activerecord - Rails best way to get previous and next active record object

Question

I need to get the previous and next active record objects with Rails. I did it, but don't know if it's the right way to do that.

What I've got:

Controller:

@product = Product.friendly.find(params[:id])

order_list = Product.select(:id).all.map(&:id)

current_position = order_list.index(@product.id)

@previous_product = @collection.products.find(order_list[current_position - 1]) if order_list[current_position - 1]
@next_product = @collection.products.find(order_list[current_position + 1]) if order_list[current_position + 1]

@previous_product ||= Product.last
@next_product ||= Product.first

product_model.rb

default_scope -> {order(:product_sub_group_id => :asc, :id => :asc)}

So, the problem here is that I need to go to my database and get all this ids to know who is the previous and the next.

Tried to use the gem order_query, but it did not work for me and I noted that it goes to the database and fetch all the records in that order, so, that's why I did the same but getting only the ids.

All the solutions that I found was with simple order querys. Order by id or something like a priority field.

Answer 1

Write these methods in your Product model:

class Product

  def next
    self.class.where("id > ?", id).first
  end

  def previous
    self.class.where("id < ?", id).last
  end

end

Now you can do in your controller:

@product = Product.friendly.find(params[:id])

@previous_product = @product.next
@next_product = @product.previous

Please try it, but its not tested. Thanks