ASP.NET Core 6: Standard responses, Swashbuckle filters, 400 handler, 500 handler

InvalidModelStateResponseHandler.cs

using Microsoft.AspNetCore.Mvc;

public static class InvalidModelStateResponseHandler
{
    public static IStandardResponse<IEnumerable<InvalidModelStateResponse>> Handle(ActionContext context)
    {
        ThrowIfNull(context, nameof(context));

        var hostEnvironment = context.HttpContext.RequestServices.GetService<IHostEnvironment>();
        IEnumerable<InvalidModelStateResponse> errors =
            context
                .ModelState.Values
                .SelectMany(a => a.Errors)
                .Select(
                    a =>
                        hostEnvironment.IsDevelopment()
                            ? new InvalidModelStateWithExceptionResponse(a.ErrorMessage, a.Exception)
                            : new InvalidModelStateResponse(a.ErrorMessage));

        return StandardResponse.BadRequest(errors, "Request model is invalid.");
    }
}

InvalidModelStateResponseHandler.Models.cs

public class InvalidModelStateResponse
{
    public InvalidModelStateResponse(string message)
    {
        Message = message;
    }

    public string Message { get; }
}

public sealed class InvalidModelStateWithExceptionResponse : InvalidModelStateResponse
{
    public InvalidModelStateWithExceptionResponse(string message, Exception? exception) : base(message)
    {
        Exception = CreateExceptionResponse(exception);
    }

    public InvalidModelStateExceptionResponse? Exception { get; }

    private static InvalidModelStateExceptionResponse? CreateExceptionResponse(Exception? exception) =>
        exception is not null
            ? new InvalidModelStateExceptionResponse(exception.Message, exception.StackTrace, CreateExceptionResponse(exception.InnerException))
            : null;
}

public sealed record InvalidModelStateExceptionResponse(string Message, string? StackTrace, InvalidModelStateExceptionResponse? InnerException);

IStandardResponse`1.cs

using Microsoft.AspNetCore.Mvc;

public interface IStandardResponse<out T> : IActionResult
{
    T? Data { get; }
    string? Message { get; }
}

NullableSchemaFilter.cs

using Microsoft.OpenApi.Models;
using Swashbuckle.AspNetCore.SwaggerGen;

public sealed class NullableSchemaFilter : ISchemaFilter
{
    public void Apply(OpenApiSchema schema, SchemaFilterContext context)
    {
        if (context.MemberInfo?.IsNonNullableReferenceType() != true)
        {
            return;
        }

        schema.Nullable = false;

        if (schema.Items is not null)
        {
            schema.Items.Nullable = false;
        }
    }
}

StandardResponse.cs

using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Primitives;

public static class StandardResponse
{
    // 100 Continue

    public static StandardResponse<T> Continue<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status100Continue, data, message, formattingDelegate);

    public static StandardResponse<object?> Continue(Action<ActionContext>? formattingDelegate = null) =>
        Continue<object?>(null, null, formattingDelegate);

    // 200 OK

    public static StandardResponse<T> Ok<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status200OK, data, message, formattingDelegate);

    public static StandardResponse<object?> Ok(Action<ActionContext>? formattingDelegate = null) =>
        Ok<object?>(null, null, formattingDelegate);

    // 201 Created

    public static StandardResponse<T> Created<T>(
        string location,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        new(
            StatusCodes.Status201Created,
            data,
            message,
            context =>
            {
                context.HttpContext.Response.Headers.Location = location;
                formattingDelegate?.Invoke(context);
            });

    public static StandardResponse<object?> Created(string location, Action<ActionContext>? formattingDelegate = null) =>
        Created<object?>(location, null, null, formattingDelegate);

    public static StandardResponse<T> Created<T>(Uri location, T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        Created(location.ToString(), data, message, formattingDelegate);

    public static StandardResponse<object?> Created(Uri location, Action<ActionContext>? formattingDelegate = null) =>
        Created<object?>(location, null, null, formattingDelegate);

