your request.")
        {
            StatusCode = StatusCodes.Status500InternalServerError
        };

        return Task.CompletedTask;
    }
}

In this example, My Exception handler is a class that implements the IException handler. It's registered as a singleton in the ConfigureServices method. The HandleExceptionAsync method is where you put your exception-handling logic.

In this code, we're injecting an `ILogger` into `MyExceptionHandler' to log exceptions. When an exception occurs, we log it and then set the HTTP response to a 500 status code with a generic error message. This way, we're not exposing any sensitive information about the error to the user. Remember, it's important to handle exceptions in a way that doesn't leak sensitive information. Always log the exception details server-side and only show the user what they need to know.

When an exception occurs, the handle Exception Async method will be called with an ExceptionContext object. This object contains information about the exception, including the exception itself, the HTTP context, and the action context.

Conclusion

IException handler is a powerful feature in ASP.NET Core 8 that helps you manage exceptions in a centralized way. It makes your code cleaner and easier to maintain by reducing the amount of error-handling code scattered throughout your application. Give it a try in your next ASP.NET Core project!

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