DbFirst/DbFirst.API/Middleware/ExceptionHandlingMiddleware.cs

using Microsoft.AspNetCore.Mvc;

namespace DbFirst.API.Middleware;

public class ExceptionHandlingMiddleware
{
    private readonly RequestDelegate _next;
    private readonly ILogger<ExceptionHandlingMiddleware> _logger;

    public ExceptionHandlingMiddleware(RequestDelegate next, ILogger<ExceptionHandlingMiddleware> logger)
    {
        _next = next;
        _logger = logger;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        try
        {
            await _next(context);
        }
        catch (InvalidOperationException ex)
        {
            _logger.LogWarning(ex, "Domain validation error");
            await WriteProblemAsync(context, StatusCodes.Status400BadRequest, "Eingabe ungültig", ex.Message);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Unhandled exception");
            await WriteProblemAsync(context, StatusCodes.Status500InternalServerError, "Serverfehler", ex.Message);
        }
    }

    private static async Task WriteProblemAsync(HttpContext context, int status, string title, string detail)
    {
        if (context.Response.HasStarted) return;

        context.Response.Clear();
        context.Response.StatusCode = status;
        context.Response.ContentType = "application/problem+json";

        var problem = new ProblemDetails
        {
            Type = $"https://tools.ietf.org/html/rfc9110#section-{(status == 400 ? "15.5.1" : "15.6.1")}",
            Title = title,
            Status = status,
            Detail = detail,
            Extensions = { ["traceId"] = context.TraceIdentifier }
        };

        await context.Response.WriteAsJsonAsync(problem);
    }
}