Search code examples
c#asp.netasp.net-core.net-5asp.net5

Handling error in .NET5 with a custom response class


I'm coming from a Java/Spring background and I'm trying to learn .NET 5.I'm working on a Web API,everything is Ok, but somehow I couldn't understand or make it work, I've tried some solutions found online, but as things changed over years I don't know if they don't work anymore or there is some better way to do this.

Basically, I want to handle errors within my .NET API.

My service has this code :

public Users execute(int id)
{
    var foundUser = this.userRepository.findById(id);
    if (foundUser == null)
    {
        throw new HttpException(HttpStatusCode.NotFound, "User not found");
    }
    return foundUser;
}

HttpException is a custom Exception I made so I can possess have the control over the Status Code

using System;
using System.Net;

namespace dotnetex.shared.Errors
{
    public class HttpException : Exception
    {

        public HttpStatusCode Status { get; set; }

        public HttpException(HttpStatusCode status, string msg) : base(msg)
        {
            Status = status;
        }
    }
}

My startup class has the Exception Handler pointing to my route :

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        app.UseExceptionHandler("/error"); // Add this
[...]

And my route looks like this

using System.Net;
using Microsoft.AspNetCore.Diagnostics;
using Microsoft.AspNetCore.Mvc;

namespace dotnetex.shared.Errors.Controller
{
    [ApiController]
    public class ErrorController : ControllerBase
    {
        [Route("/error")]
        public IActionResult Error()
        {
            var exception = HttpContext.Features.Get<IExceptionHandlerFeature>();
            HttpException error = (HttpException)exception.Error;
            var statusCode = (int)error.Status;
            return Problem(detail: error.Message, statusCode: statusCode);
        }
    }
}

For some reason, when I get the statusCode from "error" variable, I get my response broken, my Insomnia tells me Error: Transferred a partial file. Debbuging shows me the statusCode variable is set. When I set by code a number, things works as intended.

I've tried to call the Endpoint In Insomnia,Postman,Chrome Browser,CURL. All of them show errors

In the end,If it's possible.I want to return from this route a custom error object named API Error instead of the "Problem",like this one :

namespace dotnetex.shared.Errors
{
    public class APIError
    {
        private int status_code = 500;
        private string message = "";
        public APIError(int status_code, string message)
        {
            this.status_code = status_code;
            this.message = message;
        }
    }
}

The exception in console is :

fail: Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware[1]
      An unhandled exception has occurred while executing the request.
      dotnetex.shared.Errors.HttpException: User not found
         at dotnetex.modules.users.Services.Implementations.GetUserByIdService.GetUserByIdService.execute(Int32 id) in /home/matt/Source/net/dotnetexSl/dotnetex/modules/users/Services/Implementations/GetUserByIdService/GetUserByIdService.cs:line 23
         at modules.users.Services.UserServices.GetUserById(Int32 id) in /home/matt/Source/net/dotnetexSl/dotnetex/modules/users/Services/UserServices.cs:line 45
         at modules.users.Controllers.UsersControllers.getSingleUser(Int32 id) in /home/matt/Source/net/dotnetexSl/dotnetex/modules/users/Controllers/UsersControllers.cs:line 53
         at lambda_method1(Closure , Object , Object[] )
         at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.SyncObjectResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeActionMethodAsync()
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeNextActionFilterAsync()
      --- End of stack trace from previous location ---
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()
      --- End of stack trace from previous location ---
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
         at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
         at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)
warn: Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware[4]
      No exception handler was found, rethrowing original exception.
fail: Microsoft.AspNetCore.Server.Kestrel[13]
      Connection id "0HM6S5CSRT4C8", Request id "0HM6S5CSRT4C8:00000002": An unhandled exception was thrown by the application.
      dotnetex.shared.Errors.HttpException: User not found
         at dotnetex.modules.users.Services.Implementations.GetUserByIdService.GetUserByIdService.execute(Int32 id) in /home/matt/Source/net/dotnetexSl/dotnetex/modules/users/Services/Implementations/GetUserByIdService/GetUserByIdService.cs:line 23
         at modules.users.Services.UserServices.GetUserById(Int32 id) in /home/matt/Source/net/dotnetexSl/dotnetex/modules/users/Services/UserServices.cs:line 45
         at modules.users.Controllers.UsersControllers.getSingleUser(Int32 id) in /home/matt/Source/net/dotnetexSl/dotnetex/modules/users/Controllers/UsersControllers.cs:line 53
         at lambda_method1(Closure , Object , Object[] )
         at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.SyncObjectResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeActionMethodAsync()
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeNextActionFilterAsync()
      --- End of stack trace from previous location ---
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.InvokeInnerFilterAsync()
      --- End of stack trace from previous location ---
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
         at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
         at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
         at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)
         at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.HandleException(HttpContext context, ExceptionDispatchInfo edi)
         at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)
         at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)

So if you can help me finding a solution please, I would be grateful.

Thank you in advance!


Solution

  • ASP.NET Core 5 introduced breaking-change in handling the response status code NotFound 404. Use ExceptionHandlerOptions.AllowStatusCode404Response property.

    Fix UseExceptionHandler method like this:

    Startup.cs

     public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
     {
        app.UseExceptionHandler(
              new ExceptionHandlerOptions()
              {
                  AllowStatusCode404Response = true, // important!
                  ExceptionHandlingPath = "/error"                  
              }
          );      
      }