Rails:has_many通过多态关联 - 这会有效吗？

Question

A Person可以有很多Events,每个都Event可以有一个多态Eventable记录.如何指定记录Person与Eventable记录之间的关系？

以下是我的模型:

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

主要问题涉及到Person班级:

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

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

或者我必须像这样拼写它们:

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

如果你看到一种更简单的方法来完成我所追求的目标,我会全都耳朵!:-)

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

这将使您能够这样做:

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