如何在foreach循环中使用linq lambda C#MVC剃刀从关系数据库中枚举用户选择的专业名称

各位程序员，您好！

当谈到MVC C#时，我有点新手，但这是我的问题。我有三个关系MySQL表；用户、标题和用户标题。

用户如下所示：

+---------------+----------+
| currentUserId | UserName |
+---------------+----------+
|             1 | Dave     |
+---------------+----------+

标题如下：

+---------+-------+
| TitleId | Title |
+---------+-------+
|       1 | BS    |
|       2 | MD    |
|       3 | PHD   |
|       4 | BA    |
+---------+-------+

UserTitles如下所示：

+--------+---------+
| UserId | TitleId |
+--------+---------+
|      1 |       1 |
|      1 |       2 |
|      1 |       3 |
|      1 |       4 |
+--------+---------+

现在在我看来，我想根据数据库中分配给Dave的专业名称显示"Dave，BS，MD，PHD，BA"。

现在我可以在MySQL查询中轻松地做到这一点，并且它将起作用：

select Title from titles
INNER JOIN UserTitles on UserTitles.TitleId = titles.TitleId
where UserTitles.UserId = currentUserId;

现在我必须把这个变成林克兰布达。这就是我所做的，它没有任何错误。

控制器内：

ViewData.Add("FirstName", Users.Name);
var thisresult =
_contentService.Titles.Join(_contentService.UserTitles,
x => x.Id, y => y.TitleId, (x, y) => new {x, y})
.Where(@t => @t.y.UserId == currentUserId)
.Select(@t => new SelectListItem {Value = @t.x.TitleString}).ToList();

更新(感谢所有的支持(

IEnumerable<String> thisresult = _contentService.Titles
.Join(_contentService.UserTitles.Where(x => x.UserId == currentUserId),
t => t.Id,
ut => ut.TitleId,
(t, ut) => t.TitleString);
var model = new ManageUserViewModel()
{
 Titlelist = thisresult.ToList()
};
return View(model);

其中_contentService调用我的数据库。

In-ViewModel：

public IEnumerable<SelectListItem> Titlelist { get; set; }

更新

public IEnumerable<String> Titlelist { get; set; }

视图中：

 @ViewBag.FirstName,
 @foreach (var x in Model.Titlelist)
            {@x.Value}

更新

@foreach (var title in Model.Titlelist)
            {
                @Html.Raw(title)
            }

输出：

"/"应用程序中的服务器错误。不支持指定的方法。

有什么想法吗？

var thisresult =
_contentService.Titles.Join(_contentService.UserTitles, 
x => x.Id, y => y.TitleId, (x, y) => new {x, y})
.Where(@t => @t.y.UserId == currentUserId)
.Select(@t => new {Title = @t.x.TitleString}).ToList();

var thisresult =
_contentService.Titles.Join(_contentService.UserTitles, 
x => x.Id, y => y.TitleId, (x, y) => new {x, y})
.Where(@t => @t.y.UserId == currentUserId)
.Select(@t => new SelectListItem{
  Selected = //write your stuff here ,
  Text = //write your stuff here //,
  Value = //write your stuff here  }).ToList();

var thisresult =  _contentService.Titles.Join(_contentService.UserTitles, 
x => x.TitleId, y => y.TitleId, (x, y) => new {x, y})
.Where(@t => @t.y.UserId == currentUserId)
.Select(@t => new SelectListItem{
  Selected = //write your stuff here ,
  Text = //write your stuff here //,
  Value = //write your stuff here  }).ToList();

var thisresult = from t in _contentService.Titles
                join ut in _contentService.UserTitles on t.titleid equals ut.titleid
                where ut.userid == currentUserId
                select new SelectListItem
                {  Display = t.title, Value = t.titleId };