如何覆盖 WebAPI 中的所有标准错误页面 [英] How to override all standard error pages in WebAPI
问题描述
我漂亮的 REST 网络服务运行良好.除非我访问像 ~/ 这样的页面，它返回默认的 IIS 403 禁止页面(即使使用 Fiddler 并仅指定 Accept: application/json).我只想要 JSON 或 XML 错误.有没有办法用自定义异常处理程序覆盖所有异常?或处理所有未知请求的默认控制器?处理这个问题的最简单、最正确(如果不同)的方法是什么，以便客户端只需要解析 REST API 友好的 XML 数据报或 JSON blob?
My beautiful REST webservice works great. Except if I visit pages like ~/, which returns the default IIS 403 Forbidden page (even using Fiddler and specifying only Accept: application/json). I want nothing but JSON or XML errors. Is there a way to override ALL exceptions with a custom exception handler? or a default controller to handle all unknown requests? What's the simplest, and the most correct (if different), way to handle this so that clients need only parse REST API-friendly XML datagrams or JSON blobs?
示例请求:
GET http://localhost:7414/ HTTP/1.1
User-Agent: Fiddler
Host: localhost:7414
Accept: application/json, text/json, text/xml
响应:(我不喜欢，请注意 text/html 不是接受的响应类型之一)
Response: (that I don't like, notice that text/html wasn't one of the accepted response types)
HTTP/1.1 403 Forbidden
Cache-Control: private
Content-Type: text/html; charset=utf-8
Server: Microsoft-IIS/8.0
X-SourceFiles: =?UTF-8?B?QzpcaWNhcm9sXENoYXJpdHlMb2dpYy5pQ2Fyb2wuQXBp?=
X-Powered-By: ASP.NET
Date: Fri, 25 Jan 2013 21:06:21 GMT
Content-Length: 5396
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>IIS 8.0 Detailed Error - 403.14 - Forbidden</title>
<style type="text/css">
<!--
...
响应(我更喜欢):
HTTP/1.1 403 Forbidden
Cache-Control: private
Content-Type: application/json; charset=utf-8
Date: ...
Content-Length: ....
{
"error":"forbidden",
"status":403,
"error_description":"Directory listing not allowed."
}
推荐答案
Edit 1/26/14: Microsoft 刚刚添加了全局错误处理" 到最新的 WebAPI 2.1 更新.
Edit 1/26/14: Microsoft just added "Global Error Handling" to the latest WebAPI 2.1 update.
好的，我想我明白了.它有几个部分.
Ok, I think I've got it. There's a few parts to it.
首先:为您的错误创建一个控制器.我根据 HTTP 错误代码命名了我的操作.
First: Create a controller for your errors. I named my actions according to the HTTP error codes.
public class ErrorController : ApiController {
[AllowAnonymous]
[ActionName("Get")]
public HttpResponseMessage Get() {
return Request.CreateErrorInfoResponse(HttpStatusCode.InternalServerError, title: "Unknown Error");
}
[AllowAnonymous]
[ActionName("404")]
[HttpGet]
public HttpResponseMessage Status404() {
return Request.CreateErrorInfoResponse(HttpStatusCode.NotFound, description: "No resource matches the URL specified.");
}
[AllowAnonymous]
[ActionName("400")]
[HttpGet]
public HttpResponseMessage Status400() {
return Request.CreateErrorInfoResponse(HttpStatusCode.BadRequest);
}
[AllowAnonymous]
[ActionName("500")]
[HttpGet]
public HttpResponseMessage Status500() {
return Request.CreateErrorInfoResponse(HttpStatusCode.InternalServerError);
}
}
接下来，我创建了一个 GenericExceptionFilterAttribute 来检查是否填充了 HttpActionExecutedContext.Exception 以及响应是否仍然为空.如果两种情况都为真，那么它会生成一个响应.
