get all products of category and child categories (rails, awesome_nested_set)

Question

having an e-commerce application under development i am trying to get my head around the following problem: I have my categories realized through the awesome_nested_set plugin.

Answer 1

Extending charlysisto 's answer, when you are dealing with has_and_belongs_to_many categories, you will soon find out that the brute force perspective is quite slow... You need some kind of "middleware" to make it faster...

socjopata 's answer gives a good approach of how to improve this. So, you use the definition

def branch_ids
  self_and_descendants.map(&:id).uniq 
end

in your category.rb file (model).

Then, for example, in your controller (example with pagination):

@category = Category.find... # whatever
branches  = @category.branch_ids
@prodcats = ProductCategory.select('distinct product_id')
                           .where('category_id IN (?)',branches)
                           .order(:product_id)
                           .paginate(page: params[:page], :per_page => 25)
ids       = @prodcats.map(&:product_id)
@products = Product.where('id IN (?)', ids)

Finally, in your view, you will need a little "technique" in order to have pagination. You will paginate on @prodcats, not @products...

<%= will_paginate @prodcats %>
<% @products.each do |product| %>
    ....
<% end %>

This approach is way faster, WHEN DEALING WITH many_to_many, though not 100% politically correct, I must admit.