ActiveRecord before_update 回调理解

Question

我理解正确吗，如果我执行

model = Model.create(some_attr: "attr_value")

model.update(some_attr: "new_attr_value")

对于模型我有

before_update :before_update_callback

def before_update_callback
  some_attr
end

该回调将 return“new_attr_value”，因为内部 ruby 对象（变量“model”）在调用回调之前已更改。

Answer 1

是的。这正是将要发生的事情。

# Updates the attributes of the model from the passed-in hash and saves the
# record, all wrapped in a transaction. If the object is invalid, the saving
# will fail and false will be returned.
def update(attributes)
  # The following transaction covers any possible database side-effects of the
  # attributes assignment. For example, setting the IDs of a child collection.
  with_transaction_returning_status do
    assign_attributes(attributes)
    save
  end
end

参见：

ActiveRecord before_update 回调理解

ActiveRecord before_update callback understanding

activerecord

ruby-on-rails

callback