How to fix the query results cannot be enumerated more than once error in foreach loop

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I am sending jquery ajax call to get this data , so during this call , sometimes i recevive this error

XML

public static List<object> GetExcelDataforOjective(GoogleChartReportFilters objFilter, int? companyId, string ObjectiveStatus)
        {
            ActusSystemDataContext _db = new ActusSystemDataContext();
            int dataForYear = Company.GetCompaniesCurrentBusinessyear().company_StartDate.Year;
            System.Data.Linq.ISingleResult<usp_GetEmployeeListForObjectiveChartResult> objectiveResult = null;
            objectiveResult = _db.usp_GetEmployeeListForObjectiveChart(dataForYear,
                                                                    companyId, objFilter.DateFilter, objFilter.MoreThanLessThanStatus,
                                                                    objFilter.MoreThanLessThanValue, objFilter.ObjectivesStatus, objFilter.ObjectivePeriod);
            List<object> lstObj = new List<object>();

            foreach (var result in objectiveResult.ToList())
            {
                if (result.Objective_Status == ObjectiveStatus)
                {
                    ActusLibrary.Objectives obj = new ActusLibrary.Objectives();

                    obj.ObjectiveStatus = result.Objective_Status;
                    obj.EmpName = result.EmployeeName;
                    obj.Business_unit = result.Business_unit;
                    obj.Department = result.Department;
                    obj.Team = result.Team;
                    obj.Location = result.Location;
                    obj.ManagerName = result.ManagerName;
                    lstObj.Add(obj);
                }
            }
            return lstObj;
        }

Posted 28-May-15 19:43pm

Torakami

Updated 28-May-15 20:02pm

v2

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Sergey Alexandrovich Kryukov 29-May-15 2:04am

Error? What error?
—SA

Torakami 29-May-15 2:23am

query result can not be enumerated more than once during foreach loopinng

1 solution

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Sascha Lefèvre · Accepted Answer · 2015-05-28T20:29:00

Solution 1

I assume you have a concurrency problem there because objectiveResult apparently is a class member and not a local variable. So while one call to this method is about to execute ToList() on objectiveResult, another call overwrites it as it finishes the the query call to _db.usp_GetEmployeeListForObjectiveChart(..) and then both try to execute ToList() on the same query result object. Make objectiveResult a local variable of that method and it should be good.

edit: Illustration of variable declaration scope:

C#

class SomeClass
{
    int SomeMemberVariable; // declared as class member

    void SomeMethod()
    {
        int someLocalVariable; // declared locally in method

        SomeMemberVariable = 1; // class member (analog to objectiveResult)
    }
}

You declared objectiveResult as a class member like SomeMemberVariable in this example. You need to declare it locally like someLocalVariable instead.

Posted 28-May-15 20:29pm

Sascha Lefèvre

Updated 28-May-15 21:47pm

v2

Comments

_Asif_ 29-May-15 2:41am

+5

Torakami 29-May-15 3:21am

objectiveResult is my local variable only

Sascha Lefèvre 29-May-15 3:29am

I assume you misunderstand: You use it locally but you didn't declare it locally. The declaration is the line where the type name is specified in front of it.

Torakami 29-May-15 3:35am

I really didnt get this point , can you please show me what do u mean by that by showing an example for this for declaration ,

is this mean by declaring with new keyword and then assigning the value to it. ?

sorry for the inconvenience but may be you the one who is genius who can explain me very well .. thanks brother

Sascha Lefèvre 29-May-15 3:47am

Please see my answer above, after "edit".

Torakami 29-May-15 12:53pm

thanks man

Sascha Lefèvre 29-May-15 13:09pm

You're welcome!

Sascha Lefèvre 29-May-15 5:36am

Thank you, Asif.

Sergey Alexandrovich Kryukov 29-May-15 10:11am

5ed.
—SA

Sascha Lefèvre 29-May-15 10:17am

Thank you, Sergey.