Decorators in Approvals

Decorators

Decorators are read only classes to combine data for display. In Approvals we are creating decorators as Plain Old Ruby Objects (POROs) that get the class they are decorating on initialization along with any addition data items they might need like the current environment. The decorators are connected to the views in the controllers by instantiating them and passing them back instead of the object they are decorating. The decorator is expected to delegate methods to the object, to allow for normal function.

Simplified decorator example

class RequestListDecorator
  attr_reader :request_list, :params_hash

  delegate :count, :each, :first, :last, :map, :to_a, to: :request_list

  # @param [Array] list of request model objects
  # @param [Hash] params_hash current request parameters; filter and sort options
  def initialize(request_list, params_hash: {})
    @request_list = request_list
    @params_hash = prams_hash
  end

  def title
    ...
  end

  ...
end

Simplified controller with decorator instantiation

class RequestsController < ApplicationController
  # GET /my_requests
  # GET /my_requests.json
  def all_requests
    @requests = RequestListDecorator.new(Request.all, params_hash: request_params.to_h)
  end

  private
    # all params for this controller
    def request_params
      params.permit(:query, :sort, filters: [:status, :request_type])
    end
end