返回null值，其中需要httpresponsemessage的实例。 [英] A null value was returned where an instance of httpresponsemessage was expected.

问题描述

我正在执行以下代码以从Web API获取数据：

I am executing the following code to get data from Web API:

$(window).load(function () {
           var jsonObject = {
               "CompanyID": 1,
               "UserName": '30',
               "UserPwd": '30',
               "UserRole": 3,
               "RemoteHostIP": '8.8.8.8'
           };
           //debugger;
           $.ajax({
               type: "POST"
                , url: "http://localhost/ESSWebAPI/api/mobi/Login_User",
               data: JSON.stringify(jsonObject),
               contentType: "application/json;charset=utf-8",
               dataType: "json"
                        , success: function (data) {
                            console.log(data);
                        },
               error: function (response) {
                   alert(response.status + " " + response.statusText);
               }
           });
       });

我收到以下错误：



返回一个空值，其中预期有一个HttpResponseMessage实例。



System.InvalidOperationException



at System System.Web.Http.Controllers.ApiControllerActionInvoker中的.Web.Http.Controllers.ResponseMessageResultConverter.Convert（HttpControllerContext controllerContext，Object actionResult）。< invokeactionasynccore> d__0.MoveNext（）---来自先前位置的堆栈跟踪结束，其中异常是抛出---位于System.Web.Http.Controllers.ActionFilterResult的System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）的System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）。< executeasync> d__2.MoveNext （）---在抛出异常的前一个位置的堆栈跟踪结束---在Syst的System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务） System.Web.Http.Dispatcher.HttpControllerDispatcher上的em.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）。< sendasync> d__1.MoveNext（）



at System.Web.Http.Conttlers.ApiControllerActionInvoker中的System.Web.Http.Controllers.ResponseMessageResultConverter.Convert（HttpControllerContext controllerContext，Object actionResult）。< invokeactionasynccore> d__0.MoveNext（）---来自先前位置的堆栈跟踪结束在System.Web.Http.Controllers.ActionFilterResult的System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）的System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）中抛出了它。< executeasync> d__2。 MoveNext（）---从抛出异常的先前位置开始的堆栈跟踪结束---在System.Runtime.CompilerServices.TaskAwaiter.HandleNon上的System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）处System.Web.Http.Dispatcher.HttpControllerDispatcher上的SuccessAndDebuggerNotification（任务任务）。< sendasync> d__1.MoveNext（）





代码在我的Web API中

I am getting the following error:

A null value was returned where an instance of HttpResponseMessage was expected.

System.InvalidOperationException

at System.Web.Http.Controllers.ResponseMessageResultConverter.Convert(HttpControllerContext controllerContext, Object actionResult) at System.Web.Http.Controllers.ApiControllerActionInvoker.<invokeactionasynccore>d__0.MoveNext()--- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Controllers.ActionFilterResult.<executeasync>d__2.MoveNext()--- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Dispatcher.HttpControllerDispatcher.<sendasync>d__1.MoveNext()

at System.Web.Http.Controllers.ResponseMessageResultConverter.Convert(HttpControllerContext controllerContext, Object actionResult) at System.Web.Http.Controllers.ApiControllerActionInvoker.<invokeactionasynccore>d__0.MoveNext()--- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Controllers.ActionFilterResult.<executeasync>d__2.MoveNext()--- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Dispatcher.HttpControllerDispatcher.<sendasync>d__1.MoveNext()


Code in my Web API

[HttpPost]
       //[Route("api/Mobi/Login_User")]
       public HttpResponseMessage Login_User(Login obj)
       {
           try
           {
               tlbset.ESS.Login oLogin = new tlbset.ESS.Login();
               oLogin.UserName = obj.UserName;
               oLogin.UserPwd = obj.UserPwd;
               oLogin.CompanyID = obj.CompanyID;
               oLogin.UserRole = Convert.ToInt16(obj.UserRole);
               oLogin.RemoteHostIP = obj.RemoteHostIP;
               //RemoteHostName
               try
               {
                   System.Net.IPHostEntry host = default(System.Net.IPHostEntry);
                   host = System.Net.Dns.GetHostEntry(oLogin.RemoteHostIP);
                   oLogin.RemoteHostName = host.HostName;
               }
               catch
               {
               }

