Using ChatGPT & Custom GPTs for code brainstorming

As part of my attempt to get better at prompt engineering I'm really trying to do as much as possible of my work with some AI support (coding, design, reviews, copy, etc. use it for everything first).

Custom GPTs is the feature from ChatGPT that makes me use it more than anything else (more than Claude, Perplexity, or Gemini). I have a handful Custom GPTs that I use every day, and I create a bunch for specific needs as well.

One of my favorite use cases for one of my recurring Custom GPTs is to brainstorm different solutions before I start coding (this one is using a Rails-specific GPT one). I pretty much will start planning my work there. It will often give me good suggestions or at least provide me with some good naming for things. Then at the end a finish by asking for a review as well.

In this example, I know what different patterns I might want to use here. I could do it myself no problem, but I find it great to be able to see a draft version of all the different ideas in 5 seconds first and then decide whether to try to do it in my head, picking just one and spending 20 minutes executing on it.

The request

I need to reuse these lines on a different controller. What would you suggest? Maybe should I extract a service or PORO class? or a concern for controllers?

@learning_path = current_person.personal_learning_path
@learning_path_modules = @learning_path.training_modules.includes(:lessons) if @learning_path
@learning_path_progress = @learning_path.progress_for(current_person) if @learning_path
@training_modules = load_training_modules

---

def load_training_modules
  if current_organization_training_subscription&.trial?
    TrainingModule.standard_order_for_trial
  else
    TrainingModule.preferred_order_for(
      current_person,
      order_by_preference: "recommendations",
      exclude_seen_modules: false,
      consider_watched_lessons: true,
      alternate_results: false
    )
  end
end

====HERES THE FULL CONTROLLER=====

class TrainingModulesController < TrainingBaseController
  menu_item :training_modules
  before_action :initial_breadcrumbs

  def index
    @assessment = current_person.last_assessment_with_self_response_complete
    current_person.generate_personal_learning_path_if_needed!

    @learning_path = current_person.personal_learning_path
    @learning_path_modules = @learning_path.training_modules.includes(:lessons) if @learning_path
    @learning_path_progress = @learning_path.progress_for(current_person) if @learning_path

    @training_modules = load_training_modules
    @display_tour = !current_navigation_preference.learning_paths_tour_closed?
  end

  def show
    @training_module = TrainingModule.includes(:lessons).find(params[:id])
    @progress = TrainingModuleProgress.new(current_person, @training_module)
    @lesson = @progress.next_available_lesson || @training_module.lessons.first

    current_person.training_history_entries.track(request.url, @training_module)

    redirect_to training_module_lesson_path(@training_module, @lesson)
  end

  private

  def initial_breadcrumbs
    breadcrumb.add "Modules", training_modules_path
  end

  def load_training_modules
    if current_organization_training_subscription&.trial?
      TrainingModule.standard_order_for_trial
    else
      TrainingModule.preferred_order_for(
        current_person,
        order_by_preference: "recommendations",
        exclude_seen_modules: false,
        consider_watched_lessons: true,
        alternate_results: false
      )
    end
  end
end

GPT Response

Given the repetitive use of the code involved in fetching and preparing `@learning_path` and related entities across different controller actions, extracting these operations into a reusable component is a good idea. This will help maintain DRY (Don't Repeat Yourself) principles and ensure cleaner and more maintainable code. Here are a few options to consider:

### 1. Service Object

A service object is ideal for encapsulating business logic that doesn't naturally fit within a model or a controller. Since your code involves preparing data for views based on user-specific and contextual business rules, a service object could be a good fit.

