如何将.NetFramework 中的MessageHandler 转换为AspNet.Core

Question

I have below message handler to return some custom messages, and I am registering in WebAPIConfig.Register method in.NetFramework, but I am having troubles with.Net Core as it looks like message handlers are removed in .NET core, I am getting some issues converting it.

    public class WebApiCustomMessageHandler : DelegatingHandler
    {
        protected override async Task<HttpResponseMessage> SendAsync(
            HttpRequestMessage request, CancellationToken cancellationToken)
        {

            HttpResponseMessage response = await base.SendAsync(request, cancellationToken);

            if (response.StatusCode == HttpStatusCode.NotFound)
            {
                request.Properties.Remove(HttpPropertyKeys.NoRouteMatched);
                var errorResponse = request.CreateResponse(response.StatusCode, "resource not found.");
                return errorResponse;
            }

            return response;
        }
    }

registering in WebAPIConfig.Register method:

    public static void Register(HttpConfiguration config)
    {
      config.MessageHandlers.Add(new WebApiCustomMessageHandler());
    }

.NET Core implementation:

I have below code but it gives errors on creating response and and returning it.

        public class WebApiCustomMiddleware
        {
            private readonly RequestDelegate _next;
    
            public WebApiCustomMiddleware(RequestDelegate next)
            {
                _next = next;
            }
    
            public async Task Invoke(HttpContext context)
            {
                //process context.Request
    
                await _next(context);

                //process context.Response
    
                if (context.Response.StatusCode == HttpStatusCode.NotFound)
                {
                   context.Request.Properties.Remove(HttpPropertyKeys.NoRouteMatched);
                   var errorResponse = context.Request.CreateResponse(context.Response.StatusCode, "resource not found.");
                   return errorResponse;
                }
                 
               return response;
                  
            }
        }

How do I create response and return in .net core middleware it is giving errors as it doesn't have context.Request.Properties, context.Request.CreateResponse, and also what would be the return type?

context.Request.Properties.Remove(HttpPropertyKeys.NoRouteMatched);
var errorResponse = context.Request.CreateResponse(context.Response.StatusCode, "resource not found.");
return errorResponse;

Please suggest.

Answer 1

Below is the Implementation (thanks to @King King):

    public class WebApiCustomMiddleware
    {
        private readonly RequestDelegate _next;

        public WebApiCustomMiddleware(RequestDelegate next)
        {
            _next = next;
        }

        public async Task Invoke(HttpContext context)
        {
            //process context.Request
            //to do like validating api keys, request headers etc..

            await _next(context);

            //process context.Response
            if (context.Response.StatusCode == (int)HttpStatusCode.NotFound)
            {
                context.Response.ContentType = "application/json";
                await context.Response.WriteAsync(JsonConvert.SerializeObject(new
                {
                    statusCode = 404,
                    message = "resource not found"
                }));
            }
            else if(...)
            {}
        }
    }

And register in statup.cs

public void Configure(IApplicationBuilder app)
{
   app.UseMiddleware<WebApiCustomMiddleware>();
}