我是 ASP.NET MVC4 的新手。这是我的问题:
我有两个表如下:
`Users(Username, Password, Email, RoleId)`
和
`Roles(Id, Name)`
哪个Users.RoleId
是外键引用Roles.Id
这是我的课:
[Table("Users")]
public class User
{
[Key, Required, DatabaseGenerated(DatabaseGeneratedOption.None)]
[StringLength(20)]
public string Username { get; set; }
[StringLength(32), Required]
public string Password { get; set; }
[StringLength(70), Required]
public string Email { get; set; }
public int RoleId { get; set; }
public virtual Role Role { get; set; }
}
[Table("Roles")]
public class Role
{
public Role()
{
Users = new HashSet<User>();
}
[Key, DatabaseGenerated(DatabaseGeneratedOption.Computed)]
public int Id { get; set; }
[StringLength(30)]
public string Name { get; set; }
public virtual ICollection<User> Users { get; set; }
}
public class Database : DbContext
{
public Database()
: base("WebstoreDbConnectionString")
{
}
public DbSet<User> Users { get; set; }
public DbSet<Role> Roles { get; set; }
}
现在,我可以选择我的数据库中的所有用户:
using (var db = new Database())
{
ViewBag.Users = db.Users.ToList();
}
并在视图中显示:
@foreach(var user in ViewBag.Users) {
<p>@user.Username | @user.Password</p>
}
但是声明:@user.Role.Name
给我一个错误:
The ObjectContext instance has been disposed and can no longer be used for operations that require a connection.
是什么导致了问题以及如何解决这个问题?