IAsyncActionFilter is an interface in ASP.NET Core that allows developers to create custom action filters with asynchronous functionality. Action filters are used to execute code before or after the execution of an action method in an MVC (Model-View-Controller) application. By implementing IAsyncActionFilter, developers can perform tasks like logging, authentication, authorization, and response modification asynchronously, which can enhance the performance and scalability of the application.

Understanding IAsyncActionFilter

The IAsyncActionFilter interface is part of the Microsoft.AspNetCore.Mvc.Filters namespace. It defines a single method, OnActionExecutionAsync, which needs to be implemented when creating a custom asynchronous action filter. This method provides two parameters: ActionExecutingContext and ActionExecutionDelegate.

  • ActionExecutingContext: This parameter provides context about the current action being executed, including the action’s parameters, HTTP context, and the controller instance.
  • ActionExecutionDelegate: This parameter is a delegate that, when invoked, executes the action method and returns an ActionExecutedContext. The ActionExecutedContext contains information about the action’s result and any exceptions that might have occurred.

Implementing IAsyncActionFilter

Here is an example of how to implement a custom asynchronous action filter using IAsyncActionFilter:


using Microsoft.AspNetCore.Mvc.Filters;
using System.Threading.Tasks;

public class CustomAsyncActionFilter : IAsyncActionFilter
public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
// Code to execute before the action executes
var actionName = context.ActionDescriptor.DisplayName;
var startTime = DateTime.Now;

// Proceed to the next action/middleware in the pipeline
var resultContext = await next();

// Code to execute after the action executes
var endTime = DateTime.Now;
var duration = endTime - startTime;
var statusCode = resultContext.HttpContext.Response.StatusCode;

// Log action execution details
Console.WriteLine($"Action {actionName} executed in {duration.TotalMilliseconds} ms with status code {statusCode}");

Registering the Filter

To use the custom filter, you can register it japan phone number globally in the Startup.cs file or apply it to specific controllers or action methods.

  • Global Registration:

    public void ConfigureServices(IServiceCollection services)
    services.AddControllersWithViews(options =>
  • Controller/Action Registration:

    public class HomeController : Controller
    public IActionResult Index()
    return View();

Benefits of Using IAsyncActionFilter

  1. Improved Performance: Asynchronous Hong Kong phone number operations can improve the responsiveness and throughput of your application, especially when performing I/O-bound tasks.
  2. Enhanced Functionality: Custom filters allow for centralized and reusable logic that can be applied consistently across multiple actions and controllers.
  3. Separation of Concerns: Filters help in maintaining clean and manageable code by separating cross-cutting concerns like logging, error handling, and authorization from business logic.


Implementing IAsyncActionFilter in ASP.NET Core is a powerful way to add asynchronous, cross-cutting functionality to your MVC applications. By leveraging the asynchronous capabilities of this interface, developers can create more responsive and scalable applications while maintaining clean and maintainable code.

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