Rails 4、has_many関連 - 関連付けられたオブジェクトを見つける

Question

なぜItem.where(category: x)が私にとってうまくいかないのだろうか。このステートメントは、カテゴリxの下に分類されたすべてのアイテムを返すと期待しています。私の団体の下をご覧ください：

class Category < ActiveRecord::Base 
    has_many :categorizations 
    has_many :items, :through => :categorizations 
end 

class Item < ActiveRecord::Base 
    has_many :categorizations 
    has_many :categories, :through => :categorizations 
end 

class Categorization < ActiveRecord::Base 
    belongs_to :item 
    belongs_to :category 
end 

Category.find(1).itemsこのカテゴリのすべての商品を返します。以下、私のポイントをさらに詳しく示すbyebugコンソールの出力を見てください。生成されたSQlがItemテーブル内のカテゴリ列を探しているようです - もちろん存在しません。何か案は？

Item.joins(:categories).where(categories: {id: 1}) 

私はこれを行うためのより良い方法を見つけるために、まだだ：

1: class ItemsController < ApplicationController 
    2: # Returns full list of items 
    3: def index 
    4:  @items = Item.all 
    5:  byebug 
=> 6: end 
    7: 

(byebug) Item.where(category: 1) 
    Item Load (0.6ms) SELECT "items".* FROM "items" WHERE "items"."category" = 1 
#<Item::ActiveRecord_Relation:0x007fb5d1a37f08> 
(byebug) Category.find(1).items 
    Category Load (0.7ms) SELECT "categories".* FROM "categories" WHERE "categories"."id" = $1 LIMIT 1 [["id", 1]] 
    Item Load (1.7ms) SELECT "items".* FROM "items" INNER JOIN "categorizations" ON "items"."id" = "categorizations"."item_id" WHERE "categorizations"."category_id" = $1 [["category_id", 1]] 
#<ActiveRecord::Associations::CollectionProxy [#<Item id: 1, title: "Gorgeous Cotton Pants", description: "Dolor dicta suscipit aut cupiditate quia officiis ...", price: 73960, status: 0, published_date: "2016-07-14 05:35:49", created_at: "2016-07-17 05:15:07", updated_at: "2016-07-17 05:15:07", seller_id: 1>, #<Item id: 5, title: "Sleek Marble Shoes", description: "Qui mollitia corporis qui placeat. Reiciendis ea s...", price: 35146, status: 0, published_date: "2016-07-14 05:45:02", created_at: "2016-07-17 05:15:07", updated_at: "2016-07-17 05:15:07", seller_id: 1>, #<Item id: 7, title: "Rustic Concrete Lamp", description: "Sit odio non exercitationem. Atque non sapiente vo...", price: 82016, status: 2, published_date: "2016-07-13 00:00:00", created_at: "2016-07-17 05:15:07", updated_at: "2016-07-17 05:15:07", seller_id: 1>, #<Item id: 10, title: "Awesome Wooden Table", description: "Possimus consequatur nulla. Quidem molestiae volup...", price: 59519, status: 2, published_date: "2016-07-09 00:00:00", created_at: "2016-07-17 05:15:07", updated_at: "2016-07-17 05:15:07", seller_id: 1>, #<Item id: 12, title: "Lightweight Concrete Bag", description: "Amet ullam assumenda eligendi consectetur quae. Bl...", price: 72081, status: 2, published_date: "2016-07-16 00:00:00", created_at: "2016-07-17 05:15:07", updated_at: "2016-07-17 05:15:07", seller_id: 2>, #<Item id: 13, title: "Mediocre Plastic Computer", description: "Excepturi modi est non qui iusto. Molestiae offici...", price: 94357, status: 2, published_date: "2016-07-15 00:00:00", created_at: "2016-07-17 05:15:07", updated_at: "2016-07-17 05:15:07", seller_id: 2>, #<Item id: 15, title: "Incredible Plastic Bag", description: "Vel voluptas ducimus soluta atque voluptatem eum. ...", price: 15661, status: 2, published_date: "2016-07-14 00:00:00", created_at: "2016-07-17 05:15:07", updated_at: "2016-07-17 05:15:07", seller_id: 2>, #<Item id: 16, title: "Lightweight Iron Watch", description: "Id sequi rerum dolor sit sunt nemo laborum. Omnis ...", price: 65306, status: 4, published_date: "2016-07-11 00:00:00", created_at: "2016-07-17 05:15:07", updated_at: "2016-07-17 05:15:07", seller_id: 1>, #<Item id: 17, title: "Rustic Linen Chair", description: "Explicabo qui ad nihil. Voluptatem placeat autem. ...", price: 39752, status: 4, published_date: "2016-07-04 00:00:00", created_at: "2016-07-17 05:15:07", updated_at: "2016-07-17 05:15:07", seller_id: 1>, #<Item id: 18, title: "Mediocre Copper Car", description: "Minus qui ut est non vero saepe. Qui sed quos et v...", price: 87765, status: 4, published_date: "2016-07-05 00:00:00", created_at: "2016-07-17 05:15:07", updated_at: "2016-07-17 05:15:07", seller_id: 1>]> 

Answer 1

私はhas_many throughに関連付けられたオブジェクトを取得するためのアプローチのような何かをすることだと思います。