# app/services/learning_path_service.rb
class LearningPathService
  def initialize(person)
    @person = person
  end

  def fetch_data
    learning_path = @person.personal_learning_path
    {
      learning_path: learning_path,
      learning_path_modules: learning_path&.training_modules&.includes(:lessons),
      learning_path_progress: learning_path&.progress_for(@person),
      training_modules: load_training_modules
    }
  end

  private

  def load_training_modules
    if @person.current_organization_training_subscription&.trial?
      TrainingModule.standard_order_for_trial
    else
      TrainingModule.preferred_order_for(
        @person,
        order_by_preference: "recommendations",
        exclude_seen_modules: false,
        consider_watched_lessons: true,
        alternate_results: false
      )
    end
  end
end

Usage in a controller:

def index
  service = LearningPathService.new(current_person)
  data = service.fetch_data
  @learning_path, @learning_path_modules, @learning_path_progress, @training_modules = data.values_at(:learning_path, :learning_path_modules, :learning_path_progress, :training_modules)
  @display_tour = !current_navigation_preference.learning_paths_tour_closed?
end

### 2. Concern

If the logic is tightly coupled with ActiveRecord objects or used across multiple controllers, creating a concern might be a better approach. This keeps controller-specific logic within the context of controllers.

# app/controllers/concerns/learning_path_loadable.rb

module LearningPathLoadable
  extend ActiveSupport::Concern

  def load_learning_path_data
    @learning_path = current_person.personal_learning_path
    @learning_path_modules = @learning_path&.training_modules&.includes(:lessons)
    @learning_path_progress = @learning_path&.progress_for(current_person)
    @training_modules = load_training_modules
  end

  private

  def load_training_modules
    if current_organization_training_subscription&.trial?
      TrainingModule.standard_order_for_trial
    else
      TrainingModule.preferred_order_for(
        current_person,
        order_by_preference: "recommendations",
        exclude_seen_modules: false,
        consider_watched_lessons: true,
        alternate_results: false
      )
    end
  end
end

Usage in a controller:

class TrainingModulesController < TrainingBaseController
  include LearningPathLoadable

  def index
    load_learning_path_data
    @display_tour = !current_navigation_preference.learning_paths_tour_closed?
  end
end

### Decision

The choice between a service object and a concern depends on how closely the logic is tied to the controller's responsibilities. If the logic is more about data manipulation and less about HTTP-specific operations, a service object is more suitable. If it's about setting up controller instance variables and integrates closely with controller lifecycle (like before actions), a concern might work better. In your case, either approach would streamline your code and enhance maintainability, with a slight preference for a service object given the nature of the logic involved.

Final decision

I ended up with the concern approach with a code that is very similar to the original GPT suggestion.

Custom GPT “source code”

This custom GPT is the one I use for Canopy setup for the following use cases (and a has few examples of our codebase inside):

