EntityFramework- Error in converting to to 'System.Collections.Generic

Riddhi Valecha

Hello Team,

My Code is -

namespace Models
{
public class getChildQuestions
{
public int qid { get; set; }
public string qname { get; set; }
}
public class GetCPQuestionMasterModel
{

public Int32 QID_Get { get; set; }

public List Child_Question_Get { get; set; }

public Int32 Active_Get { get; set; }

}
}
-----------------------------
namespace DAL
{
public static List SubQuestions(Int32 QuestionID)
{

CPContext Context = new CPContext();

var SubQuestions = (from CB in Context .Question_Master
where CB.FKQID == QuestionID
select new getChildQuestions
{
qid = CB.QID,
qname = CB.Question
});

return SubQuestions.ToList();
}

---------
public List GetQuestionMaster(GetCPModel _Req)
{
CPContext Context = new CPContext ();

List _resReponseModel = null;
Int32 QuestionMasterCount = Context.Question_Master.Count();
if (QuestionMasterCount > 0)
{
_resReponseModel = (from p in Context.Question_Master

select new GetCPModel
{
QID_Get = p.QID,
Child_Question_Get = SubQuestions(p.FKQID),
Active_Get = p.Active,

}).ToList();

}
return _resReponseModel ;

}
}

-------------

On Line "Child_Question_Get = SubQuestions(p.FKQID), ", I am

I am getting an error -"Error in converting "how are you" to 'System.Collections.Generic.List`.

Please guide .. ITs really urgent.

12 Replies

Know the answer? Post it — somebody with the same question will find it here.

Riddhi Valecha5y ago
Hello sir...
I am not getting how to bind this method... I need to get the output in controller - it is httpget method.

[Route("GetAdminQuestionMaster")]
[HttpGet]
public IActionResult GetAdminQuestionMaster(CPQuestionMasterModel _reqCPQuestionMasterModel)
{
Response responseGet = new Response();
var lstRecords = new CPQuestionMaster().GetQuestionMaster();
}
Riddhi Valecha5y ago
Hello sir.. I am again stuck up.. I am sharing my code -

public class QuestionMasterModel
{

[Key]
public Int32 QID { get; set; }
[Required(ErrorMessage = "Please Provide Question")]
public string Question { get; set; }
}
---
public class GetQuestionMasterModel
{
public Int32 QID_Get { get; set; }
public string Parent_Question_Get { get; set; }
public List Children { get; set; }
}
--------------
public List GetTree(List list, int FKQID)
{
return list.Where(x => x.ParentQuestionID_Get == FKQID).Select(x => new CP_Question_Master
{
QID_Get = x.QID_Get,
Parent_Question_Get = x.Parent_Question_Get,
Children = GetTree(list, x.QID_Get)
}).ToList();
}
-------------------------------
public List GetQuestionMaster()
{
List _resReponseQuestionMasterModel = null;
Int32 QuestionMaster_Count = DBQuestionMasterContext.CP_Question_Master.Count();
if (QuestionMaster_Count > 0)
{
_resReponseQuestionMasterModel = (from p in DBQuestionMasterContext.Question_Master
where p.FKQID == 0
select new GetQuestionMasterModel
{
QID_Get = p.QID,

Children = GetTree(p.Children , p.FKQID),
}).ToList();
}
return _resReponseQuestionMasterModel;

}
Sachin Singh5y ago
this is another solution to traverse through last child (if any)
public static List GetChildren(List categories, int parentId)
       {
           return categories
                   .Where(c => c.FKQID == parentId)
                   .Select(c => new QuestionSet { QID = c.QID, Question = c.Question,  Children = GetChildren(categories, c.QID) })
                   .ToList();
       }

       public static void HieararchyWalk(List hierarchy)
       {
           if (hierarchy != null)
           {
               foreach (var item in hierarchy)
               {
                   Console.WriteLine(string.Format("{0} {1}", item.QID, item.Question));
                   HieararchyWalk(item.Children);
               }
           }
       }

public class QuestionSet
   {
       public int QID { get; set; }
       public int FKQID { get; set; }
       public string Question { get; set; }

       public List Children { get; set; }

   }

List questions = new List()
   {
       new QuestionSet(){QID=1,FKQID=0,Question="please rate"},
       new QuestionSet(){QID=2,FKQID=1,Question="problem with "},
       new QuestionSet(){QID=3,FKQID=2,Question="driver"},
       new QuestionSet(){QID=4,FKQID=3,Question="driver rude "},
       new QuestionSet(){QID=5,FKQID=3,Question="driving fast"},
       new QuestionSet(){QID=6,FKQID=2,Question="car"},
       new QuestionSet(){QID=7,FKQID=6,Question="car dirty"},
       new QuestionSet(){QID=8,FKQID=6,Question="car noisy"},



   };
Sachin Singh5y ago
hii
follow below approach its simple, just try to understand recursion and nothing required.
public List GetTree(List list, int FKQID)
      {
          return list.Where(x => x.FKQID == FKQID).Select(x => new QuestionSet
          {
              QID = x.QID,
              Question = x.Question,
              Children = GetTree(list, x.QID)
          }).ToList();
      }

     public class QuestionSet
  {
      public int QID { get; set; }
      public int FKQID { get; set; }
      public string Question { get; set; }

      public List Children { get; set; }

  }
Now enter any Id as parentId(FKQID) to know their children
Riddhi Valecha5y ago
Hello sir,
Could you please share the get;set properties of the class files ?
Riddhi Valecha5y ago
Hello sir,

