从活动记录关系中提取对象的最佳方法

Question

What would be the best way to iterate through an active relation. Let's say I have an active relation object returned. I want to break it down into the corresponding category of their parent. I have 12 categories for products, and I'm building 12 dropdowns!

Product belongs to category Product has many favorites User has_many :products, through: :favorites

Favorite.includes(:product).where('user_id = ?', current_user.id).each do |favorite|
...?...
end 

Answer 1

you could try something like:

grouped_favorites = Favorite.includes(:product => :category)
                            .where('user_id = ?', current_user.id)
                            .group_by {|favorite| favorite.product.category }

grouped_favorites.each do |category, favorites|
   favorites.each do |favorite|
     ...?...
   end
end