Entity Framework returning distinct records issue

Question

I have a PC Enity which have some Properties , I would like to return a list of distinct Object (PC or Complex Type or whatever ) based on a property in order to bind it to server controls like DropDownList . And Because my method located in BLL I can't return anonymous type , So I created a Branch ComplexType which has two peroperties.

I wrote like this but it have repeative records:

List<Branch> result = ( from p in _context.PCs
                        where p.UserId== userId
                        select new Branch()
                                   {
                                      BranchId= p.BranchId,
                                      BranchName=p.BranchName
                                   }).Distinct().ToList();

Edit : Thank you all , This worked :

List<PC> result = _context.PCs
                  .GroupBy(p=>p.BranchName , p.BranchId})
                  .select(g=>g.First())
                  .ToList();

Answer 1

this will return distinct rows for all the columns in the select statement. If you want distinct rows for a particular column just specify that particular column

List<Branch> result = ( from p in _context.PCs
                        where p.UserId== userId
                        select new Branch()
                                   {
                                      BranchId= p.BranchId,
                                    }).Distinct().ToList();

If you want to get distinct values based on multiple columns, then you have to create a group and then pick first value from that group. In that case you will not use Distinct, for example

List<Branch> distinctResult = _context.PCs
  .GroupBy(p => new Branch {p.BranchId, p.BranchName} )
  .Select(g => g.First())
  .ToList();