I have a user model that has many carts
我有一个有很多购物车的用户模型
class User < ActiveRecord::Base
has_many :carts
If I update a cart:
如果我更新购物车:
User.last.carts.last.time_purchased = Time.now
Is there a way I can save the whole user model? Now, if I call
有办法保存整个用户模型吗?现在,如果我的电话
User.last.save
The cart that I modified is not saved.
我修改的购物车没有保存。
User.last.carts.last.save
Does save the cart.
是否保存购物车。
Is there a way to save all updated attributes of a model?
是否有方法保存模型的所有更新属性?
Thanks
谢谢
2 个解决方案
#1
2
Saving a model will save any of its associations, but the reason this isn't working for you is because you are re-fetching the User model instead of modifying and saving the same instance.
保存一个模型将会保存它的任何关联，但是这并不适合您，因为您正在重新获取用户模型，而不是修改和保存相同的实例。
user = User.last
user.carts.last.time_purchased = Time.now
user.save
Saving the user should also save the associated cart.
保存用户也应该保存相关的购物车。
#2
2
This is because you are fetching a copy of the cart, modifying it, then fetching another copy of the cart and saving that.
这是因为您正在获取购物车的副本，修改它，然后获取购物车的另一个副本并保存它。
You should save the cart in a variable, then apply the save on that. For example:
您应该将购物车保存在一个变量中，然后在该变量上应用save。例如:
cart = User.last.carts.last
cart.time_purchased = Time.now
cart.save
Alternatively, you can use update_attribute, like this:
或者，也可以使用update_attribute，如下所示:
User.last.carts.last.update_attribute(:time_purchased, Time.now)
#1
2
Saving a model will save any of its associations, but the reason this isn't working for you is because you are re-fetching the User model instead of modifying and saving the same instance.
保存一个模型将会保存它的任何关联，但是这并不适合您，因为您正在重新获取用户模型，而不是修改和保存相同的实例。
user = User.last
user.carts.last.time_purchased = Time.now
user.save
Saving the user should also save the associated cart.
保存用户也应该保存相关的购物车。
#2
2
This is because you are fetching a copy of the cart, modifying it, then fetching another copy of the cart and saving that.
这是因为您正在获取购物车的副本，修改它，然后获取购物车的另一个副本并保存它。
You should save the cart in a variable, then apply the save on that. For example:
您应该将购物车保存在一个变量中，然后在该变量上应用save。例如:
cart = User.last.carts.last
cart.time_purchased = Time.now
cart.save
Alternatively, you can use update_attribute, like this:
或者，也可以使用update_attribute，如下所示:
User.last.carts.last.update_attribute(:time_purchased, Time.now)