Calculate what page a model is on using kaminari and mongoid

Question

I need to calculate what page a comment is on so I can create a direct link to it. I'm using kaminari pagination with monogid. On kaminari's wiki they have a solution on how to do it with activerecord but I'm not sure the best way to translate that into mongoid.

Answer 1

If you are using Mongoid 3, this method does the job:

class User
  include Mongoid::Document

  ...

  def page_num(options = {})
    field = options[:by] || :_id
    order = options[:order] || :asc
    per   = options[:per] || self.class.default_per_page

    operator = (order == :asc) ? field.to_sym.lte : field.to_sym.gte
    (self.class.where(operator => read_attribute(field)).order_by("#{field} #{order}").count.to_f / per).ceil
  end

  ...
end

Hope this helps.

Answer 2

Here is a stripped down version that I ended up coming up with.

def page_num
  number_before = self.class.where(recipe_id: recipe.id).gte(created_at: created_at).count.to_f
  number_on_page = self.class.default_per_page
  (number_before / number_on_page).ceil
end