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c#sql-serverentity-frameworklinq-to-entities
Robertcode
Robertcode

Reputation: 1009

Do Multiple Linq To Entity Queries In Entity Framework Using One DBContext Connect Only Once To The Database

I am trying to return two result sets from an SQL Server database using Entity Framework 6. I would like to try this by running 2 Linq to Entity queries using a single DBContext. My question is by using a single DBContext is whether my request is only being hit by a database connection once. I think it is but I am not sure.

class RequestRefLists
{
  public List<Employee> EmployeeList {get;set;}
  public List<Dept> DeptList {get;set;}
}

    public RequestRefLists GetRequestRefLists()
   {
    RequestRefLists ReqRefLists = new RequestRefLists();

    using(var context= new BusinessDBContext())
    { 
      var queryResult1 = from e in context.Employees
      select e;
      ReqRefLists.EmployeeList = (List<Employee>)queryResult1.ToList();

      var queryResult2 = from d in context.Departments
      select d;
      ReqRefLists.DeptList = (List<Dept>)queryResult2.ToList();
    }
    return ReqRefLists;
   }

Upvotes: 7

Views: 7939

Answers (1)

Vadim Martynov
Vadim Martynov

Reputation: 8902

You can use Entity Framework Extended Library.

There is a feature named Future queries

class RequestRefLists
{
    public List<Employee> EmployeeList {get;set;}
    public List<Dept> DeptList {get;set;}
}

public RequestRefLists GetRequestRefLists()
{
    RequestRefLists ReqRefLists = new RequestRefLists();

    using(var context= new BusinessDBContext)
    { 
        var queryResult1 = from e in context.Employees
        select e;
        ReqRefLists.EmployeeList = queryResult1.Future();

        var queryResult2 = from d in context.Departments
        select d;
        ReqRefLists.DeptList = queryResult2.Future();        
    }
    return ReqRefLists;
}

Your queries will execute lazy on first enumeration of any collection.

ExecuteFutureQueries builds a batch query from all the stored IFutureQuery objects. Finally, all the IFutureQuery objects are updated with the results from the query.

Upvotes: 8

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