WebAPi - 统一来自ApiController和OAuthAuthorizationServerProvider的错误消息格式

Question

在我的WebAPI项目中,我Owin.Security.OAuth用来添加JWT身份验证.GrantResourceOwnerCredentials我的OAuthProvider 内部使用以下行设置错误:

context.SetError("invalid_grant", "Account locked.");

这将返回给客户:

{
  "error": "invalid_grant",
  "error_description": "Account locked."
}

在用户获得身份验证并且他尝试向我的某个控制器执行"正常"请求后,当模型无效时,他会得到以下响应(使用FluentValidation):

{
  "message": "The request is invalid.",
  "modelState": {
    "client.Email": [
      "Email is not valid."
    ],
    "client.Password": [
      "Password is required."
    ]
  }
}

这两个请求都在返回400 Bad Request,但有时您必须查找error_description字段,有时候还要查找message

我能够创建自定义响应消息,但这仅适用于我返回的结果.

我的问题是:是否有可能取代message与error响应由返回ModelValidatorProviders,并在其他地方？

我读过ExceptionFilterAttribute但我不知道这是不是一个好的起点.FluentValidation应该不是问题,因为它只是添加错误ModelState.

编辑:
我正在尝试解决的下一件事是WebApi中返回的数据中的命名约定不一致 - 当OAuthProvider我们返回错误error_details时,但是当我们返回BadRequest时ModelState(从ApiController)返回错误modelState.正如你可以看到第一次使用snake_case和第二次camelCase.

Answer 1

更新的答案(使用中间件)

由于Web API原始委托处理程序的想法意味着它不像OAuth中间件那样在管道中足够早,因此需要创建自定义中间件...

public static class ErrorMessageFormatter {

    public static IAppBuilder UseCommonErrorResponse(this IAppBuilder app) {
        app.Use<JsonErrorFormatter>();
        return app;
    }

    public class JsonErrorFormatter : OwinMiddleware {
        public JsonErrorFormatter(OwinMiddleware next)
            : base(next) {
        }

        public override async Task Invoke(IOwinContext context) {
            var owinRequest = context.Request;
            var owinResponse = context.Response;
            //buffer the response stream for later
            var owinResponseStream = owinResponse.Body;
            //buffer the response stream in order to intercept downstream writes
            using (var responseBuffer = new MemoryStream()) {
                //assign the buffer to the resonse body
                owinResponse.Body = responseBuffer;

                await Next.Invoke(context);

                //reset body
                owinResponse.Body = owinResponseStream;

                if (responseBuffer.CanSeek && responseBuffer.Length > 0 && responseBuffer.Position > 0) {
                    //reset buffer to read its content
                    responseBuffer.Seek(0, SeekOrigin.Begin);
                }

                if (!IsSuccessStatusCode(owinResponse.StatusCode) && responseBuffer.Length > 0) {
                    //NOTE: perform your own content negotiation if desired but for this, using JSON
                    var body = await CreateCommonApiResponse(owinResponse, responseBuffer);

                    var content = JsonConvert.SerializeObject(body);

                    var mediaType = MediaTypeHeaderValue.Parse(owinResponse.ContentType);
                    using (var customResponseBody = new StringContent(content, Encoding.UTF8, mediaType.MediaType)) {
                        var customResponseStream = await customResponseBody.ReadAsStreamAsync();
                        await customResponseStream.CopyToAsync(owinResponseStream, (int)customResponseStream.Length, owinRequest.CallCancelled);
                        owinResponse.ContentLength = customResponseStream.Length;
                    }
                } else {
                    //copy buffer to response stream this will push it down to client
                    await responseBuffer.CopyToAsync(owinResponseStream, (int)responseBuffer.Length, owinRequest.CallCancelled);
                    owinResponse.ContentLength = responseBuffer.Length;
                }
            }
        }

        async Task<object> CreateCommonApiResponse(IOwinResponse response, Stream stream) {

            var json = await new StreamReader(stream).ReadToEndAsync();

            var statusCode = ((HttpStatusCode)response.StatusCode).ToString();
            var responseReason = response.ReasonPhrase ?? statusCode;

            //Is this a HttpError
            var httpError = JsonConvert.DeserializeObject<HttpError>(json);
            if (httpError != null) {
                return new {
                    error = httpError.Message ?? responseReason,
                    error_description = (object)httpError.MessageDetail
                    ?? (object)httpError.ModelState
                    ?? (object)httpError.ExceptionMessage
                };
            }

            //Is this an OAuth Error
            var oAuthError = Newtonsoft.Json.Linq.JObject.Parse(json);
            if (oAuthError["error"] != null && oAuthError["error_description"] != null) {
                dynamic obj = oAuthError;
                return new {
                    error = (string)obj.error,
                    error_description = (object)obj.error_description
                };
            }

            //Is this some other unknown error (Just wrap in common model)
            var error = JsonConvert.DeserializeObject(json);
            return new {
                error = responseReason,
                error_description = error
            };
        }

        bool IsSuccessStatusCode(int statusCode) {
            return statusCode >= 200 && statusCode <= 299;
        }
    }
}

...并在添加身份验证中间件和Web api处理程序之前在管道中注册.

public class Startup {
    public void Configuration(IAppBuilder app) {

        app.UseResponseEncrypterMiddleware();

        app.UseRequestLogger();

        //...(after logging middle ware)
        app.UseCommonErrorResponse();

        //... (before auth middle ware)

        //...code removed for brevity
    }
} 

这个例子只是一个基本的开始.它应该足够简单,能够扩展这个起点.

