代码优先对象未正确实例化答案

【问题标题】：Code First Object not properly instantiating代码优先对象未正确实例化
【发布时间】：2011-10-13 20:19:49
【问题描述】：

我有一个从 activeentity 继承的班级部门

public class ActiveEntity : Entity, IActive
    {
        public ActiveEntity()
        {
            IsActive = true;
        }
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.None)]
        public Guid Id { get; set; }
        public bool IsActive { get; set; }
        [Timestamp, ScaffoldColumn(false), DatabaseGenerated(System.ComponentModel.DataAnnotations.DatabaseGeneratedOption.Computed)]
        public Byte[] Timestamp { get; set; }
        [ScaffoldColumn(false)]
        public string CreationUserId { get; set; }
        [ScaffoldColumn(false)]
        public string LastModifiedUserId { get; set; }
    }
    public class Department:ActiveEntity    
    {
        public Department()
        {
            this.Address = new DepartmentAddress();
        }
        [StringLength(9),MinLength(9),MaxLength(9)]
        public string Name { get; set; }

        public Guid ManagerId { get; set; }
        [UIHint("AjaxDropdown")]
        public User Manager { get; set; }
        public Guid? AddressId { get; set; }
        public DepartmentAddress Address { get; set; }

        public ICollection<OverheadRate> OverheadRates { get; set; }


    }

我只是使用注释没有 Fluent API。数据保存到数据 Sql Server 2008 就好了，但是地址对象永远不会被实例化，即使我有上下文使用包含

return c.Set<Department>().Include(d => d.Address).Include(d => d.Manager).Where(predicate);

返回数据我运行 sql profiler 然后运行查询它返回正确的数据。

有什么想法或建议吗？

【问题讨论】：

标签： entity-framework-4.1 ef-code-first

【解决方案1】：

删除在 Department 构造函数中实例化地址 (this.Address = new DepartmentAddress();)。在默认构造函数中实例化导航引用是邪恶的，并且有如下讨厌的副作用：

What would cause the Entity Framework to save an unloaded (but lazy loadable) reference over existing data?

EF 4.1 Code First: Why is EF not setting this navigation property?

【讨论】：