               List<Result> lstLogin = new List<Result>();

               DataSet dsResult = new DataSet("dsResult");
               DataTable dtLogin = new DataTable("dtLogin");
               DataTable dtMenu = new DataTable("dtMenu");

               dsResult.Tables.Add(dtLogin);
               dsResult.Tables.Add(dtMenu);

               if (oLogin.LoginUser())
               {
                   if (oLogin.EmpCngPwd == 0)
                   {
                       //VALID EMPLOYEE
                       dtLogin.Rows.Add(1, CT.Cryptography.Crypto.Encryption(oLogin.SessionID.ToString()));
                   }
                   else if (oLogin.EmpCngPwd == 1)
                   {
                       //PASSWORD EXPIRE
                       dtLogin.Rows.Add(3, "Your Password is expired");
                   }
                   else if (oLogin.EmpCngPwd == 2)
                   {
                       //CHANGE PASSWORD ON LOG ON
                       dtLogin.Rows.Add(3, "You must set password");
                   }
               }
               else
               {
                   //INVALID EMPLOYEE
                   dtLogin.Rows.Add(2, oLogin.ErrorMsg);
               }

               //MENU
               dtMenu = Get_Menu_Table();
               DataView dv;
               if (!oLogin.objEmployee.ReportingHead)
               {
                   //Pending Approvals
                   dv = dtMenu.DefaultView;
                   dv.RowFilter = "SNo<7 AND SNo>7.3";
                   dtMenu = dv.ToTable();

                   //Team Leave calendar
                   dv = dtMenu.DefaultView;
                   dv.RowFilter = "SNo<>9";
                   dtMenu = dv.ToTable();
               }

               //Employee Directory
               if (!oLogin.objSettings.ShowEmpDir)
               {
                   dv = dtMenu.DefaultView;
                   dv.RowFilter = "SNo<>10";
                   dtMenu = dv.ToTable();
               }

               //Web Punch
               if(!(oLogin.objSettings.ApplyMobilePunch && oLogin.objSettings.InclInMobilePunch))
               {
                   dv = dtMenu.DefaultView;
                   dv.RowFilter = "SNo<>11";
                   dtMenu = dv.ToTable();
               }

               //Payroll
               string sEmpPRModules = "";
               tlbset.ESS.Settings oSettings = new tlbset.ESS.Settings();
               if (oSettings.GetRecord())
                   sEmpPRModules = oSettings.EmpPRModules;
               if (sEmpPRModules != "")
               {//Salary Details
                   if (sEmpPRModules.Contains("1^1|") == false)
                   {
                       dv = dtMenu.DefaultView;
                       dv.RowFilter = "SNo<>8.1";
                       dtMenu = dv.ToTable();
                   }

                   //Salary register
                   if (sEmpPRModules.Contains("3^1|") == false)
                   {
                       dv = dtMenu.DefaultView;
                       dv.RowFilter = "SNo<>8.2";
                       dtMenu = dv.ToTable();
                   }

                   //if none of them is applicable
                   if (!sEmpPRModules.Contains("1^1|") && !sEmpPRModules.Contains("3^1|"))
                   {
                       dv = dtMenu.DefaultView;
                       dv.RowFilter = "SNo<8 AND SNo>8.2";
                       dtMenu = dv.ToTable();
                   }
               }
               return Request.CreateResponse(HttpStatusCode.OK, dsResult);
           }
           catch (Exception ex)
           {
               CTException.WriteDBLog(strCodeFile, "Login_User", ex.Message, ex.InnerException);
               return null;
           }
       }

我尝试了什么：



我试过将post方法更改为GEt。但它不起作用

What I have tried:

I have tried changing post method to GEt. But it doesnt work

推荐答案

（窗口）.load（function（）{
var jsonObject = {
CompanyID：1，
UserName：'30'，
UserPwd：'30'，
UserRole：3，
RemoteHostIP：'8.8.8.8'
};
//调试器;

(window).load(function () { var jsonObject = { "CompanyID": 1, "UserName": '30', "UserPwd": '30', "UserRole": 3, "RemoteHostIP": '8.8.8.8' }; //debugger;

