has_many :through, :source, :source_type 返回空数组

Question

我有一些 Manager 和 SoccerTeam 模型。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：

ma​​nager.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：

• manager.reviews 和 soccer_team.comments 中的 Comment 对象
• manager.observed_teams 中的 SoccerTeam 对象
• soccer_team.observers 中的 Manager 对象

虽然第一点和第三点一切正常，但当我调用manager.observed_teams 时，我总是得到一个空数组。要真正获得经理评论过的足球队名单，我需要使用：

manager.reviews.collect{ |review| Kernel.const_get(review.commentable_type).find(review.commentable_id) if review.commentable_type == "SoccerTeam" }

这是丑陋的。我希望简单的manager.observed_teams 可以工作……为什么不行？

编辑

我更进一步了解了它为什么不起作用。其实生成的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 和:as 的启发式尝试并没有解决问题！）。

Answer 1

我认为您只是为 observed_teams 使用了错误的关联。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"

还有，

has_many :reviews, :class_name => :comment, 
  :foreign_key => :author_id, :dependent => :destroy

:comment 应该是'Comment'

在

has_many :comments, :as => commentable, :dependent => :destroy

commmentable 应该是:commmentable