Asp.net mvc 4 我的模型对于ApplicationUser是空的

我有模特儿

 public class UserToRolesModel
{
    public List<ApplicationUser> userList { get; set; }
    public List<Microsoft.AspNet.Identity.EntityFramework.IdentityRole> rolesList { get; set; }

    [Required]
    public List<Microsoft.AspNet.Identity.EntityFramework.IdentityRole> selectedRoles { get; set; }
    [Required]
    public List<ApplicationUser> selectedUsers { get; set; }

}

我得到的模型是空的。我的职位是

[HttpPost]
    public ActionResult SaveUserRoles(UserToRolesModel usersroles)
    {
        foreach(var user in usersroles.selectedUsers)
        {
            var userExistingRoles = context.Roles;
        }
        return View(usersroles);
    }

get正在正确绑定数据

public ActionResult AddUserToRole()
    {
        var model = new UserToRolesModel();
        var users = context.Users.ToList();
        model.userList = users;
        model.rolesList = context.Roles.ToList();
        return View(model);
    }

之前我遇到了一个问题，我使用模型来处理局部变量，这导致了同样的问题。但我不认为这里有什么问题

public ActionResult AddUserToRole()
    {
        var model = new UserToRolesModel();
        var users = context.Users.ToList();
        model.userList = users;
        model.rolesList = context.Roles.ToList();
        return View(model);
    }