RESTful controller with filterrific integration

restful_controller.rb

module Api
  module V1
    # This is a module that provides a RESTful action for all API controllers.
    # Uses filterrific gem to filter records.
    # Uses will_paginate gem for pagination.
    module RestfulController
      extend ActiveSupport::Concern

      included do
        before_action :resource_model, only: [:index, :show, :create, :update, :destroy]
        before_action :resource_params, only: [:create, :update]

        def index
          @filterrific = initialize_filterrific(
            resource_model,
            params[:filterrific],
            default_filter_params: filter_default_scopes,
            available_filters: filter_scopes
          ) or return

          @resource_records = @filterrific.find.page(page_number).per_page(page_size)
          render json: @resource_records, meta: pagination_dict(@resource_records), status: :ok
        end

        def show
          @resource = resource_model.find(params[:id])
          if @resource
            render json: @resource, status: :ok
          else
            render json: {resource: @resource, message: "Resource not found", errors: @resource.errors.full_messages}, status: :not_found
          end
        end

        def create
          @resource = resource_model.new(resource_params)
          if @resource.save
            render json: @resource, status: :created
          else
            render json: {resource: @resource, message: "Resource not created", errors: @resource.errors.full_messages}, status: :unprocessable_entity
          end
        end

        def update
          @resource = resource_model.find(params[:id])
          if @resource.update(resource_params)
            render json: @resource, status: :ok
          else
            render json: {resource: @resource, message: "Resource not updated", errors: @resource.errors.full_messages}, status: :unprocessable_entity
          end
        end

        def destroy
          @resource = resource_model.find(params[:id])
          if @resource.destroy
            render json: {message: "Resource destroyed"}, status: :ok
          else
            render json: {resource: @resource, message: "Resource not destroyed", errors: @resource.errors.full_messages}, status: :unprocessable_entity
          end
        end
      end

      class NotOverriden < StandardError
        def initialize(arg)
          super arg.to_s
        end
      end

      # This is a hook method that returns the model class associated with the current controller.
      # @raise [NotOverriden] if the method is not overriden.
      # @return [Class] the model class associated with the current controller.
      def resource_model() = raise(NotOverriden.new("Pass the model class you want to use for this controller"))

      # This is a hook method that permits the model params
      # @raise [NotOverriden] if the method is not overriden.
      # @return [ActionController::Parameters] the permitted paramenters
      def resource_params() = raise(NotOverriden.new("You must define the permitted parameter for the current model"))

      # This is a hook method that returns an array of symbols with the names of scopes of the current model.
      # That we can use to filter the data
      # @raise [NotOverriden] if the method is not overriden.
      # @return [Array<Symbol>] the names of scopes of the current model.
      def filter_scopes() = raise(NotOverriden.new("You must define the scopes that can be used for filtering"))

      # This is a hook method that returns an array of symbols with the names of default scopes of the current model.
      # That will filter data by default
      # @raise [NotOverriden] if the method is not overriden.
      # @return [Hash<Symbol>] the names of default scopes of the current model.
      def filter_default_scopes() = raise(NotOverriden.new("You must define the default scopes for filtering"))

      # Page number for pagination to start
      # @return [Integer] the page number for pagination to start
      def page_number
        page ||= params.dig(:page, :number) || 1
        page = 1 if page.to_i == 0
        page
      end

      # Number of items per page
      # @return [Integer] the number of items per page
      def page_size
        per_page ||= params.dig(:page, :size) || 25
        per_page
      end
    end
  end
end