导航属性查询出来为空

Question

我添加了3张表 User、Role、UserRole(User和Role的中间表)

1.添加员工

 public ActionResult Add(User user)
        {
            if (ModelState.IsValid)
            {
                var entity = db.Users.FirstOrDefault(p => p.No == user.No);//No为主键
                if (entity != null)
                {
                    return Content("该员工已存在");
                }
                db.Users.Add(user);
                db.SaveChanges();
                return Content("addOk");
            }
            return Content("验证失败");
        }

2.添加角色

  public ActionResult Add(RoleModel model)
        {
            if (ModelState.IsValid)
            {
                Role role = new Role();
                role.No = model.No;//No为主键
                role.Name = model.Name;
                role.Makings = model.Makings;
                role.DutyReq = model.DutyReq;
                role.CreateTime = DateTime.Now;
                db.Roles.Add(role);
                db.SaveChanges();
                return Content("ok");
            }
            return Content("falair");

3，添加中间表数据

 public ActionResult AddUserRole(string roleNo, string userNo)
        {
            UserRole userRole = new UserRole();主键为Id
            userRole.RoleNo = roleNo;//外键
            userRole.UserNo = userNo;//外键
            db.UserRoles.Add(userRole);
            db.SaveChanges();
            return Content("添加成功");
        }

当我使用如下语句查询时

  var roles = db.Roles.Include("UserRoles").ToList();

roles变量里面的导航属性UserRoles为空

Answer 1

加了Map没有，告诉EF, Roles和UserRoles怎么对应

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http://feiyun0112.cnblogs.com/

Answer 2

加了Map没有，告诉EF, Roles和UserRoles怎么对应

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没Map 直接加的一个外键

Role类
[ForeignKey("RoleNo")]
public List<UserRole> UserRoles { get; set; }


UserRole类
public Role Role { get; set; }

Answer 3

你好，

看上去像是lazy loading的问题。默认情况下lazy loading是打开的，所以外键对应的内容是null。请尝试在初始化完context对象后设置lazy loading为false后，在试试能不能读出内容。

db.Configuration.LazyLoadingEnabled = false;

关于lazy loading更多请看： https://msdn.microsoft.com/en-us/data/jj574232.aspx#lazy

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