How can I define a custom attribute in ASP.NET Core Web API for endpoints and return an ObjectResult in it?

Question

I am creating an ASP.NET Core Web API project. I want to define an attribute (for example ExampleAttribute) and access the HttpContext in it and doing some action and finally return an ObjectResult if necessary, or continue.

I don't know if I am doing it right or not, but I want to define an attribute in this way:

    public class DeveloperTaskAttribute : Attribute
    {
        // using HttpContext and doing some action

        // I will returning BadRequest("") if necessary
        // or continue...
    }

And I'm trying to use this attribute on this endpoint:

    [HttpGet]
    [ExampleAttribute] // using attribute
    public IActionResult EndPoint1() 
    {      
        // doing some action in endpoint1
    }

How can I do this?

Thanks for any help.

Answer 1

You need to use ActionFilterAttribute Only:

Defining a new Attribute:

    public class TestAttribute : TypeFilterAttribute
        {
            public TestAttribute() : base(typeof(TestFilter))
            {
            }
    
            private class TestFilter : ActionFilterAttribute
            {
                private readonly MyDbContext _myDbContext;
    
                public TestFilter(MyDbContext myDbContext)
                {
                    _myDbContext = myDbContext;
                }
    
                public override void OnActionExecuting(ActionExecutingContext context)
                {
                    // Dont use async - await methods !
                    // Do something
                    var user= context.HttpContext.User    
                }
            }
    
    
        }

Note: You must use the word Attribute at the end of the name

And using in controller:

        [Test]
        [HttpGet]
        [Route("Example")]
        public async Task<IActionResult> ExampleMethod()
        {}

Documentation: https://www.andybutland.dev/2020/06/dependency-injection-in-aspnet-core-attributes.html