Association proxies in Active Record are middlemen between the object that holds the association, known as the @owner, and the actual associated object, known as the @target. The kind of association any proxy is about is available in @reflection. That’s an instance of the class ActiveRecord::Reflection::AssociationReflection.
For example, given
class Blog < ActiveRecord::Base has_many :posts end blog = Blog.first
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
The @target object is not loaded until needed. For example,
is computed directly through SQL and does not trigger by itself the instantiation of the actual post records.