Kavita/API/Middleware/ExceptionMiddleware.cs

using System;
using System.Net;
using System.Text.Json;
using System.Threading.Tasks;
using API.Errors;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace API.Middleware
{
    public class ExceptionMiddleware
    {
        private readonly RequestDelegate _next;
        private readonly ILogger<ExceptionMiddleware> _logger;
        private readonly IHostEnvironment _env;


        public ExceptionMiddleware(RequestDelegate next, ILogger<ExceptionMiddleware> logger, IHostEnvironment env)
        {
            _next = next;
            _logger = logger;
            _env = env;
        }

        public async Task InvokeAsync(HttpContext context)
        {
            try
            {
                await _next(context); // downstream middlewares or http call
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "There was an exception");
                context.Response.ContentType = "application/json";
                context.Response.StatusCode = (int) HttpStatusCode.InternalServerError;

                var errorMessage = string.IsNullOrEmpty(ex.Message) ? "Internal Server Error" : ex.Message;

                var response = new ApiException(context.Response.StatusCode, errorMessage, ex.StackTrace);

                var options = new JsonSerializerOptions
                {
                    PropertyNamingPolicy =
                        JsonNamingPolicy.CamelCase
                };

                var json = JsonSerializer.Serialize(response, options);

                await context.Response.WriteAsync(json);

            }
        }
    }
}