ruby-on-rails - has_many 关系的实际类别是什么？

Question

基础入门:

class User 
  has_many :programs, :through => :memberships
  has_many :memberships
end

class Program
end

class Membership
  belongs_to :user
  belongs_to :program
end

控制台:

User.new.save
Program.new.save
User.programs << Program.first

User.first.programs.class
# => Array
User.first.programs.methods.grep /where/
# => []
User.first.programs.where :id => 1
# => [#<Program id: 1>]
User.first.programs.where(:id => 1).class
# => ActiveRecord::Relation

所以问题是 User.first.programs，has_many 方法，似乎返回一个像 ActiveRecord::Relation 一样的结果，并接受像Relation，但 self 标识为 Array 并与类 Array 的实例共享其方法。

那么是什么给了？

Answer 1

这确实令人惊讶，不知道它是否是最好的解决方案，但至少它被记录在案(在 AssociationProxy 类中):

the association proxy in blog.posts has the object in blog as @owner, the collection of its posts as @target, and the @reflection object represents a :has_many macro.

This class has most of the basic instance methods removed, and delegates unknown methods to @target via method_missing. As a corner case, it even removes the class method and that’s why you get

blog.posts.class # => Array though the object behind blog.posts is not an Array, but an ActiveRecord::Associations::HasManyAssociation.