var valuesCf = (from cfv in com.CustomFieldValues
                                join trCf in com.TempRapports on cfv.CustomField_id equals trCf.Ressource_Id
                                join trP in com.TempRapportsProjects on cfv.Project_id equals trP.Project_Id
                                where trP.ID == guidRap && trCf.ID == guidCf
                                select cfv).ToList().GroupBy(x => x.Project_id).ToDictionary(o => o.Key, o => o.ToList());