虽然在此示例中,常见模型看起来像从OAuthProvider返回的内容,但可以使用任何常见的对象模型.

通过一些内存单元测试对其进行测试,并通过TDD能够使其正常工作.

[TestClass]
public class UnifiedErrorMessageTests {
    [TestMethod]
    public async Task _OWIN_Response_Should_Pass_When_Ok() {
        //Arrange
        var message = "\"Hello World\"";
        var expectedResponse = "\"I am working\"";

        using (var server = TestServer.Create<WebApiTestStartup>()) {
            var client = server.HttpClient;
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            var content = new StringContent(message, Encoding.UTF8, "application/json");

            //Act
            var response = await client.PostAsync("/api/Foo", content);

            //Assert
            Assert.IsTrue(response.IsSuccessStatusCode);

            var result = await response.Content.ReadAsStringAsync();

            Assert.AreEqual(expectedResponse, result);
        }
    }

    [TestMethod]
    public async Task _OWIN_Response_Should_Be_Unified_When_BadRequest() {
        //Arrange
        var expectedResponse = "invalid_grant";

        using (var server = TestServer.Create<WebApiTestStartup>()) {
            var client = server.HttpClient;
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            var content = new StringContent(expectedResponse, Encoding.UTF8, "application/json");

            //Act
            var response = await client.PostAsync("/api/Foo", content);

            //Assert
            Assert.IsFalse(response.IsSuccessStatusCode);

            var result = await response.Content.ReadAsAsync<dynamic>();

            Assert.AreEqual(expectedResponse, (string)result.error_description);
        }
    }

    [TestMethod]
    public async Task _OWIN_Response_Should_Be_Unified_When_MethodNotAllowed() {
        //Arrange
        var expectedResponse = "Method Not Allowed";

        using (var server = TestServer.Create<WebApiTestStartup>()) {
            var client = server.HttpClient;
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            //Act
            var response = await client.GetAsync("/api/Foo");

            //Assert
            Assert.IsFalse(response.IsSuccessStatusCode);

            var result = await response.Content.ReadAsAsync<dynamic>();

            Assert.AreEqual(expectedResponse, (string)result.error);
        }
    }

    [TestMethod]
    public async Task _OWIN_Response_Should_Be_Unified_When_NotFound() {
        //Arrange
        var expectedResponse = "Not Found";

        using (var server = TestServer.Create<WebApiTestStartup>()) {
            var client = server.HttpClient;
            client.DefaultRequestHeaders.Accept.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

            //Act
            var response = await client.GetAsync("/api/Bar");

            //Assert
            Assert.IsFalse(response.IsSuccessStatusCode);

            var result = await response.Content.ReadAsAsync<dynamic>();

            Assert.AreEqual(expectedResponse, (string)result.error);
        }
    }

    public class WebApiTestStartup {
        public void Configuration(IAppBuilder app) {

            app.UseCommonErrorMessageMiddleware();

            var config = new HttpConfiguration();
            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );

            app.UseWebApi(config);
        }
    }

    public class FooController : ApiController {
        public FooController() {

        }
        [HttpPost]
        public IHttpActionResult Bar([FromBody]string input) {
            if (input == "Hello World")
                return Ok("I am working");

            return BadRequest("invalid_grant");
        }
    }
}

原始答案(使用DelegatingHandler)

考虑使用 DelegatingHandler

引自在线发现的文章.

委派处理程序对于横切问题非常有用.它们挂钩到请求 - 响应管道的非常早期和非常晚的阶段,使它们成为在将响应发送回客户端之前进行操作的理想选择.

此示例是针对HttpError响应的统一错误消息的简化尝试

public class HttpErrorHandler : DelegatingHandler {

    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) {
        var response = await base.SendAsync(request, cancellationToken);

        return NormalizeResponse(request, response);
    }

    private HttpResponseMessage NormalizeResponse(HttpRequestMessage request, HttpResponseMessage response) {
        object content;
        if (!response.IsSuccessStatusCode && response.TryGetContentValue(out content)) {

            var error = content as HttpError;
            if (error != null) {

                var unifiedModel = new {
                    error = error.Message,
                    error_description = (object)error.MessageDetail ?? error.ModelState
                };

                var newResponse = request.CreateResponse(response.StatusCode, unifiedModel);

                foreach (var header in response.Headers) {
                    newResponse.Headers.Add(header.Key, header.Value);
                }

                return newResponse;
            }

        }
        return response;
    }
}

虽然这个示例非常基础,但扩展它以满足您的自定义需求是微不足道的.

现在只需将处理程序添加到管道即可

public static class WebApiConfig {
    public static void Register(HttpConfiguration config) {

        config.MessageHandlers.Add(new HttpErrorHandler());

        // Other code not shown...
    }
}

消息处理程序的调用顺序与它们在MessageHandlers集合中的显示顺序相同 .因为它们是嵌套的,所以响应消息以另一个方向传播.也就是说,最后一个处理程序是第一个获取响应消息的处理程序.

源:ASP.NET Web API中的HTTP消息处理程序

Answer 2

是否可以用 ModelValidatorProviders 返回的响应错误替换消息

我们可以使用重载的SetError来做到这一点，否则，用消息替换错误。

BaseValidatingContext<TOptions>.SetError Method (String)

将此上下文标记为未经应用程序验证，并分配各种错误信息属性。调用的结果是 HasError 变为 true，IsValidated 变为 false。

string msg = "{\"message\": \"Account locked.\"}";
context.SetError(msg); 
Response.StatusCode = 400;
context.Response.Write(msg);