艺术家有许多活动(基本上是用户之间的交互的高速缓存):有没有办法来加载多态关联的关联?
class Activity < ActiveRecord::Base
belongs_to :receiver, :class_name => 'Artist', :foreign_key => :receiver_id #owns the stuff done "TO" him
belongs_to :link, :polymorphic => true
belongs_to :creator, :class_name => 'Artist', :foreign_key => :creator_id #person who initiated the activity
end
例如:
Activity.create(:receiver_id => author_id, :creator_id => artist_id, :link_id => id, :link_type => 'ArtRating')
我想为每位艺术家创建活动流页面,包括列表不同类型的事件,ArtRatings(喜欢,不喜欢的),收藏,继等
控制器看起来是这样的:
class ActivityStreamController < ApplicationController
def index
@activities = @artist.activities.includes([:link,:creator,:receiver]).order("id DESC").limit(30)
end
end
的DB调用正确急切地加载多态链接对象:
SELECT "activities".* FROM "activities" WHERE (("activities"."receiver_id" = 6 OR "activities"."creator_id" = 6)) ORDER BY id DESC LIMIT 30
ArtRating Load (0.5ms) SELECT "art_ratings".* FROM "art_ratings" WHERE "art_ratings"."id" IN (137, 136, 133, 130, 126, 125, 114, 104, 103, 95, 85, 80, 73, 64)
SELECT "follows".* FROM "follows" WHERE "follows"."id" IN (14, 10)
SELECT "favorites".* FROM "favorites" WHERE "favorites"."id" IN (25, 16, 14)
但是,当我显示每个ArtRating,我还需要引用的文章标题,这属于一个职位。在我看来,如果我这样做:
activity.link.post
它为每个art_rating的文章做一个单独的数据库调用。有没有办法热切地加载帖子?
更新的问题:
如果没有办法使用,实现职位的渴望加载“包括”语法,有没有办法做手工的预先加载查询自己和它注入@活动对象?
我在数据库日志中看到:
SELECT "art_ratings".* FROM "art_ratings" WHERE "art_ratings"."id" IN (137, 136, 133, 130, 126, 125, 114, 104, 103, 95, 85, 80, 73, 64)
有没有一种方法,我可以访问来自@activities IDS的这个列表对象?如果是这样,我可以做2个附加查询,其中1个获取该列表中的art_ratings.post_id(s),另一个查询将这些post_ids中的所有帖子选中。然后以某种方式将'post'结果注入到@activities中,以便在遍历集合时作为activity.link.post提供。可能?
这里有什么进展? – bogardon 2013-10-06 22:24:19
从我所了解的情况来看,你有一套应该作为链接附加到活动上的模型,我收集他们都至少共享一个关联,这是'post'。这些链接模型中是否有足够的共同点来使用[单表继承](http://apidock.com/rails/ActiveRecord/Base)并将所有表放在一个表中? – CMW 2013-10-25 13:03:36