Convert an ActiveRecord model into a hash structure with all associations.

associations.rb

class ActiveRecord::Base
	def self.associations(exclude = [])
		classes = Hash[reflect_on_all_associations.map do |association|
			if (association.klass rescue nil)
				association.as_json.values_at("name", "klass")
			end
		end.compact]

		Hash[classes.map do |assoc_name, klass|
			assocs = nil
			assocs = klass.associations(exclude + [klass]) unless exclude.include? klass
			[assoc_name, assocs]
		end]
	end
end

class Hash
	def keyify(key, object = self)
		return object unless object.is_a? Hash
		{ key => Hash[object.map do |k, v|
			[k, keyify(key, v)]
		end] }
	end
end
 
# simple example
Model.first.as_json(Model.associations.keyify(:include))
 
# previous example has terrible performance.
# objects should be eager-loaded.
assocs = Model.associations
Model.includes(assocs).first.as_json(assocs.keyify(:include))