skipping after_update callback(=)

ActiveRecord: Skipping callbacks like after_save or after_update

Active Records provides callbacks, which is great is you want to perform extra business logic after (or before) saving, creating or destroying an instance of that model.

However, there are situations where you can easily fall into the trap of creating an infinite loop.

class Beer < ActiveRecord::Base
  def after_save
    x = some_magic_method(self)
    update_attribute(:my_attribute, x)
  end
end

The above will give you a nice infinite loop (which doesn’t scale). It’s possible to update your model, without calling the callbacks and without resorting to SQL.

class Beer < ActiveRecord::Base
  def after_save
    x = some_magic_method(self)
    Beer.update_all("my_attribute = #{x}", { :id => self.id })
  end
end

This is a bit unconventional, but it works nicely. You can use all the following ActiveRecord methods to update your model without calling callbacks:
一下方法不会触发callback
    * decrement
    * decrement_counter
    * delete
    * delete_all
    * find_by_sql
    * increment
    * increment_counter
    * toggle
    * update_all
    * update_counters

An important warning: These methods don’t do all the nice SQL injection protection stuff you’re used to. In the example, the value of x will be inserted straight into the SQL. I recommend you only use these methods if you’re absolutely sure you’ve cleaned the values you’re inserting.
这些方法没有sql注入的保护，所以必须确保使用时是没有sql注入的。