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{
    "title": "Something went wrong",
    "status": 500,
    "detail": "Please contact support.",
    "instance": "/products/0"
}

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{
    "title": "Product not found",
    "status": 404,
    "detail": "No product with ID 42.",
    "instance": "/products/42"
}

12

public record Product(int Id, string Name);

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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 Invoke(HttpContext context)
    {
        try
        {
            await _next(context);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Unhandled exception occurred");

            var problem = new ProblemDetails
            {
                Title = "An unexpected error occurred.",
                Status = StatusCodes.Status500InternalServerError,
                Detail = "Please contact support.",
                Instance = context.Request.Path
            };

            context.Response.ContentType = "application/problem+json";
            context.Response.StatusCode = problem.Status.Value;

            var json = JsonSerializer.Serialize(problem);
            await context.Response.WriteAsync(json);
        }
    }
}

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using Microsoft.AspNetCore.Mvc;
using ProblemDetailsMinimalApi;

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

// Use custom error handling middleware
app.UseMiddleware<ExceptionHandlingMiddleware>();

// In-memory data for testing
var products = new List<Product>
{
    new Product(1, "Laptop"),
    new Product(2, "Phone"),
    new Product(3, "Keyboard")
};

// GET /products/{id}
app.MapGet("/products/{id:int}", (int id, HttpContext http) =>
{
    if (id <= 0)
        throw new ArgumentOutOfRangeException(nameof(id), "Product ID must be greater than zero.");

    var product = products.FirstOrDefault(p => p.Id == id);

    if (product is null)
    {
        var notFoundProblem = new ProblemDetails
        {
            Title = "Product not found",
            Status = StatusCodes.Status404NotFound,
            Detail = $"No product found with ID {id}.",
            Instance = http.Request.Path
        };

        return Results.Problem(
            title: notFoundProblem.Title,
            detail: notFoundProblem.Detail,
            statusCode: notFoundProblem.Status,
            instance: notFoundProblem.Instance
        );
    }

    return Results.Ok(product);
});

app.Run();

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public class CustomProblemDetails : ProblemDetails
{
    public string ErrorCode { get; set; } = default!;
}