Ruby on rails ActiveRecord复杂查询

我找不到最畅销的书。我有以下型号： 书

classbook

图书类别

class BooksCategory < ApplicationRecord
  belongs_to :category
  belongs_to :book
end

class-BooksCategory

类别

class Category < ApplicationRecord
  has_and_belongs_to_many :books
end

类别

订单项

class OrderItem < ApplicationRecord
  belongs_to :order
  belongs_to :book
end

class OrderItem

秩序

class Order < ApplicationRecord
  has_many :order_items, dependent: :destroy
  has_many :books, through: :order_items
end

类顺序

所以我需要从每个类别中找出最畅销的书。当订单状态为2或3时，书籍被视为已售出。我编写了下一个代码：

  def best_sellers
    books_ids = []

    Category.all.each do |category|
      temp_hash = OrderItem.joins(book: :books_categories)
        .where(books: { books_categories: { category: category } })
        .joins(:order).where(orders: { status: [2, 3] })
        .group(:book_id).sum(:quantity)

      books_ids << temp_hash.key(temp_hash.values.max)
    end

    Book.where(id: books_ids)
  end

def畅销书
书籍\u id=[]
Category.all.each do | Category|
temp\u hash=OrderItem.join（book:：books\u类别）
.where（图书：{books\u categories:{category:category}}）
.joins（：order）.where（orders:{status:[2,3]}）
.组（：账簿id）.总和（：数量）
图书标识
  def best_sellers
    books_ids = []

    Category.all.each do |category|
      temp_hash = OrderItem.joins(book: :books_categories)
        .where(books: { books_categories: { category: category } })
        .joins(:order).where(orders: { status: [2, 3] })
        .group(:book_id).sum(:quantity)

      books_ids << temp_hash.key(temp_hash.values.max)
    end

    Book.where(id: books_ids)
  end