ruby-on-rails - rails : has_many through with polymorphic association - will this work?

Question

一个人可以有许多事件，每个事件可以有一个多态Eventable记录。如何指定 Person 和 Eventable 记录之间的关系？

这是我拥有的模型:

class Event < ActiveRecord::Base
  belongs_to :person
  belongs_to :eventable, :polymorphic => true
end

class Meal < ActiveRecord::Base
  has_one :event, :as => eventable
end

class Workout < ActiveRecord::Base
  has_one :event, :as => eventable
end

主要问题涉及 Person 类:

class Person < ActiveRecord::Base
  has_many :events
  has_many :eventables, :through => :events  # is this correct???
end

我是否像上面那样说has_many :eventables, :through => :events？

或者我必须像这样把它们全部拼写出来:

has_many :meals, :through => :events
has_many :workouts, :through => :events

如果您发现一种更简单的方法来完成我所追求的目标，我洗耳恭听! :-)

Answer 1

你必须做:

class Person < ActiveRecord::Base
  has_many :events
  has_many :meals, :through => :events, :source => :eventable,
    :source_type => "Meal"
  has_many :workouts, :through => :events, :source => :eventable,
    :source_type => "Workout"
end

这将使您能够执行以下操作:

p = Person.find(1)

# get a person's meals
p.meals.each do |m|
  puts m
end

# get a person's workouts
p.workouts.each do |w|
  puts w
end

# get all types of events for the person
p.events.each do |e|
  puts e.eventable
end