carparkvalidation/CarParkValidationAPI/Helpers/ErrorHandlerMiddleware.cs

using CarParkValidationAPI.Entities;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Generic;
using System.Net;
using System.Text.Json;
using System.Threading.Tasks;

namespace CarParkValidationAPI.Helpers
{
    public class ErrorHandlerMiddleware
    {
        private readonly RequestDelegate _next;
        private readonly ILogger<ErrorHandlerMiddleware> _logger;
        private readonly IHostEnvironment _env;

        public ErrorHandlerMiddleware(RequestDelegate next, 
            ILogger<ErrorHandlerMiddleware> logger, IHostEnvironment env)
        {
            _next = next;
            _logger = logger;
            _env = env;
        }
        public async Task Invoke(HttpContext context)
        {
            try
            {
                await _next(context);
            }
            catch (Exception ex)
            {
                var response = context.Response;
                response.ContentType = "application/json";
                _logger.LogError(ex, ex.Message);
                /*
                switch (ex)
                {
                    //  case Exception e:
                    //    // custom application error
                    //    response.StatusCode = (int)HttpStatusCode.BadRequest;
                    //    break;
                    case KeyNotFoundException:
                        // not found error
                        response.StatusCode = (int)HttpStatusCode.NotFound;
                        break;
                    default:
                        // unhandled error
                        response.StatusCode = (int)HttpStatusCode.InternalServerError;
                        break;
                } */
                response.StatusCode = ex switch
                {
                    //  case Exception e:
                    //    // custom application error
                    //    response.StatusCode = (int)HttpStatusCode.BadRequest;
                    //    break;
                    KeyNotFoundException => (int)HttpStatusCode.NotFound,// not found error
                    _ => (int)HttpStatusCode.InternalServerError,// unhandled error
                };
                //response.StatusCode = (int)HttpStatusCode.InternalServerError;
                var res = _env.IsDevelopment() ?
                    new ApiException(response.StatusCode, ex.Message, ex.StackTrace?.ToString())
                    : new ApiException(response.StatusCode, "Internal Server Error");

                var options = new JsonSerializerOptions { PropertyNamingPolicy = JsonNamingPolicy.CamelCase };
                var json = JsonSerializer.Serialize(res, options);
                await response.WriteAsync(json);
            }
        }
    }
}