我有一些Manager
和SoccerTeam
型号。一名经理“拥有”许多足球队;经理也可以评论足球队,也可以评论其他经理:
manager.rb
# Soccer teams the manager owns
has_many :soccer_teams, :dependent => :restrict
# Comments the manager has made on soccer teams or other managers
has_many :reviews, :class_name => "Comment", :foreign_key => :author_id, :dependent => :destroy
# Comments the manager has received by other managers
has_many :comments, :as => :commentable, :dependent => :destroy
# Soccer teams that have received a comment by the manager
has_many :observed_teams, :through => :comments, :source => :commentable, :source_type => "SoccerTeam"
soccer_team.rb
# The manager that owns the team
belongs_to :manager
# Comments received by managers
has_many :comments, :as => :commentable, :dependent => :destroy
# Managers that have reviewed the team
has_many :observers, :through => :comments, :source => :author, :class_name => "Manager"
comment.rb
belongs_to :commentable, :polymorphic => true
belongs_to :author, :class_name => Manager
现在,如果我有一位经理对SoccerTeam发表评论,我希望找到:
Comment
和manager.reviews
soccer_team.comments
个对象
SoccerTeam
manager.observed_teams
个对象
Manager
soccer_team.observers
个对象
虽然一切都适用于第一点和第三点,但当我调用manager.observed_teams
时,我总是获得一个空数组。要真正获得经理评论我需要使用的足球队列表:
manager.reviews.collect{ |review| Kernel.const_get(review.commentable_type).find(review.commentable_id) if review.commentable_type == "SoccerTeam" }
哪个很难看。我希望简单的manager.observed_teams
可以工作......为什么不工作?
修改
我更进一步了解它为什么不起作用。实际上,生成的SQL是:
SELECT "soccer_teams".* FROM "soccer_teams" INNER JOIN "comments" ON "soccer_teams".id = "soccer_teams".commentable_id AND "comments".commentable_type = 'SoccerTeam' WHERE (("comments".commentable_id = 1) AND ("comments".commentable_type = 'Manager'))
虽然我希望它是:
SELECT "soccer_teams".* FROM "soccer_teams" INNER JOIN "comments" ON "soccer_teams".id = "comments".commentable_id AND "comments".commentable_type = 'SoccerTeam' WHERE ("comments".author_id = 1)
所以问题很简单:如何获取该查询? (正如预期的那样,使用:foreign_key
ans :as
进行启发式尝试并未解决问题!)。
答案 0 :(得分:13)
我认为你只是使用observed_teams
的错误关联。而不是
has_many :observed_teams, :through => :comments,
:source => :commentable, :source_type => "SoccerTeam"
试试这个:
has_many :observed_teams, :through => :reviews,
:source => :commentable, :source_type => "SoccerTeam"
同样在,
has_many :reviews, :class_name => :comment,
:foreign_key => :author_id, :dependent => :destroy
:comment
应为'Comment'
并在
has_many :comments, :as => commentable, :dependent => :destroy
commmentable
应为:commmentable