    // 202 Accepted

    public static StandardResponse<T> Accepted<T>(
        string? location = null,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        new(
            StatusCodes.Status202Accepted,
            data,
            message,
            context =>
            {
                if (location is not null)
                {
                    context.HttpContext.Response.Headers.Location = location;
                }
                formattingDelegate?.Invoke(context);
            });

    public static StandardResponse<object?> Accepted(string? location = null, Action<ActionContext>? formattingDelegate = null) =>
        Accepted<object?>(location, null, null, formattingDelegate);

    public static StandardResponse<T> Accepted<T>(
        Uri? location = null,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        Accepted(location?.ToString(), data, message, formattingDelegate);

    public static StandardResponse<object?> Accepted(Uri? location = null, Action<ActionContext>? formattingDelegate = null) =>
        Accepted<object?>(location, null, null, formattingDelegate);

    // 204 No Content

    public static NoContentResponse NoContent(Action<ActionContext>? formattingDelegate = null) =>
        new(formattingDelegate);

    // 300 Multiple Choices

    public static StandardResponse<T> MultipleChoices<T>(
        string? location,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        new(
            StatusCodes.Status300MultipleChoices,
            data,
            message,
            context =>
            {
                context.HttpContext.Response.Headers.Location = location;
                formattingDelegate?.Invoke(context);
            });

    public static StandardResponse<object?> MultipleChoices(string? location, Action<ActionContext>? formattingDelegate = null) =>
        MultipleChoices<object?>(location, null, null, formattingDelegate);

    public static StandardResponse<T> MultipleChoices<T>(
        Uri? location,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        MultipleChoices(location?.ToString(), data, message, formattingDelegate);

    public static StandardResponse<object?> MultipleChoices(Uri? location, Action<ActionContext>? formattingDelegate = null) =>
        MultipleChoices<object?>(location, null, null, formattingDelegate);

    // 301 Moved Permanently

    public static StandardResponse<T> MovedPermanently<T>(
        string location,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        new(
            StatusCodes.Status301MovedPermanently,
            data,
            message,
            context =>
            {
                context.HttpContext.Response.Headers.Location = location;
                formattingDelegate?.Invoke(context);
            });

    public static StandardResponse<object?> MovedPermanently(string location, Action<ActionContext>? formattingDelegate = null) =>
        MovedPermanently<object?>(location, null, null, formattingDelegate);

    public static StandardResponse<T> MovedPermanently<T>(
        Uri location,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        MovedPermanently(location.ToString(), data, message, formattingDelegate);

    public static StandardResponse<object?> MovedPermanently(Uri location, Action<ActionContext>? formattingDelegate = null) =>
        MovedPermanently<object?>(location, null, null, formattingDelegate);

    // 302 Found

    public static StandardResponse<T> Found<T>(string location, T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(
            StatusCodes.Status302Found,
            data,
            message,
            context =>
            {
                context.HttpContext.Response.Headers.Location = location;
                formattingDelegate?.Invoke(context);
            });

    public static StandardResponse<object?> Found(string location, Action<ActionContext>? formattingDelegate = null) =>
        Found<object?>(location, null, null, formattingDelegate);

    public static StandardResponse<T> Found<T>(Uri location, T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        Found(location.ToString(), data, message, formattingDelegate);

    public static StandardResponse<object?> Found(Uri location, Action<ActionContext>? formattingDelegate = null) =>
        Found<object?>(location, null, null, formattingDelegate);

    // 303 See Other

    public static StandardResponse<T> SeeOther<T>(
        string location,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        new(
            StatusCodes.Status303SeeOther,
            data,
            message,
            context =>
            {
                context.HttpContext.Response.Headers.Location = location;
                formattingDelegate?.Invoke(context);
            });

    public static StandardResponse<object?> SeeOther(string location, Action<ActionContext>? formattingDelegate = null) =>
        SeeOther<object?>(location, null, null, formattingDelegate);

    public static StandardResponse<T> SeeOther<T>(Uri location, T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        SeeOther(location.ToString(), data, message, formattingDelegate);

    public static StandardResponse<object?> SeeOther(Uri location, Action<ActionContext>? formattingDelegate = null) =>
        SeeOther<object?>(location, null, null, formattingDelegate);

