Rails filtering resource one to many through a joint table

I have the following resources:- restaurant- category- item- check item

Relationship:

class Restaurant < ActiveRecord::Base  has_many :items  has_many :categories  has_many :check_itemsclass Category < ActiveRecord::Base  belongs_to :restaurant  has_many :itemsclass Item < ActiveRecord::Base  belongs_to :restaurant  belongs_to :categoryclass CheckItem < ActiveRecord::Base  belongs_to :item

I need to filter all the check_items of a restaurant where category.uuid = '123123'

so I have my @restaurant.check_items. How do I join these together to basically implement this sql query:

SELECT * from checkitemINNER JOIN item ON(checkitem.item_id = item.id)INNER JOIN category ON(category.id = item.category_id)WHERE category.restaurant_id = 1 AND category.uuid = '123123'LIMIT 20;

I've tried with scope:

#already have my restaurant resource here with id 1@restaurant.check_items.by_item_category params[:category_uuid]

And in my models I would have:

class CheckItem < ActiveRecord::Base  ...  scope :by_item_category, -> value { joins(:item).by_category value }class Item < ActiveRecord::Base  ...  scope :by_category, -> value { joins(:category).where('%s.uuid = ?' % Category.table_name, value)}

Buut this doesn't seem to work