Entity Framework 数据部分更新之Attach &&Detach

/// 只更新storedAddress数据中的DefaultAddress字段,更新为false  

/// 将默认地址改为不是默认地址  

/// </summary>

/// <param name="id">需要修改的对象的id</param>

public void Update(int id)  

{  

  StoredAddress s = new StoredAddress { StoredAddressID = id };  

  object originalItem = null; 

             System.Data.EntityKey key =  _context.CreateEntityKey("StoredAddresses", s); 

             if (_context.TryGetObjectByKey(key, out originalItem)) 
             { 

                 _context.Detach(originalItem); 

             } 

             s.DefaultAddress = true; 

          _context.StoredAddresses.Attach(s); 

            s.DefaultAddress = false; 

             _context.SaveChanges(); 

              _context.Detach(s);

}