I am sharing my code- perhaps you could help now..
public static List SubQuestions(Int32 QuestionID)
{
Int32 id = 0;
CPQuestionMasterContext DBQuestionMasterContext = new CPQuestionMasterContext();
var SubQuestions = (from CB in DBQuestionMasterContext.Question_Master
where CB.FKQID == QuestionID
select new getChildQuestions
{
qid = CB.QID,
qname = CB.Question,
qlist = SubQuestions1(CB.QID),
qlist1 = SubQuestions2(Convert.ToInt32(SubQuestions1(CB.QID).ElementAt(0).qid))
});
return SubQuestions.ToList() ;
}
public static List SubQuestions1(Int32 QuestionID)
{
CPQuestionMasterContext DBQuestionMasterContext = new CPQuestionMasterContext();
var SubQuestions = (from CB in DBQuestionMasterContext.Question_Master
where CB.FKQID == QuestionID
select new getChildQuestions
{
qid = CB.QID,
qname = CB.Question,
});
return SubQuestions.ToList();
}
public static List SubQuestions2(Int32 QuestionID)
{
CPQuestionMasterContext DBQuestionMasterContext = new CPQuestionMasterContext();
var SubQuestions = (from CB in DBQuestionMasterContext.Question_Master
where CB.QID == QuestionID
select new getChildQuestions
{
qid = CB.QID,
qname = CB.Question,
});
return SubQuestions.ToList();
}
Sachin Singh5y ago
hii
Riddhi
why don't you use recursion to achieve heirarichal data
public List GetTree(List list, int FKQID)
       {
           return list.Where(x => x.FKQID == FKQID).Select(x => new GetAllQuestions
           {
               QID_Get = x.QID,
               ParentQuestion_get = x.Question,
               subQuestions = GetTree(list, x.QID)  // it is also list of MasterQuestion //table
           }).ToList();
       }
Riddhi Valecha5y ago
Hello Sachin sir,

My requirement is - I need to get all the records using EntityFrame Work and Linq.

So, my method is -
public List GetAllQuestions(GetAllQuestions objgetquestions)
{
var questions = (from a in questioncontext.Question_Master select new
QID_get = a.QID ,
ParentQuestion_get = a.Question
}
--------
How do I get the list here in ParentQuestion and SubQuestion
--
Here "GetAllQuestions" is the name of the class , and "QID_Get" and "ParentQuestion_get" are get ; set; properties.
public class GetAllQuestions { public int QID_Get {get;set;} public string ParentQuestion_get{get;set;} , public List {get;set;} },
public class SubQuestions { public int QID_Get {get;set;} public string SubQuestion_get{get;set;}}
-------------
I need to make class structure something like this.... How do I complete this ?

Hello Team.. PLease help me in this... Its really urgent.
Sachin Singh5y ago
this is very basic , what is your exact issue?
this is how can you get all question with subquestion thier option and counter question
public static void Main()
     {


         List questions = new List()
{
     new QuestionSet(){QID=1,FKQID=0,Question="please rate"},
     new QuestionSet(){QID=2,FKQID=1,Question="problem with "},
     new QuestionSet(){QID=3,FKQID=2,Question="driver"},
     new QuestionSet(){QID=4,FKQID=3,Question="driver rude "},
     new QuestionSet(){QID=5,FKQID=3,Question="driving fast"},
     new QuestionSet(){QID=6,FKQID=2,Question="car"},
     new QuestionSet(){QID=7,FKQID=6,Question="car dirty"},
     new QuestionSet(){QID=8,FKQID=6,Question="car noisy"},



};

         var parent_Question = questions.Where(x => x.FKQID == 0).Single();
         Console.WriteLine("parent question is---->"+parent_Question.Question);
         var sub_Question = questions.Where(x => x.FKQID == parent_Question.QID).Single();
         Console.WriteLine("Sub question is---->"+sub_Question.Question);
         var sub_Question_Questions = questions.Where(x => x.FKQID == sub_Question.QID).ToList();
         int i = 1;
         foreach (var subquestion in sub_Question_Questions)
         {

             Console.WriteLine("option"+i+ "is:--->"+subquestion.Question);
             foreach (var childofsub in questions.Where(x=>x.FKQID==subquestion.QID))
             {
                 Console.WriteLine("question is---->"+childofsub.Question);
             }
             i++;
         }


         Console.ReadLine();
     }

Riddhi Valecha5y ago

Hello Sir,

I will show the Database structure and the output that I need -

Database structure -

QID	Question	FKQID
1	please rate	0
2	problem with	1
3	driver	2
4	driver rude	3
5	driving fast	3
6	car	2
7	car dirty	6
8	car noisy	6

The output that I need here is -

parent_question : "Please rate",
sub_question : "problem with"
{
Sub_ques_ques : driver
{
Sub_ques_ques_opt : driver rude,
Sub_ques_ques_opt : driving fast
},
Sub_ques_ques : car
{
Sub_ques_ques_opt : car dirty,
Sub_ques_ques_opt : car noisy
}
}
}
--
FKQID == 0 => parent_question
FKQID != 0 => sub_question
"problem with" is the sub_question of "Please rate"
"driver" and "car" are options for question "problem with"
"driver rude", "driving fast" are options for question "driver"
"car dirty" and "car noisy" are options for question "car"
-----

Please help in this.

Riddhi Valecha5y ago
Hello sir,
I have shared the method of keeping the data.

Please help me out with the output.... I tried doing it multiple times, but it is not working.
Sachin Singh5y ago
remove the static keyowrd and also change the variable name other than the method name
var SubQuestions = (from CB in Context .Question_Master , change SubQuestions to something else like Sq etc.