.ajax（{
类型：POST
，url：http：// localhost / ESSWebAPI / api / mobi / Login_User，
data：JSON.stringify（jsonObject），
contentType：application / json; charset = utf-8，
dataType：json
，成功：函数（数据）{
console.log（数据）;
}，
错误：函数（响应）{
alert（response.status ++ response.statusText）;
}
}）;
}）;

.ajax({ type: "POST" , url: "http://localhost/ESSWebAPI/api/mobi/Login_User", data: JSON.stringify(jsonObject), contentType: "application/json;charset=utf-8", dataType: "json" , success: function (data) { console.log(data); }, error: function (response) { alert(response.status + " " + response.statusText); } }); });

我收到以下错误：



返回一个空值，其中预期有一个HttpResponseMessage实例。



System.InvalidOperationException



at System System.Web.Http.Controllers.ApiControllerActionInvoker中的.Web.Http.Controllers.ResponseMessageResultConverter.Convert（HttpControllerContext controllerContext，Object actionResult）。< invokeactionasynccore> d__0.MoveNext（）---来自先前位置的堆栈跟踪结束，其中异常是抛出---位于System.Web.Http.Controllers.ActionFilterResult的System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）的System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）。< executeasync> d__2.MoveNext （）---在抛出异常的前一个位置的堆栈跟踪结束---在Syst的System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务） System.Web.Http.Dispatcher.HttpControllerDispatcher上的em.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）。< sendasync> d__1.MoveNext（）



at System.Web.Http.Conttlers.ApiControllerActionInvoker中的System.Web.Http.Controllers.ResponseMessageResultConverter.Convert（HttpControllerContext controllerContext，Object actionResult）。< invokeactionasynccore> d__0.MoveNext（）---来自先前位置的堆栈跟踪结束在System.Web.Http.Controllers.ActionFilterResult的System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务任务）的System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）中抛出了它。< executeasync> d__2。 MoveNext（）---从抛出异常的先前位置开始的堆栈跟踪结束---在System.Runtime.CompilerServices.TaskAwaiter.HandleNon上的System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务任务）处System.Web.Http.Dispatcher.HttpControllerDispatcher上的SuccessAndDebuggerNotification（任务任务）。< sendasync> d__1.MoveNext（）





代码在我的Web API中

I am getting the following error:

A null value was returned where an instance of HttpResponseMessage was expected.

System.InvalidOperationException

at System.Web.Http.Controllers.ResponseMessageResultConverter.Convert(HttpControllerContext controllerContext, Object actionResult) at System.Web.Http.Controllers.ApiControllerActionInvoker.<invokeactionasynccore>d__0.MoveNext()--- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Controllers.ActionFilterResult.<executeasync>d__2.MoveNext()--- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Dispatcher.HttpControllerDispatcher.<sendasync>d__1.MoveNext()

at System.Web.Http.Controllers.ResponseMessageResultConverter.Convert(HttpControllerContext controllerContext, Object actionResult) at System.Web.Http.Controllers.ApiControllerActionInvoker.<invokeactionasynccore>d__0.MoveNext()--- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Controllers.ActionFilterResult.<executeasync>d__2.MoveNext()--- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Dispatcher.HttpControllerDispatcher.<sendasync>d__1.MoveNext()


Code in my Web API

[HttpPost]
       //[Route("api/Mobi/Login_User")]
       public HttpResponseMessage Login_User(Login obj)
       {
           try
           {
               tlbset.ESS.Login oLogin = new tlbset.ESS.Login();
               oLogin.UserName = obj.UserName;
               oLogin.UserPwd = obj.UserPwd;
               oLogin.CompanyID = obj.CompanyID;
               oLogin.UserRole = Convert.ToInt16(obj.UserRole);
               oLogin.RemoteHostIP = obj.RemoteHostIP;
               //RemoteHostName
               try
               {
                   System.Net.IPHostEntry host = default(System.Net.IPHostEntry);
                   host = System.Net.Dns.GetHostEntry(oLogin.RemoteHostIP);
                   oLogin.RemoteHostName = host.HostName;
               }
               catch
               {
               }

               List<Result> lstLogin = new List<Result>();