Next, I created a GenericExceptionFilterAttribute that checks to see if the HttpActionExecutedContext.Exception is populated and if the response is still empty. If both cases are true, then it generates a response.
public class GenericExceptionFilterAttribute : ExceptionFilterAttribute {
public GenericExceptionFilterAttribute()
: base() {
DefaultHandler = (context, ex) => context.Request.CreateErrorInfoResponse(System.Net.HttpStatusCode.InternalServerError, "Internal Server Error", "An unepected error occoured on the server.", exception: ex);
}
readonly Dictionary<Type, Func<HttpActionExecutedContext, Exception, HttpResponseMessage>> exceptionHandlers = new Dictionary<Type, Func<HttpActionExecutedContext, Exception, HttpResponseMessage>>();
public Func<HttpActionExecutedContext, Exception, HttpResponseMessage> DefaultHandler { get; set; }
public void AddExceptionHandler<T>(Func<HttpActionExecutedContext, Exception, HttpResponseMessage> handler) where T : Exception {
exceptionHandlers.Add(typeof(T), handler);
}
public override void OnException(HttpActionExecutedContext context) {
if (context.Exception == null) return;
try {
var exType = context.Exception.GetType();
if (exceptionHandlers.ContainsKey(exType))
context.Response = exceptionHandlers[exType](context, context.Exception);
if(context.Response == null && DefaultHandler != null)
context.Response = DefaultHandler(context, context.Exception);
}
catch (Exception ex) {
context.Response = context.Request.CreateErrorInfoResponse(HttpStatusCode.InternalServerError, description: "Error while building the exception response.", exception: ex);
}
}
}
就我而言，我使用了一个通用处理程序，我可以注册对每个主要异常类型的支持，并将这些异常类型中的每一个映射到特定的 HTTP 响应代码.现在在您的 global.asax.cs 中全局注册您的异常类型和处理程序:
In my case, I went with a single generic handler that I could register support for each of the main exception types and map each of those exception types to specific HTTP response codes. Now register your exception types and handlers this filter globally in your global.asax.cs:
// These filters override the default ASP.NET exception handling to create REST-Friendly error responses.
var exceptionFormatter = new GenericExceptionFilterAttribute();
exceptionFormatter.AddExceptionHandler<NotImplementedException>((context, ex) => context.Request.CreateErrorInfoResponse(System.Net.HttpStatusCode.InternalServerError, "Not Implemented", "This method has not yet been implemented. Please try your request again at a later date.", exception: ex));
exceptionFormatter.AddExceptionHandler<ArgumentException>((context, ex) => context.Request.CreateErrorInfoResponse(System.Net.HttpStatusCode.BadRequest, exception: ex));
exceptionFormatter.AddExceptionHandler<ArgumentNullException>((context, ex) => context.Request.CreateErrorInfoResponse(System.Net.HttpStatusCode.BadRequest, exception: ex));
exceptionFormatter.AddExceptionHandler<ArgumentOutOfRangeException>((context, ex) => context.Request.CreateErrorInfoResponse(System.Net.HttpStatusCode.BadRequest, exception: ex));
exceptionFormatter.AddExceptionHandler<FormatException>((context, ex) => context.Request.CreateErrorInfoResponse(System.Net.HttpStatusCode.BadRequest, exception: ex));
exceptionFormatter.AddExceptionHandler<NotSupportedException>((context, ex) => context.Request.CreateErrorInfoResponse(System.Net.HttpStatusCode.BadRequest, "Not Supported", exception: ex));
exceptionFormatter.AddExceptionHandler<InvalidOperationException>((context, ex) => context.Request.CreateErrorInfoResponse(System.Net.HttpStatusCode.BadRequest, "Invalid Operation", exception: ex));
GlobalConfiguration.Filters.Add(exceptionFormatter)
接下来，创建一个包罗万象的路由，将所有未知请求发送到新的错误处理程序:
Next, create a catchall route to send all unknown requests to your new Error handler:
config.Routes.MapHttpRoute(
name: "DefaultCatchall",
routeTemplate: "{*url}",
defaults: new {
controller = "Error",
action = "404"
}
);
并且，总而言之，通过将其添加到您的 web.config 中，让 IIS 通过 ASP.NET 处理所有请求:
And, to wrap it all up, let IIS process all requests through ASP.NET by adding this to your web.config:
<configuration>
<system.webServer>
<modules runAllManagedModulesForAllRequests="true" />
</system.webServer>
</configuration>
或者，您还可以使用 web.config 的 customErrors 部分将所有错误重定向到新的错误处理程序.
Optionally, you could also use the customErrors section of the web.config to redirect all errors to your new error handler.
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