Entity Framework Core 使用选择和分组依据

Question

I want to use select and groupby in my query

_context.UserChart_Tbl
        .Where(uc => uc.UserID == "6")
        .GroupBy(g => g.OrgnizationID)
        .Select(g => g.OrgnizationID)
        .ToArray();

But I get an error in select

Error CS1061 'IGrouping' does not contain a definition for 'OrgnizationID' and no accessible extension method 'OrgnizationID' accepting a first argument of type 'IGrouping' could be found (are you missing a using directive or an assembly reference?)

How can I solve this problem?

Update

Error Solved by this code

_context.UserChart_Tbl
          .Where(uc => uc.UserID == u.Id)
          .GroupBy(g => g.OrgnizationID)
          .Select(g => g.Key).ToArray()

Complete Code

    public List<DoctorDropDoenViewModel> DoctorDropDown()
    {
        var query = (from u in _context.Users
                     join
                     UR in _context.UserRoles on u.Id equals UR.UserId
                     join
                     D in _context.Doctor_Tbl on u.Id equals D.DoctorUserId
                     where UR.PolicyID == 4

                     select new DoctorDropDoenViewModel()
                     {
                         DoctorID = u.Id,
                         DoctorFullName = u.FirstName + " " + u.Family,
                         OrgID = _context.UserChart_Tbl.Where(uc => uc.UserID == u.Id)
                         .GroupBy(g => g.OrgnizationID).Select(g => g.Key).ToArray()
                     });


      return query.ToList();
    }

And

public class DoctorDropDoenViewModel
{
    public string DoctorID { get; set; }
    public string DoctorFullName { get; set; }
    public int[] OrgID { get; set; }
}

DoctorID can have several OrgID Which may also be duplicates. I want to display duplicates only once. For this purpose i use Distinct and Group By .

But Group By not working

Answer 1

Wwhen you are grouping items property which you are using for group is going to 'Key' of the group. Replace Select(g => g.OrgnizationID) with Select(g => g.Key) it should help.

Answer 2

To get distinct elements from OrganizationID array, you need not to perform GroupBy, you have to create new dynamic object using .Select() method.

Try below solution, this might help you

public List<DoctorDropDoenViewModel> DoctorDropDown()
{
    var query = (from u in _context.Users
                 join
                 UR in _context.UserRoles on u.Id equals UR.UserId
                 join
                 D in _context.Doctor_Tbl on u.Id equals D.DoctorUserId
                 where UR.PolicyID == 4

                 select new DoctorDropDoenViewModel()
                 {
                     DoctorID = u.Id,
                     DoctorFullName = u.FirstName + " " + u.Family,
                     OrgID = _context.UserChart_Tbl
                     .Where(uc => uc.UserID == u.Id)
                     .Select(g => g.OrgnizationID)  //Select only OrganizationID from complete object
                     .Distinct()   //Remove duplicates.
                     .ToArray()    //Convert IEnumerable<T> to Array
                 });


  return query.ToList();
}

Answer 3

You can use the following code

_context.UserChart_Tbl.Where(uc => uc.UserID == u.Id)
.Where(x=>x.DoctorID==1).Select(g => g.OrgnizationID).Distinct().ToArray()}