我正在使用RestSharp构建一个HTTP API客户端,我注意到,当服务器返回HTTP错误代码(401未经授权,404未找到,内部服务器错误等)时,RestClient.Execute()不会抛出一个异常 – 而是使用一个空的.Data属性获取一个有效的RestResponse.我不想手动检查我的API客户端中的每个可能的HTTP错误代码 – RestSharp是否提供了一种将这些错误传递到我的客户端应用程序的更好方法？
一点点细节. RestSharp公开一个Response.ErrorException属性 – 如果RestClient.Execute< T&()调用引发任何异常,它将通过ErrorException属性公开,而不是抛出.他们的文档包括以下示例：
// TwilioApi.cs
public class TwilioApi {
const string BaseUrl = "https://api.twilio.com/2008-08-01";
public T Execute<T>(RestRequest request) where T : new()
{
var client = new RestClient();
client.BaseUrl = BaseUrl;
client.Authenticator = new HttpBasicAuthenticator(_accountSid,_secretKey);
request.AddParameter("AccountSid",_accountSid,ParameterType.UrlSegment); // used on every request
var response = client.Execute<T>(request);
if (response.ErrorException != null)
{
const string message = "Error retrieving response. Check inner details for more info.";
var twilioException = new ApplicationException(message,response.ErrorException);
throw twilioException;
}
return response.Data;
}
}
我在代码中采用了这种模式,但是我的API服务器返回了401 Unauthorized,但是ErrorException属性仍然为空.我可以在RestResponse.StatusCode和RestResponse.StatusDescription属性中看到未经授权的状态代码和错误消息 – 但是我为什么未经授权的响应不会导致ErrorException字段被填充,我感到困惑.
解决方法
尝试为RestSharp WebAPI客户端创建一个通用的错误处理程序时遇到同样的问题.给出这些扩展方法：
public static class RestSharpExtensionMethods
{
public static bool IsSuccessful(this IRestResponse response)
{
return response.StatusCode.IsSuccessStatusCode()
&& response.ResponseStatus == ResponseStatus.Completed;
}
public static bool IsSuccessStatusCode(this HttpStatusCode responseCode)
{
int numericResponse = (int)responseCode;
return numericResponse >= 200
&& numericResponse <= 399;
}
}
我提出要求反应是反序列化的：
public async Task<ResponseModel<TResponse>> PerformRequestAsync<TResponse>(IRestRequest request)
{
var response = await _client.ExecuteTaskAsync<ResponseModel<TResponse>>(request);
ResponseModel<TResponse> responseData;
if (response.IsSuccessful())
{
responseData = response.Data;
}
else
{
string resultMessage = HandleErrorResponse<TResponse>(request,response);
responseData = new ResponseModel<TResponse>
{
Success = false,ResultMessage = resultMessage
};
}
return responseData;
}
但是,在测试期间,我发现当我没有为这种情况配置错误处理时,当请求未映射的URL时,我的Web服务返回HTML格式的404页面.这导致response.ErrorException属性包含以下字符串：
Reference to undeclared entity ‘nbsp’. Line n,position m.
显然,RestSharp尝试将响应解析为XML,即使内容类型是text / html.也许我会给RestSharp提出一个问题.
当然在生产中,你不应该在打电话给自己的服务时得到404,但是我希望这个客户端是彻底的,可重用的.
所以我可以想到两个解决方案：
>检查状态代码并显示说明
>确保服务返回一个可以解析的错误对象
前者是很容易完成的.在HandleErrorResponse()中,我根据状态代码的数值构建结果消息(用户可呈现)和错误字符串(loggable)：
public string HandleErrorResponse(IRestRequest request,IRestResponse response)
{
string statusString = string.Format("{0} {1} - {2}",(int)response.StatusCode,response.StatusCode,response.StatusDescription);
string errorString = "Response status: " + statusString;
string resultMessage = "";
if (!response.StatusCode.IsScuccessStatusCode())
{
if (string.IsNullOrWhiteSpace(resultMessage))
{
resultMessage = "An error occurred while processing the request: "
+ response.StatusDescription;
}
}
if (response.ErrorException != null)
{
if (string.IsNullOrWhiteSpace(resultMessage))
{
resultMessage = "An exception occurred while processing the request: "
+ response.ErrorException.Message;
}
errorString += ",Exception: " + response.ErrorException;
}
// (other error handling here)
_logger.ErrorFormat("Error response: {0}",errorString);
return resultMessage;
}
现在,由于我的API响应总是包装在一个ResponseModel< T>我可以使用set up an exception filter and a NotFound route在ResultMessage属性中返回带有错误或异常消息的可解析响应模型：
public class HandleErrorAttribute : ExceptionFilterAttribute
{
public override void OnException(HttpActionExecutedContext context)
{
// (log context.Exception here)
context.Response = context.Request.CreateResponse(HttpStatusCode.InternalServerError,new ResponseModel<object>
{
Success = false,ResultMessage = "An exception occurred while processing the request: " + context.Exception.Message
});
}
}
和：
public class ErrorController : ApiController
{
public HttpResponseMessage Handle404()
{
const string notFoundString = "The requested resource could not be found";
var responseMessage = Request.CreateResponse(HttpStatusCode.NotFound,ResultMessage = notFoundString
});
responseMessage.ReasonPhrase = notFoundString;
return responseMessage;
}
}
这样,我的服务的响应总是可以由RestSharp解析,我可以使用通用日志记录方法：
public string HandleErrorResponse<TResponseModel>(IRestRequest request,IRestResponse<<ResponseModel<TResponseModel>> response)
并记录实际响应//(其他错误处理),如果可用：
if (response.Data != null && !string.IsNullOrWhiteSpace(response.Data.ResultMessage))
{
resultMessage = response.Data.ResultMessage;
errorString += string.Format(",Service response: \"{0}\"",response.Data.ResultMessage);
}