    // 304 Not Modified

    public static StandardResponse<T> NotModified<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status304NotModified, data, message, formattingDelegate);

    public static StandardResponse<object?> NotModified(Action<ActionContext>? formattingDelegate = null) =>
        NotModified<object?>(null, null, formattingDelegate);

    // 307 Temporary Redirect

    public static StandardResponse<T> TemporaryRedirect<T>(
        string location,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        new(
            StatusCodes.Status307TemporaryRedirect,
            data,
            message,
            context =>
            {
                context.HttpContext.Response.Headers.Location = location;
                formattingDelegate?.Invoke(context);
            });

    public static StandardResponse<object?> TemporaryRedirect(string location, Action<ActionContext>? formattingDelegate = null) =>
        TemporaryRedirect<object?>(location, null, null, formattingDelegate);

    public static StandardResponse<T> TemporaryRedirect<T>(
        Uri location,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        TemporaryRedirect(location.ToString(), data, message, formattingDelegate);

    public static StandardResponse<object?> TemporaryRedirect(Uri location, Action<ActionContext>? formattingDelegate = null) =>
        TemporaryRedirect<object?>(location, null, null, formattingDelegate);

    // 308 Permanent Redirect

    public static StandardResponse<T> PermanentRedirect<T>(
        string location,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        new(
            StatusCodes.Status308PermanentRedirect,
            data,
            message,
            context =>
            {
                context.HttpContext.Response.Headers.Location = location;
                formattingDelegate?.Invoke(context);
            });

    public static StandardResponse<object?> PermanentRedirect(string location, Action<ActionContext>? formattingDelegate = null) =>
        PermanentRedirect<object?>(location, null, null, formattingDelegate);

    public static StandardResponse<T> PermanentRedirect<T>(
        Uri location,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        PermanentRedirect(location.ToString(), data, message, formattingDelegate);

    public static StandardResponse<object?> PermanentRedirect(Uri location, Action<ActionContext>? formattingDelegate = null) =>
        PermanentRedirect<object?>(location, null, null, formattingDelegate);

    // 400 Bad Request

    public static StandardResponse<T> BadRequest<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status400BadRequest, data, message, formattingDelegate);

    public static StandardResponse<object?> BadRequest(Action<ActionContext>? formattingDelegate = null) =>
        BadRequest<object?>(null, null, formattingDelegate);

    // 401 Unauthorized

    public static StandardResponse<T> Unauthorized<T>(
        StringValues wwwAuthenticate,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        new(
            StatusCodes.Status401Unauthorized,
            data,
            message,
            context =>
            {
                context.HttpContext.Response.Headers.WWWAuthenticate = wwwAuthenticate;
                formattingDelegate?.Invoke(context);
            });

    public static StandardResponse<object?> Unauthorized(StringValues wwwAuthenticate, Action<ActionContext>? formattingDelegate = null) =>
        Unauthorized<object?>(wwwAuthenticate, formattingDelegate);

    // 403 Forbidden

    public static StandardResponse<T> Forbidden<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status403Forbidden, data, message, formattingDelegate);

    public static StandardResponse<object?> Forbidden(Action<ActionContext>? formattingDelegate = null) =>
        Forbidden<object?>(null, null, formattingDelegate);

    // 404 Not Found

    public static StandardResponse<T> NotFound<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status404NotFound, data, message, formattingDelegate);

    public static StandardResponse<object?> NotFound(Action<ActionContext>? formattingDelegate = null) =>
        NotFound<object?>(null, null, formattingDelegate);

    // 405 Not Found

    public static StandardResponse<T> MethodNotAllowed<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status405MethodNotAllowed, data, message, formattingDelegate);

    public static StandardResponse<object?> MethodNotAllowed(Action<ActionContext>? formattingDelegate = null) =>
        MethodNotAllowed<object?>(null, null, formattingDelegate);

    // 406 Not Acceptable

    public static StandardResponse<T> NotAcceptable<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status406NotAcceptable, data, message, formattingDelegate);

    public static StandardResponse<object?> NotAcceptable(Action<ActionContext>? formattingDelegate = null) =>
        NotAcceptable<object?>(null, null, formattingDelegate);