               DataSet dsResult = new DataSet("dsResult");
               DataTable dtLogin = new DataTable("dtLogin");
               DataTable dtMenu = new DataTable("dtMenu");

               dsResult.Tables.Add(dtLogin);
               dsResult.Tables.Add(dtMenu);

               if (oLogin.LoginUser())
               {
                   if (oLogin.EmpCngPwd == 0)
                   {
                       //VALID EMPLOYEE
                       dtLogin.Rows.Add(1, CT.Cryptography.Crypto.Encryption(oLogin.SessionID.ToString()));
                   }
                   else if (oLogin.EmpCngPwd == 1)
                   {
                       //PASSWORD EXPIRE
                       dtLogin.Rows.Add(3, "Your Password is expired");
                   }
                   else if (oLogin.EmpCngPwd == 2)
                   {
                       //CHANGE PASSWORD ON LOG ON
                       dtLogin.Rows.Add(3, "You must set password");
                   }
               }
               else
               {
                   //INVALID EMPLOYEE
                   dtLogin.Rows.Add(2, oLogin.ErrorMsg);
               }

               //MENU
               dtMenu = Get_Menu_Table();
               DataView dv;
               if (!oLogin.objEmployee.ReportingHead)
               {
                   //Pending Approvals
                   dv = dtMenu.DefaultView;
                   dv.RowFilter = "SNo<7 AND SNo>7.3";
                   dtMenu = dv.ToTable();

                   //Team Leave calendar
                   dv = dtMenu.DefaultView;
                   dv.RowFilter = "SNo<>9";
                   dtMenu = dv.ToTable();
               }

               //Employee Directory
               if (!oLogin.objSettings.ShowEmpDir)
               {
                   dv = dtMenu.DefaultView;
                   dv.RowFilter = "SNo<>10";
                   dtMenu = dv.ToTable();
               }

               //Web Punch
               if(!(oLogin.objSettings.ApplyMobilePunch && oLogin.objSettings.InclInMobilePunch))
               {
                   dv = dtMenu.DefaultView;
                   dv.RowFilter = "SNo<>11";
                   dtMenu = dv.ToTable();
               }

               //Payroll
               string sEmpPRModules = "";
               tlbset.ESS.Settings oSettings = new tlbset.ESS.Settings();
               if (oSettings.GetRecord())
                   sEmpPRModules = oSettings.EmpPRModules;
               if (sEmpPRModules != "")
               {//Salary Details
                   if (sEmpPRModules.Contains("1^1|") == false)
                   {
                       dv = dtMenu.DefaultView;
                       dv.RowFilter = "SNo<>8.1";
                       dtMenu = dv.ToTable();
                   }

                   //Salary register
                   if (sEmpPRModules.Contains("3^1|") == false)
                   {
                       dv = dtMenu.DefaultView;
                       dv.RowFilter = "SNo<>8.2";
                       dtMenu = dv.ToTable();
                   }

                   //if none of them is applicable
                   if (!sEmpPRModules.Contains("1^1|") && !sEmpPRModules.Contains("3^1|"))
                   {
                       dv = dtMenu.DefaultView;
                       dv.RowFilter = "SNo<8 AND SNo>8.2";
                       dtMenu = dv.ToTable();
                   }
               }
               return Request.CreateResponse(HttpStatusCode.OK, dsResult);
           }
           catch (Exception ex)
           {
               CTException.WriteDBLog(strCodeFile, "Login_User", ex.Message, ex.InnerException);
               return null;
           }
       }

我尝试了什么：



我试过将post方法更改为GEt。但它不起作用

What I have tried:

I have tried changing post method to GEt. But it doesnt work

您的API代码抛出异常。当发生这种情况时，您的操作将返回 null 而不是相应的响应消息。



更改 catch 阻止返回合适的响应消息：

Your API code is throwing an exception. When that happens, your action returns null rather than an appropriate response message.

Change your catch block to return a suitable response message:

catch (Exception ex)
{
    CTException.WriteDBLog(strCodeFile, "Login_User", ex.Message, ex.InnerException);
    return Request.CreateErrorResponse(HttpStatusCode.InternalServerError, ex);
}

然后，您需要检查日志文件以找出异常，并修复您的代码。

You will then need to check your log file to find out what the exception is, and fix your code.

这篇关于返回null值，其中需要httpresponsemessage的实例。的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！