Question

I have a Rails 3 inhouse application which is used on:
19″ touch screen, 10″ iPads, 7″ Tablet

I am using will_paginate / kaminari for displaying lists of data.

But how can I configure how many items per page it should display depending on the screen size?

e.g. 20 lines for a 19″ display, 11 lines for a 10″ display, 8 lines for a 7″ display

Answer 1

You might consider on the first request to your application passing via Ajax the relevant navigator and/or screen information and using that information to decide on the backend in Rails.

To get browser/OS information, see Javascript’s navigator object and to get information about the screen dimensions, check Javascript’s screen object.

Your Ajax controller action could store JSON versions of the navigator/screen information to session and a before_filter in ApplicationController could be used to set @per_page for use throughout your application’s paginators.

before_filter do
  @per_page = 11 if !session[:navigator][:userAgent].match(/iPad/).nil?
  @per_page = 8  if !session[:navigator][:userAgent].match(/Android/).nil? && session[:screen][:width] < 1000
  # ...
end

You’d then pass @per_page to kaminari’s pager.