Question

我需要能够在用户访问并且没有城市价值后编辑数据库中的用户。每件事都有效，可以编辑，但我无法编辑城市。

thisuser.FirstName = user.FirstName;
thisuser.LastName = user.LastName;
thisuser.UserName = user.UserName;
thisuser.Password = user.Password;
if (thisuser.Address != null)
{
   thisuser.Address.City = user.Address.City;
}
else if (thisuser.Address == null) !I need help here
{

}

Answer 1

如果这是使用某种ORM数据层，您只需创建对象，设置其值，然后将其添加到父对象。

thisuser.FirstName = user.FirstName;
thisuser.LastName = user.LastName;
thisuser.UserName = user.UserName;
thisuser.Password = user.Password;

if (thisuser.Address == null)
{
    thisuser.Address = new Address();   // Make sure this is the type 
                                        // that Address should be
                                        // This also assumes that Address is 1 to 1
}

thisuser.Address.City = user.Address.City;

如果地址属性是可以包含多个地址的导航属性，那么您需要在设置城市之前选择适当的地址，而不是如上所述的简单分配，您需要添加它顺序。

将null对象设置为值

1 个答案: