Module: ConcernsOnRails::Controllers::Paginatable

Extended by:
ActiveSupport::Concern
Defined in:
lib/concerns_on_rails/controllers/paginatable.rb

Overview

Adds simple offset-based pagination to a controller, with no runtime dependency on Kaminari/will_paginate. Use it like:

class ArticlesController < ApplicationController
  include ConcernsOnRails::Controllers::Paginatable
  paginate_by per_page: 25, max_per_page: 200   # optional

  def index
    render json: paginated(Article.all)
  end
end

Constant Summary collapse

DEFAULT_PER_PAGE = 
25
DEFAULT_MAX_PER_PAGE = 
200

Instance Method Summary collapse

Instance Method Details

#paginated(relation) ⇒ Object

Apply pagination to a relation and set the standard response headers. Returns the paginated relation. Safe on empty relations.



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# File 'lib/concerns_on_rails/controllers/paginatable.rb', line 39

def paginated(relation)
  page = pagination_page
  per_page = pagination_per_page
  offset = (page - 1) * per_page

  counted = relation.except(:order, :limit, :offset).count
  # `.count` on a grouped relation returns a Hash (group => count); for
  # offset pagination the meaningful total is the number of groups.
  total = counted.is_a?(Hash) ? counted.length : counted
  total_pages = per_page.positive? ? (total.to_f / per_page).ceil : 0

  records = relation.limit(per_page).offset(offset)

  set_pagination_headers(total: total, page: page, per_page: per_page, total_pages: total_pages)
  records
end

#pagination_meta(relation) ⇒ Object

Pagination metadata for a relation WITHOUT applying limit/offset — handy for body-based pagination (compose with Respondable’s ‘meta:`).



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# File 'lib/concerns_on_rails/controllers/paginatable.rb', line 58

def pagination_meta(relation)
  page = pagination_page
  per_page = pagination_per_page
  counted = relation.except(:order, :limit, :offset).count
  total = counted.is_a?(Hash) ? counted.length : counted
  {
    total: total,
    page: page,
    per_page: per_page,
    total_pages: per_page.positive? ? (total.to_f / per_page).ceil : 0
  }
end