Utility methods for pagination page and per page that make sure you'll always have a valid number.

Use them your controllers (recommended) or model or anywhere where you process page info.

PageNumber provides 3 methods:

• page(n)/__page__(n) (defaults to 1)
• page!(n)/__page__!(n) (raises PageNumber::PageInvalid instead of returning default)
• per_page(n)/__per_page__(n) (defaults to 10)

To use, include or extend the PageNumber module:

require "page_number"

class BaseController
  include PageNumber
end

class SubController < BaseController
  def index
    User.all(:page => page(params[:page]), :per_page => per_page(params[:per_page]))
  end
end

To have better control over how page and per_page work you can define one or more of the following methods:

class BaseController
  include PageNumber

  # These are all optional
  protected

  def page_sizes
    [ 25, 50, 100 ]
  end

  def default_per_page
    20
  end

  def default_page
    2
  end

  def max_page_number
    # who knows!?
  end

If you use PageNumber in a class context in model that uses will_paginate and you subclasses that model you may receive the following error:

ArgumentError: wrong number of arguments (given 0, expected 1)
	from /Users/sshaw/code/ruby/page_number/lib/page_number.rb:53:in `per_page'
   	from /Users/sshaw/.rvm/gems/ruby-2.3.7/gems/will_paginate-3.1.6/lib/will_paginate/per_page.rb:18:in `inherited'
    ...

This is because will_paginate is expecting its per_page method.

One way to avoid this:

class YourModel < ApplicationRecord
  Pager = Class.new { extend PageNumber }
end

Now instead of calling PageNumber's per_page as is you call via the Pager class: Pager.per_page

Skye Shaw [skye.shaw AT gmail.com]

Released under the MIT License: http://www.opensource.org/licenses/MIT