Rails如何在保存后更新列？
我想为我的费率操作创建一个after_save方法。 它会将rating_score / ratings分开并更新列评级。
class KonkurrancersController < ApplicationController def rate @konkurrancer = Konkurrancer.find(params[:id]) @container = "Konkurrancer"+@konkurrancer.id.to_s @konkurrancer.rating_score += params[:vind][:rating].to_i @konkurrancer.ratings += 1 @konkurrancer.save respond_to do |format| format.js end end end 这是我的模特：
class Konkurrancer rating) end end
我的rails日志：
Started POST "/konkurrancers/rate/46" for 127.0.0.1 at 2011-04-26 23:40:56 +0200 Processing by KonkurrancersController#rate as */* Parameters: {"utf8"=>"Ô£ô", "authenticity_token"=>"MACFM37hX4S6XA9vryn7gtfl21P vcaPBSiKDI8mfurg=", "vind"=>{"rating"=>"4"}, "id"=>"46"} ←[1m←[36mKonkurrancer Load (1.0ms)←[0m ←[1mSELECT `konkurrancers`.* FROM `kon kurrancers`←[0m ←[1m←[35mCACHE (0.0ms)←[0m SELECT `konkurrancers`.* FROM `konkurrancers` ←[1m←[36mCACHE (0.0ms)←[0m ←[1mSELECT `konkurrancers`.* FROM `konkurrancers`← [0m ←[1m←[35mKonkurrancer Load (1.0ms)←[0m SELECT `konkurrancers`.* FROM `konkurr ancers` WHERE (`konkurrancers`.`cached_slug` = '46') LIMIT 1 ←[1m←[36mSQL (2.0ms)←[0m ←[1mSELECT sluggable_id FROM slugs WHERE ((slugs.slu ggable_type = 'Konkurrancer' AND slugs.name = '46' AND slugs.sequence = 1))←[0m ←[1m←[35mKonkurrancer Load (1.0ms)←[0m SELECT `konkurrancers`.* FROM `konkurr ancers` WHERE (`konkurrancers`.`id` = 46) LIMIT 1 ←[1m←[36mSQL (0.0ms)←[0m ←[1mBEGIN←[0m ←[1m←[35mLink Load (1.0ms)←[0m SELECT `links`.* FROM `links` WHERE (`links`.k onkurrancer_id = 46) LIMIT 1 ←[1m←[36mSQL (0.0ms)←[0m ←[1mROLLBACK←[0m Rendered konkurrancers/_rating.html.erb (1.0ms) Rendered konkurrancers/rate.js.erb (22.0ms) Completed 200 OK in 606ms (Views: 286.0ms | ActiveRecord: 6.0ms)
我该怎么创造这个？
你想要的是一个回调。 您可以在Konkurrancer模型上创建after_save回调，该模型在为该模型调用save（）方法后触发。
例如：
class Konkurrancer < ActiveRecord::Base after_save :do_foobar private def do_foobar rating_score = self.rating_score ratings = self.ratings rating = (rating_score/ratings) self.update_attributes(:ratings => rating) end end
[编辑]您应该使用self ，因为您正在编辑的模型是模型本身。 测试它，并应用必要的逻辑/实现。
有关详细信息，请查看本指南 。
希望有所帮助！
after_save回调中的任何update_attribute都将导致Rails3 +中的递归。 应该做的是：
after_save :updater # Awesome Ruby code # ... # ... private def updater self.update_column(:column_name, new_value) # This will skip validation gracefully. end
不确定为什么人们正在推翻错误答案并低估正确答案。
Zakelfassi是正确的，而基督教法齐尼对于Rails 3及以上版本是错误的。 如果在保存回调中执行#update_attributes，则会进入无限递归。 你想按照他的例子做#update_column。
亲自尝试，你会看到。
@konkurrancer.update_attributes :ratings=>'updated value'
看到这个after_save方法