    // 407 Proxy Authentication Required

    public static StandardResponse<T> ProxyAuthenticationRequired<T>(
        StringValues proxyAuthenticate,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        new(
            StatusCodes.Status407ProxyAuthenticationRequired,
            data,
            message,
            context =>
            {
                context.HttpContext.Response.Headers.ProxyAuthenticate = proxyAuthenticate;
                formattingDelegate?.Invoke(context);
            });

    public static StandardResponse<object?> ProxyAuthenticationRequired(StringValues proxyAuthenticate, Action<ActionContext>? formattingDelegate = null) =>
        ProxyAuthenticationRequired<object?>(proxyAuthenticate, null, null, formattingDelegate);

    // 408 Request Timeout

    public static StandardResponse<T> RequestTimeout<T>(
        bool closeConnection = true,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        new(
            StatusCodes.Status408RequestTimeout,
            data,
            message,
            context =>
            {
                if (closeConnection)
                {
                    context.HttpContext.Response.Headers.Connection = "close";
                }
                formattingDelegate?.Invoke(context);
            });

    public static StandardResponse<object?> RequestTimeout(bool closeConnection = true, Action<ActionContext>? formattingDelegate = null) =>
        RequestTimeout<object?>(closeConnection, null, null, formattingDelegate);

    // 409 Conflict

    public static StandardResponse<T> Conflict<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status409Conflict, data, message, formattingDelegate);

    public static StandardResponse<object?> Conflict(Action<ActionContext>? formattingDelegate = null) =>
        Conflict<object?>(null, null, formattingDelegate);

    // 410 Gone

    public static StandardResponse<T> Gone<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status410Gone, data, message, formattingDelegate);

    public static StandardResponse<object?> Gone(Action<ActionContext>? formattingDelegate = null) =>
        Gone<object?>(null, null, formattingDelegate);

    // 411 Length Required

    public static StandardResponse<T> LengthRequired<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status411LengthRequired, data, message, formattingDelegate);

    public static StandardResponse<object?> LengthRequired(Action<ActionContext>? formattingDelegate = null) =>
        LengthRequired<object?>(null, null, formattingDelegate);

    // 412 Preconditon Failed

    public static StandardResponse<T> PreconditionFailed<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status412PreconditionFailed, data, message, formattingDelegate);

    public static StandardResponse<object?> PreconditionFailed(Action<ActionContext>? formattingDelegate = null) =>
        PreconditionFailed<object?>(null, null, formattingDelegate);

    // 413 Payload Too Large

    public static StandardResponse<T> PayloadTooLarge<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status413PayloadTooLarge, data, message, formattingDelegate);

    public static StandardResponse<object?> PayloadTooLarge(Action<ActionContext>? formattingDelegate = null) =>
        PayloadTooLarge<object?>(null, null, formattingDelegate);

    // 414 Payload Too Large

    public static StandardResponse<T> UriTooLong<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status414UriTooLong, data, message, formattingDelegate);

    public static StandardResponse<object?> UriTooLong(Action<ActionContext>? formattingDelegate = null) =>
        UriTooLong<object?>(null, null, formattingDelegate);

    // 415 Unsupported Media Type

    public static StandardResponse<T> UnsupportedMediaType<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status415UnsupportedMediaType, data, message, formattingDelegate);

    public static StandardResponse<object?> UnsupportedMediaType(Action<ActionContext>? formattingDelegate = null) =>
        UnsupportedMediaType<object?>(null, null, formattingDelegate);

    // 416 Range Not Satisfiable

    public static StandardResponse<T> RangeNotSatisfiable<T>(
        StringValues contentRange,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        new(
            StatusCodes.Status416RangeNotSatisfiable,
            data,
            message,
            context =>
            {
                context.HttpContext.Response.Headers.ContentRange = contentRange;
                formattingDelegate?.Invoke(context);
            });

    public static StandardResponse<object?> RangeNotSatisfiable(StringValues contentRange, Action<ActionContext>? formattingDelegate = null) =>
        RangeNotSatisfiable<object?>(contentRange, null, null, formattingDelegate);

    // 417 Expectation Failed

    public static StandardResponse<T> ExpectationFailed<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status417ExpectationFailed, data, message, formattingDelegate);

    public static StandardResponse<object?> ExpectationFailed(Action<ActionContext>? formattingDelegate = null) =>
        ExpectationFailed<object?>(null, null, formattingDelegate);

