Question

在我的网站上，我试图返回一个列表，其中显示当前用户正在关注的用户，但我一直在收到错误Cannot implicitly convert type 'System.Collections.Generic.List' to 'string'

任何帮助都会很棒

用户控制器

public ActionResult Index()
        {
            var manager = new UserManager<ApplicationUser>(new UserStore<ApplicationUser>(new ApplicationDbContext()));
            var currentUser = manager.FindById(User.Identity.GetUserId());
            return View(new Followuser()
                       {
                           User1ID = db.Followusers.Where(u => u.User1ID == currentUser.Id).ToList()
                       });

        }

关注用户模型

public class Followuser
    {
        [Key, Column(Order = 0)]
        public string User1ID { get; set; }

        [Key, Column(Order = 1)]
        public string User2ID { get; set; }


    }

Answer 1

你没有明显的原因打电话给ToList。如果您将查询移出return语句，它也会使事情变得更清楚。打破你的代码，你有效地得到了：

// We're not certain what type `db.Followusers` is, to be honest.
List<Foo> list = db.Followusers.Where(u => u.User1ID == currentUser.Id)
                               .ToList();
Followuser user = new Followuser() { User1ID = list };
return View(user);

你看到那个中间陈述没有意义吗？

我怀疑你只想要以下内容，假设db.Followusers真的像IQueryable<Followuser>：

// Single checks that there's exactly one record matching the predicate.
Followuser user = db.Followusers.Single(u => u.User1ID == currentUser.Id);
return View(user);

或者鉴于它现在相当简短：

return View(db.Followusers.Single(u => u.User1ID == currentUser.Id));

无法将类型'System.Collections.Generic.List'隐式转换为'string'

1 个答案: