Question

我有一个我在控制器中使用的模型属性RegimeItemID。但是，当我试图调用它时，它会给出一个它不存在的错误。我做错了什么？

控制器

public ActionResult ExerciseIndex(int? id, UserExerciseViewModel vmodel)
        {
            User user = db.Users.Find(id);
            //user.RegimeItems = ChosenExercises();

            UserExerciseViewModel model = new UserExerciseViewModel { AvailableExercises = GetAllExercises(), RequestedExercises = ChosenExercises(user, vmodel) };
            //user.RegimeItems = db.RegimeItems.Find(model.SelectedExercise);
            user.RegimeItems = model.RequestedExercises;
            return View(model);
        }

private List<RegimeItem> ChosenExercises(User user, UserExerciseViewModel model)//RegimeItem regimeItem)//User user, RegimeItem regimeItem)
        {
            return db.Users.Where(r => r.RegimeItems.RegimeItemID == user.UserID).ToList();
        }

模型

 public class User
    {
        public int UserID { get; set; }
        public ICollection<RegimeItem> RegimeItems { get; set; }
        public User()
        {
            this.RegimeItems = new List<RegimeItem>();
        } 
    }
    public class RegimeItem
    {
        public int RegimeItemID { get; set; }
        public Exercise RegimeExercise { get; set; }
    }

视图模型

public class UserExerciseViewModel
{
    public List<Exercise> AvailableExercises { get; set; }
    public List<RegimeItem> RequestedExercises { get; set; }
    public int? SelectedExercise { get; set; }
    public int[] AvailableSelected { get; set; }
    public int[] RequestedSelected { get; set; }
    public string SavedRequested { get; set; }
}

我收到错误：

'System.Collections.Generic.ICollection<Project.Model.RegimeItem>' does not contain a definition for 'RegimeItemID' and no extension method 'RegimeItemID' accepting a first argument of type 'System.Collections.Generic.ICollection<Project.Model.RegimeItem>' could be found (are you missing a using directive or an assembly reference?)

我在控制器的这一行上得到它：

return db.Users.Where(r => r.RegimeItems.RegimeItemID == user.UserID).ToList();

Answer 1

RegimeItems是RegimeItem元素的集合 - 它不是单个元素，因此它没有单个ID。< / p>

听起来你可能想要这样的东西：

return db.Users
         .Where(r => r.RegimeItems.Any(ri => ri.RegimeItemID == user.UserID))
         .ToList();

这将找到具有任何政权项目的用户，其政权项目ID等于其用户ID。现在还不是很清楚这是否是明智的查询 - 为什么政权项目ID等于用户ID？它也没有正确的返回类型 - 这将返回User s的列表，而不是RegimeItem s。

你似乎更想要这样的东西：

return db.Users
         .Where(u => u.UserID == user.UserID)
         .SelectMany(u => u.RegimeItems)
         .ToList();

或者可能：

return db.Users
         .Where(u => u.UserID == user.UserID)
         .Single()
         .RegimeItems
         .ToList();

（您应该查看每种情况下涉及的查询。）

为什么我被告知我的模型属性（id）不存在，什么时候存在？

1 个答案: