1         /// <summary>
 2         /// 只更新storedAddress数据中的DefaultAddress字段,更新为false
 3         /// 将默认地址改为不是默认地址
 4         /// </summary>
 5         /// <param name="storedAddress">地址信息</param>
 6         public void Update(StoredAddress storedAddress)
 7         {
 8             StoredAddress s = new StoredAddress { StoredAddressID = storedAddress.StoredAddressID };
 9             s.DefaultAddress = true;
10
11             _context.StoredAddresses.Attach(s);
12
13             s.DefaultAddress = false;
14
15             _context.SaveChanges();
16             _context.Detach(s);
17         }

 1          /// <summary>
 2         /// 只更新storedAddress数据中的DefaultAddress字段,更新为false
 3         /// 将默认地址改为不是默认地址
 4         /// </summary>
 5         /// <param name="storedAddress">地址信息</param>
 6         public void UpdateStoredAddressDefaultAddress(StoredAddress storedAddress)
 7         {
 8             //先撤销跟踪
 9             _context.Detach(storedAddress);
10
11             StoredAddress s = new StoredAddress { StoredAddressID = storedAddress.StoredAddressID };
12             s.DefaultAddress = true;
13
14             _context.StoredAddresses.Attach(s);
15
16             s.DefaultAddress = false;
17
18             _context.SaveChanges();
19             _context.Detach(s);
20         }

 1  public static bool IsAttached(this AllureContext context, object entity)
 2         {
 3             if (entity == null)
 4             {
 5                 throw new ArgumentNullException("entity");
 6             }
 7             ObjectStateEntry entry;
 8             if (context.ObjectStateManager.TryGetObjectStateEntry(entity, out entry))
 9             {
10                 return (entry.State != System.Data.EntityState.Detached);
11             }
12             return false;
13         }

 1         /// 只更新storedAddress数据中的DefaultAddress字段,更新为false
 2         /// 将默认地址改为不是默认地址
 3         /// </summary>
 4         /// <param name="id">需要修改的对象的id</param>
 5         public void Update(int id)
 6         {
 7
 8             StoredAddress s = new StoredAddress { StoredAddressID = id };
 9             s.DefaultAddress = true;
10
11             _context.StoredAddresses.Attach(s);
12
13             s.DefaultAddress = false;
14
15             _context.SaveChanges();
16             _context.Detach(s);
17         }

 1         /// 只更新storedAddress数据中的DefaultAddress字段,更新为false
 2         /// 将默认地址改为不是默认地址
 3         /// </summary>
 4         /// <param name="id">需要修改的对象的id</param>
 5         public void Update(int id)
 6         {
 7
 8             StoredAddress s = new StoredAddress { StoredAddressID = id };
 9
10             object originalItem = null;
11             System.Data.EntityKey key = _context.CreateEntityKey("StoredAddresses", s);
12             if (_context.TryGetObjectByKey(key, out originalItem))
13             {
14                 _context.Detach(originalItem);
15             }
16
17              s.DefaultAddress = true;
18
19              _context.StoredAddresses.Attach(s);
20
21              s.DefaultAddress = false;
22
23              _context.SaveChanges();
24              _context.Detach(s);
25         }

我们通过EntityKey来获得这个对象，然后Detach这个对象，随后再Attach我们new的对象s，就可以修改数据库了。此方法中要注意CreateEntityKey（）的用法，第一个参数entitySetName，注意名称要和 Navigation Properties的名称一样，具体详见http://msdn.microsoft.com/en-us/library/system.data.objects.objectcontext.createentitykey.aspx

好了，我们的修改已经完成。