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c# - Web api 操作中的 IHttpActionResult 错误

问题描述

我在 web 服务器中面临方法未找到错误，但在 Visual Studio 本地它可以工作：

    [HttpGet]
    [Route("api/checkhealth")]
    public async Task<IHttpActionResult> CheckHealth()
    {
        var message = "checkhealth method was invoked";
        return new TextResult(message, Request);
    }

然后在浏览器中出现以下错误：

    <Error>
    <Message>An error has occurred.</Message>
    <ExceptionMessage>Method not found: 'System.Net.Http.HttpRequestMessage System.Web.Http.ApiController.get_Request()'.
    </ExceptionMessage>
    <ExceptionType>System.MissingMethodException</ExceptionType>
    <StackTrace>at BMI.Controllers.APIController.<CheckHealth>d__0.MoveNext() at System.Runtime.CompilerServices.AsyncTaskMethodBuilder`1.Start[TStateMachine](TStateMachine& stateMachine) at BMI.Controllers.APIController.CheckHealth() at lambda_method(Closure , Object , Object[] ) at System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ActionExecutor.<>c__DisplayClass6_3.<GetExecutor>b__2(Object instance, Object[] methodParameters) at 
      System.Web.Http.Controllers.ReflectedHttpActionDescriptor.ExecuteAsync(HttpControllerContext controllerContext, IDictionary`2 arguments, CancellationToken cancellationToken) --- End of stack trace from previous location where exception was thrown --- at 
      System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Controllers.ApiControllerActionInvoker. 
       <InvokeActionAsyncCore>d__1.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Controllers.ActionFilterResult. 
       <ExecuteAsync>d__5.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Dispatcher.HttpControllerDispatcher. 
      <SendAsync>d__15.MoveNext()
      </StackTrace>
     </Error>

我已经实现了 IHttpActionResult 如下：

    public class TextResult : IHttpActionResult
    {
        string message;
        HttpRequestMessage request;

        public TextResult(string message, HttpRequestMessage request)
        {
            this.message = message;
            this.request = request;
        }
        public Task<HttpResponseMessage> ExecuteAsync(CancellationToken cancellationToken)
        {
            var response = new HttpResponseMessage()
            {
                Content = new StringContent(message),
                RequestMessage = request
            };
            return Task.FromResult(response);
        }
    }

我项目中的实际方法是 post，但在这里我尝试先用 get 修复，然后我相信 post 也可以。

这里要提到以下方法完美地工作，所以我认为 IHttpActionResult 缺少一些东西：

    [HttpGet]
    [Route("api/getok")]
    public JsonResult<string> getJson()
    { 
        return Json("OK");
    }

你有没有人面临并解决了这个问题。请帮助我，在此先感谢。

标签： c#asp.net-web-apiasp.net-web-api2

解决方案

在请求上使用CreateResponse扩展名将允许将请求中的任何配置复制到响应中，当您像示例中那样手动创建响应时，可能会丢失这些配置。

public class TextResult : IHttpActionResult {
    string message;
    HttpRequestMessage request;

    public TextResult(string message, HttpRequestMessage request) {
        this.message = message;
        this.request = request;
    }
    public Task<HttpResponseMessage> ExecuteAsync(CancellationToken cancellationToken) {
        var response = request.CreateResponse(HttpStatusCode.OK, message);
        return Task.FromResult(response);
    }
}

此外，控制器操作未正确定义，因为它被定义为async Task<IHttpActionResult>当操作未执行任何异步操作时。

如果实际上不是异步的，则重构以遵循正确的语法。

[HttpGet]
[Route("api/checkhealth")]
public IHttpActionResult CheckHealth() {
    var message = "checkhealth method was invoked";
    return new TextResult(message, Request);
}

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