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

Question

On my website I am trying to return a list which shows the users that the current user is following but I keep on recieving the error Cannot implicitly convert type 'System.Collections.Generic.List' to 'string'

Any help would be greatful

User Controller

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()
                       });

        }

Followuser model

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

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


    }

Answer 1

You're calling ToList for no obvious reason. It would also make things clearer if you moved the query out of the return statement. Breaking your code down, you've effectively got:

// 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);

Do you see how that middle statement doesn't make sense?

I suspect you just want the following, assuming that db.Followusers is really something like 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);

Or given that it's now fairly short and simple:

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