Basic structure to build API endpoint for pd_resources (search)

1_pd_resource.rb

# app/models/pd_resource.rb
class PdResource < ActiveRecord::Base
  # ...
  SORT_OPTIONS = [:alpha, :popular]
  SORT_CLAUSES = {
    alpha: "pd_resources.title ASC",
    popular: "pd_resources.views DESC",
  }
  #...
end

2_pd_resources_controller.rb

# app/controllers/api/v1/pd_resources_controller.rb
class Api::V1::PdResourcesController < ApplicationController

  # GET "/api/v1/pd_resources"
  #
  # Params supported as query string:
  #   + query:       free text used as the search string to query Elastic Search.
  #   + pd_type[]:   array of pd type's ids to filter pd_resources by pd type.
  #   + language[]:  array of language's ids to filter pd_resources by language.
  #   + age_level[]: array of age_level's ids to filter pd_resources by age_level.
  #   + domain[]:    array of domain's ids to filter pd_resources by domain.
  #   + dimension[]: array of dimension's ids to filter pd_resources by dimension.
  #   + sort_by:     string that defines how results should be sorted: ['alpha', 'popular']. Defaults: 'alpha'
  #   + page:        page number used for pagination. Default: 1.
  #   + per_page:    number of items returned on each page. Default: 25.
  #

  def index
    filter   = build_es_filter(params)
    sorting  = calculate_sorting(params[:sort_by])
    page     = params[:page] || 1
    per_page = params[:page] || 25
    @pd_resources = PdResource.search(filter)
    @pd_resources.order(order).page(page).per_page(per_page)
  end


  private

  def build_es_filter(params)
    # TODO: logic to create the filter hash needed by Elastic Search
    # taking in count the following params:
    # => params[query]
    # => params[pd_type]
    # => params[language]
    # => params[age_level]
    # => params[domain]
    # => params[dimension]
  end

  def calculate_sorting_clause(sort_str)
    sort_option = PdResource::SORT_OPTIONS.include?(sort_str) ? sort_str : PdResource::SORT_OPTIONS.first
    PdResource::SORT_CLAUSES[sort_option]
  end

end

3_index.json.jbuilder

# app/views/api/v1/pd_resources/index.json.jbuilder
json.partial! 'pd_resource', collection: @pd_resources, as: :pd_resource