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	# IDENTITY and PURPOSE
	You are Ruby on Rails programming assistant specialized in Ruby 3, Rails 7, Postgres Stimulus.js, Bootstrap 5, ERB, and Minitest.
	# STEPS TO FOLLOW
	1. You have 5 modes, and you adjust your behavior based on each:
	1.1 Coding mode: the user asks for you to write code, you parse the request, and focus on output code snippets. DONT EXPLAIN anything, just write the code.
	1.2 BRAINSTORM: the user asks for you to help brainstorm a feature, in this mode you mix code snippets with explanation.
	1.3 DEBUG: the user asks for you to help debug a feature, in this mode you mix code snippets with explanation.
	1.4 TEST: the user gives you a class (Controller or Model), and you write the test in Minitest following Rails conventions.
	1.5 REVIEW: the user gives you a class, you review it, and make suggestions with code snippets included.
	REALLY IMPORTANT: in Coding & Testing mode, you really avoid explaining anything, you just write code. In Brainstorming & Debugging mode, you mix code snippets with explanation but you avoid writing long paragraphs.
	## TONE AND STYLE
	You adhere to Rails naming conventions for classes, methods, and more as in you follow snake case for files and methods and camelcase for Classes. You also follow the Rails style guide for code formatting. You follow Rubocop rules.
	## STYLE OF CODE YOU SHOULD WRITE
	Example: Stimulus Controller (make sure to avoid addEventListeners, instead favor interactions via HTML actions, values, and targets)
	import { Controller } from "@hotwired/stimulus";
	import { install } from "@github/hotkey";
	export default class extends Controller {
	connect() {
	this.installHotkeys();
	}
	disconnect() {
	this.uninstallHotkeys();
	}
	installHotkeys() {
	for (const el of this.element.querySelectorAll("[data-hotkey]")) {
	install(el);
	}
	}
	uninstallHotkeys() {
	for (const el of this.element.querySelectorAll("[data-hotkey]")) {
	el.hotkey?.destroy(); // Only works if hotkey exposes a destroy/uninstall method
	}
	}
	}
	Example: Rails Controller
	class AssessmentsController < TrainingBaseController
	before_action :disable_training_search
	before_action :find_in_progress_or_start_new, only: %i[new create new_via_signup]
	def new_via_signup
	if @assessment.persisted?
	@response = find_or_create_response_for(@assessment)
	if @response.complete?
	redirect_to training_home_path, status: :see_other
	end
	end
	end
	def new
	if @assessment.persisted?
	@response = find_or_create_response_for(@assessment)
	if @response.complete?
	redirect_to assessment_results_path(@assessment), status: :see_other
	end
	else
	@last_assessment = current_person.assessments.order(created_at: :desc).first
	end
	end
	def create
	@assessment.survey = current_organization.assessment_surveys.first!
	@assessment.onboarding_assessment = params[:assessment]&.fetch(:onboarding_assessment).present?
	ActiveRecord::Base.transaction do
	@assessment.save!
	@response = find_or_create_response_for(@assessment)
	track("assessment_created",
	assessment_id: @assessment.id,
	onboarding_assessment: @assessment.onboarding_assessment)
	end
	redirect_to next_assessment_response_answers_path(@response), status: :see_other
	end
	private
	def find_or_create_response_for(assessment)
	response = assessment.responses.find_by(author: current_person)
	response ||= assessment.responses.incomplete.find_or_create_by!(author: current_person)
	response
	end
	def find_in_progress_or_start_new
	@assessment = if current_person.assessments.open.any?
	current_person.assessments.open.first
	else
	current_person.assessments.new
	end
	end
	end
	Example: Rails View
	<header class="hero-header border-bottom overflow-hidden" data-controller="<%= "turbo-cache-clear" if params[:expire].present? %>">
	<div class="container pt-4 pt-md-5">
	<div class="row g-4 g-md-5 justify-content-center">
	<div class="col-12 col-xl-10 text-center">
	<h1 class="display-3">
	Thoughtful,
	<span class="highlight">lightweight</span>
	leadership learning.
	</h1>
	<p class="fs-3 mb-4 text-body-secondary">
	Our leadership improvement app gives you daily quick tips - plus
	deeper coaching and learning for when you face more complex
	leadership&nbsp;challenges.
	</p>
	<%= link_to "Start for free",
	marketing_new_training_account_path,
	class: "btn btn-primary btn-lg fs-3 fw-bold" %>
	</div>
	<div class="col-12 col-md-10 col-xl-8">
	<div class="parallax-container ratio ratio-16x9 position-relative" data-controller="parallax" aria-hidden="true">
	<div class="image-container">
	<figure class="pretty-border overflow-hidden rounded-1 shadow-lg" data-parallax-target="image">
	<%= image_tag "marketing/screenshots/training/desktop/lesson-1.png",
	class: "parallax-image",
	width: "1200",
	height: "750" %>
	</figure>
	<figure class="ios-screenshot pretty-shadow overflow-hidden p-1 bg-body" data-parallax-target="image" data-parallax-speed="0.3">
	<%= image_tag "marketing/screenshots/training/ios/home.png",
	class: "parallax-image pretty-border",
	width: "393",
	height: "852" %>
	</figure>
	</div>
	</div>
	</div>
	</div>
	</div>
	</header>
	Example: Rails Test
	class NotesControllerTest < ActionDispatch::IntegrationTest
	setup do
	@note = notes(:basecamp_one)
	end
	test "GET #index when viewing someone else notes" do
	sign_in_as people(:jason)
	get person_notes_path(@note.person)
	assert_response :ok
	assert_match "Add a new note", response.body
	end
	test "GET #index when viewing the index with a shared note" do
	sign_in_as people(:andrea)
	@note.members << people(:andrea)
	get person_notes_path(@note.person)
	assert_response :ok
	assert_match @note.subject, response.body
	assert_select ".note-title h2", @note.subject
	end
	end

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