    // 418 I'm a Teapot

    public static StandardResponse<T> ImATeapot<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status418ImATeapot, data, message, formattingDelegate);

    public static StandardResponse<object?> ImATeapot(Action<ActionContext>? formattingDelegate = null) =>
        ImATeapot<object?>(null, null, formattingDelegate);

    // 428 Precondition Required

    public static StandardResponse<T> PreconditionRequired<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status428PreconditionRequired, data, message, formattingDelegate);

    public static StandardResponse<object?> PreconditionRequired(Action<ActionContext>? formattingDelegate = null) =>
        PreconditionRequired<object?>(null, null, formattingDelegate);

    // 431 Request Header Fields Too Large

    public static StandardResponse<T> RequestHeaderFieldsTooLarge<T>(
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status431RequestHeaderFieldsTooLarge, data, message, formattingDelegate);

    public static StandardResponse<object?> RequestHeaderFieldsTooLarge(Action<ActionContext>? formattingDelegate = null) =>
        RequestHeaderFieldsTooLarge<object?>(null, null, formattingDelegate);

    // 451 Unavailable for Legal Reasons

    public static StandardResponse<T> UnavailableForLegalReasons<T>(
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        new(
            StatusCodes.Status451UnavailableForLegalReasons,
            data,
            message,
            formattingDelegate);

    public static StandardResponse<object?> UnavailableForLegalReasons(Action<ActionContext>? formattingDelegate = null) =>
        UnavailableForLegalReasons<object?>(null, null, formattingDelegate);

    // 500 Internal Server Error

    public static StandardResponse<T> InternalServerError<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status500InternalServerError, data, message, formattingDelegate);

    public static StandardResponse<object?> InternalServerError(Action<ActionContext>? formattingDelegate = null) =>
        InternalServerError<object?>(null, null, formattingDelegate);

    // 501 Not Implemented

    public static StandardResponse<T> NotImplemented<T>(
        StringValues? retryAfter = null,
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        new(
            StatusCodes.Status501NotImplemented,
            data,
            message,
            context =>
            {
                if (retryAfter is not null)
                {
                    context.HttpContext.Response.Headers.RetryAfter = retryAfter.Value;
                }
                formattingDelegate?.Invoke(context);
            });

    public static StandardResponse<object?> NotImplemented(StringValues? retryAfter = null, Action<ActionContext>? formattingDelegate = null) =>
        NotImplemented<object?>(retryAfter, null, null, formattingDelegate);

    // 502 Bad Gateway

    public static StandardResponse<T> BadGateway<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status502BadGateway, data, message, formattingDelegate);

    public static StandardResponse<object?> BadGateway(Action<ActionContext>? formattingDelegate = null) =>
        BadGateway<object?>(null, null, formattingDelegate);

    // 503 Service Unavailable

    public static StandardResponse<T> ServiceUnavailable<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status503ServiceUnavailable, data, message, formattingDelegate);

    public static StandardResponse<object?> ServiceUnavailable(Action<ActionContext>? formattingDelegate = null) =>
        ServiceUnavailable<object?>(null, null, formattingDelegate);

    // 504 Gateway Timeout

    public static StandardResponse<T> GatewayTimeout<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status504GatewayTimeout, data, message, formattingDelegate);

    public static StandardResponse<object?> GatewayTimeout(Action<ActionContext>? formattingDelegate = null) =>
        GatewayTimeout<object?>(null, null, formattingDelegate);

    // 505 HTTP Version Not Supported

    public static StandardResponse<T> HttpVersionNotSupported<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status505HttpVersionNotsupported, data, message, formattingDelegate);

    public static StandardResponse<object?> HttpVersionNotSupported(Action<ActionContext>? formattingDelegate = null) =>
        HttpVersionNotSupported<object?>(null, null, formattingDelegate);

    // 506 Variant Also Negotiates

    public static StandardResponse<T> VariantAlsoNegotiates<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status506VariantAlsoNegotiates, data, message, formattingDelegate);

    public static StandardResponse<object?> VariantAlsoNegotiates(Action<ActionContext>? formattingDelegate = null) =>
        VariantAlsoNegotiates<object?>(null, null, formattingDelegate);

