如何将项目添加到LINQ重新启动的列表中

Question

我有以下清单

 var listOfParks = (from s in DB.MasterDatas

                           select new SelectListItem
                           {
                               Text = s.service_under,

                           }).Distinct().Union(
                           from t in DB.MasterDatas
                            join f in DB.Users1
                           on t.pv_person_resp_id equals f.user_id     
                           select new SelectListItem
                           {
                               Text = f.user_name

                           }).ToList()

但我需要手动将"全部"添加到此列表中,我正在尝试这样做:

    var listOfParks = (from s in DB.MasterDatas

                           select new SelectListItem
                           {
                               Text = s.service_under,

                           }).Distinct().Union(
                           from t in DB.MasterDatas
                            join f in DB.Users1
                           on t.pv_person_resp_id equals f.user_id     
                           select new SelectListItem
                           {
                               Text = f.user_name

                           }).ToList().Add(new SelectListItem{Text="All"});

但我得到错误:无法将void分配给隐式类型的局部变量

Answer 1

你需要.Add在下一行,你不能用LINQ添加一行:

var listOfParks = (from s in DB.MasterDatas

                           select new SelectListItem
                           {
                               Text = s.service_under,

                           }).Distinct().Union(
                           from t in DB.MasterDatas
                            join f in DB.Users1
                           on t.pv_person_resp_id equals f.user_id     
                           select new SelectListItem
                           {
                               Text = f.user_name

                           }).ToList();
listOfParks.Add(new SelectListItem{Text="All"});

问题在于它试图分配给它不能.Add返回的回报.或者您可以使用,但实际上没有理由为了清晰起见您不能在单独的线路上使用它.voidlistOfParks.Concat