Linq Query Left Loin

            var orderForBooks = (from bk in GetMasterUpload()

                                join ordr in GetDocumentSharing() on bk.Upload_ID equals ordr.Upload_ID

                                into a

                               from b in a.DefaultIfEmpty(new Master_User_DocumentSharing())

                                select new

                                {

                                    bk.Upload_ID,

                                    bk.Upload_ImageThumbNailLink,

                                    bk.Upload_FileType,

                                    bk.Upload_FileSize,

                                    bk.Upload_ReferenceName,

                                    b.Login_User_ID,

                                    b.SharingLoginUserId,

                                    bk.InsertedOn

                                }).ToList();

             var result = (from a in orderForBooks

                         // join b in GetDocumentSharing() on a.Upload_ID equals b.Upload_ID

                          join c in GetMaster_Login_User() on a.SharingLoginUserId equals c.Login_User_ID

                          join d in GetMaster_User_Registration() on c.User_RegistrationId equals d.User_RegistrationId

                          join n in GetMasterUploadLookup() on a.Upload_ID equals n.Upload_ID

                          select new

                          {

                              n.IsHiden,

                              c.Login_User_ID,

                              a.SharingLoginUserId,

                              n.UploadLookup_Id,

                              a.Upload_ID,

                              a.Upload_ImageThumbNailLink,

                              //m.Upload_FileLink,

                              a.Upload_FileSize,

                              a.Upload_ReferenceName,

                              Upload_FileType ="PDF", //getTypeimage(a.Upload_FileType),

                              SharingLoginUserName1 = getimagessss(c.Login_User_ID, a.Upload_ID, 0),

                              SharingLoginUserName2 = getimagessss(c.Login_User_ID, a.Upload_ID, 1),

                              SharingLoginUserName3 = getimagessss(c.Login_User_ID,a.Upload_ID, 2),

                              //SharingLoginUserName1 = GetImages(a.Upload_ID, 1),

                              //SharingLoginUserName2 = GetImages(a.Upload_ID, 2),

                              //SharingLoginUserName3 = GetImages(a.Upload_ID, 3),

                              //  SharingLoginUserName2 = d.User_ProfileImage_Thumbnail,

                              // SharingLoginUserName3 = d.User_ProfileImage_Thumbnail,

                              InsertedOn = Convert.ToDateTime(a.InsertedOn).ToString("dd/MM/yyyy"),

                          }).GroupBy(c => c.Upload_ID).Select(x => x.FirstOrDefault()).ToList();

            if (result.ToList().Count() > 0)

            {

                return Json(result.ToDataSourceResult(req), JsonRequestBehavior.AllowGet);

            }

            else

            {

                return null;

            }

        }