Query with alternating orders on ruby on rails

Question

I have this code to query patients:

Patients.order(params[:sort])

how can I implement this so that each time this query will be executed the results are in an alternating order thus: (ascending -> descending -> ascending -> ...) ?

This code is implemented on a Controller on a Ruby on Rails application.

Answer 1

To implement this, you should store some key anywhere, right? Storing it in a database is not a good idea, because it's a +1 extra select and +1 extra update query for each page loading. If we store it anywhere on the server, eg, in Redis , it will be global for all users, or we will have to store as many keys as many users we have. So why not to store it on the side of a user? I think the best way is to store it in cookies and invert the key each time after the query. Or in the session.

sort_order = cookies[:sort_order] || 'asc'

Patients.order("#{params[:sort]} #{sort_order}")

cookies[:inverted_sort_order] = sort_order == 'asc' ? 'desc' : 'asc'

Answer 2

You can implemente this behaviour with a class variable, that increments every time you go to a particular action in your controller

#In your controller
@@hit_number ||= 0                  #This will set your hit_number the first time
@@hit_number = @@hit_number + 1     #Increment your hit_number

if (@@hit_number%2) == 0            #Switch for :asc or :desc 
  @my_order = :asc
else
  @my_order = :desc
end

@patients = Patients.order(name: @my_order)

And then, in your view the order will change every time it loads the view.

Note: This is not the best way to achieve this, but it is the easiest way for someone new to rails in my opinion.