repo_dep_injection.rb

class Repository
  extend Forwardable

  attr_reader :question, :task_list, :task

  def_delegator :question, :id, :question_id
  def_delegator :question, :alias, :question_alias
  def_delegator :question, :summary, :question_summary

  def_delegator :task, :id, :task_id
  def_delegator :task, :type, :task_type
  def_delegator :task, :title, :task_title
  def_delegator :task, :description, :task_description

  def_delegator :project, :id, :project_id
  def_delegator :project, :title, :project_title

  def initialize(question:, task:, task_list:)
    @question = question
    @task = task
    @task_list = task_list
  end

  def project
    @project ||= task_list.project
  end
end

class RepositoryBuilder
  attr_reader :repository

  def initialize(question_id)
    # This may look a bit weird, but I need to .find each of the models
    # the Repository needs in order to get their parents
    #
    # The dependency graph is as follows:
    # Project < Task List < Task < Question
    question = Question.find_with_tags(question_id)
    task = Task.find(question.task.id)
    task_list = Crowdlab::Model::TaskList.find(task.task_list.id)
    repository_options = {
      question: question, task: task, task_list: task_list
    }
    @repository = Repository.new(repository_options)
  end
end

class QuestionTagsController < ApplicationController
  # ...

  def set_breadcrumbs
    @repo = RepositoryBuilder.new(params[:question_id]).repository
    home_breadcrumb
    add_breadcrumb(label: @repo.project_title,
                   link: project_path(@repo.project_id),
                   icon: "icon_project")
  end
end