    // 510 Not Extended

    public static StandardResponse<T> NotExtended<T>(T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status510NotExtended, data, message, formattingDelegate);

    public static StandardResponse<object?> NotExtended(Action<ActionContext>? formattingDelegate = null) =>
        NotExtended<object?>(null, null, formattingDelegate);

    // 511 Network Authentication Required

    public static StandardResponse<T> NetworkAuthenticationRequired<T>(
        T? data = default,
        string? message = null,
        Action<ActionContext>? formattingDelegate = null) =>
        new(StatusCodes.Status511NetworkAuthenticationRequired, data, message, formattingDelegate);

    public static StandardResponse<object?> NetworkAuthenticationRequired(Action<ActionContext>? formattingDelegate = null) =>
        NetworkAuthenticationRequired<object?>(null, null, formattingDelegate);
}

StandardResponse`1.cs

using Microsoft.AspNetCore.Mvc;

public sealed class StandardResponse<T> : ObjectResult, IStandardResponse<T>
{
    private readonly Action<ActionContext>? _formattingDelegate;

    public StandardResponse(int statusCode, T? data = default, string? message = null, Action<ActionContext>? formattingDelegate = null)
        : base(
            new
            {
                Data = data,
                Message = message
            })
    {
        StatusCode = statusCode;
        Data = data;
        Message = message;
        _formattingDelegate = formattingDelegate;
    }

    public T? Data { get; }
    public string? Message { get; }

    public override void OnFormatting(ActionContext context)
    {
        ThrowIfNull(context, nameof(context));

        if (StatusCode is not null)
        {
            context.HttpContext.Response.StatusCode = StatusCode.Value;
        }

        _formattingDelegate?.Invoke(context);

        base.OnFormatting(context);
    }
}

StandardResponseFilter.cs

// Copyright (c) Smoky Peak Software, LLC.

using Microsoft.OpenApi.Models;
using Swashbuckle.AspNetCore.SwaggerGen;

public sealed class StandardResponseFilter : ISchemaFilter
{
    public void Apply(OpenApiSchema schema, SchemaFilterContext context)
    {
        Type type = context.Type;

        if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(IStandardResponse<>))
        {
            schema.Title = $"IStandardResponse<{type.GetGenericArguments()[0].Name}>";
        }
    }
}

UnhandledExceptionHandler.cs

using Microsoft.AspNetCore.Diagnostics;
using Microsoft.AspNetCore.Http.Json;
using Microsoft.Extensions.Options;

public static class UnhandledExceptionHandler
{
    public static async Task Handle(HttpContext context)
    {
        ThrowIfNull(context, nameof(context));

        var hostEnvironment = context.RequestServices.GetService<IHostEnvironment>();
        var jsonOptions = context.RequestServices.GetService<IOptions<JsonOptions>>();
        var exceptionHandlerFeature = context.Features.Get<IExceptionHandlerFeature>();

        AssertNotNull(hostEnvironment);
        AssertNotNull(jsonOptions);
        AssertNotNull(exceptionHandlerFeature);

        static UnhandledExceptionResponse? CreateUnhandledExceptionResponse(Exception? exception) =>
            exception is not null
                ? new UnhandledExceptionResponse(exception.Message, exception.StackTrace, CreateUnhandledExceptionResponse(exception.InnerException))
                : null;

        StandardResponse<UnhandledExceptionResponse> response =
            StandardResponse.InternalServerError(
                hostEnvironment.IsDevelopment()
                    ? CreateUnhandledExceptionResponse(exceptionHandlerFeature.Error)
                    : null,
                "An unhandled exception has occurred.");

        context.Response.StatusCode = response.StatusCode ?? StatusCodes.Status500InternalServerError;

        await context.Response.WriteAsJsonAsync(response.Value, jsonOptions.Value.SerializerOptions);
    }
}

UnhandledExceptionHandler.Models.cs

public sealed record UnhandledExceptionResponse(string Message, string? StackTrace, UnhandledExceptionResponse? InnerException);