Question

I’ve an Document object and User object, generated by Entity Framework Model Generator.

I want to get Document list, plus userCount created according to this Document.

So, I’ve created new object DocumentWithUserCount:

public class DocumentWithUserCount:Document
{
    public uAmount {get;set}
}

And LINQ to retain data (below code, I need your help) :

    var ed = (from d in _entity.Document
     join p in _entity.User[get DocID and count by this docID ] on d.RID equals p.DocID         
select new DocumentWithUserCount(xxxx)).ToList();

How to do this?

EDIT:
Simply I want to do equivalent code below with LINQ.

    SELECT d.*, p.* from Document d INNER JOIN (select docid, count(RID) as uAmount from User
    GROUP BY DocID) p ON d.RID=p.docid

Answer 1

I think that inheritance is the wrong tool here. Use composition instead. And It’s not clear if you even nneed the Join, there should be a navigation property:

var eds = from d in _entity.Document       
   select new { Document=d, UserCount=d.Users.Count() };  // anon type

or

public class DocumentWithUserCount  //:Document
{
    public Doucument { get; set; }
    public int Amount {get;set}
}
var eds = from d in _entity.Document       
   select new DocumentWithUserCount { Document=d, Amount=d.Users.Count() };