Step by Step Guide to using Cursor AI to Add a Blog (with Markdown support) to a Ruby on Rails App

by p4xio

In this multi-step AI prompt project, I will go over how to add a Blog (with Markdown formatting support) to your existing Ruby on Rails webapp. It 's not the most complex process, but there may be some gotchas that come up when adding this to an existing RoR app.

This will just be a basic Blog without categories, etc. Just the ability to create posts, etc.

For this workflow, I will be using Cursor AI, but the process should work similarly for other AI-powered code editors and tools.

https://www.cursor.com/

Follow me on X for more AI prompt workflows:

https://x.com/p4xiobuilds

Step #1: Project Overview

This prompt is just to give you an overall idea of what we are trying to achieve. We want to add a Blog (or Weblog) to an existing Ruby on Rails application. We'll presume we do not yet have a Post model or anything like it, so we will be doing that from scratch.

Let's use the existing default Rails application layout that the rest of the app uses.

An outline for the Blog feature development plan:

* Generating the Post model and posts table
* Creating a new Posts controller, namespaced under a Blog module + adding actions for all of the core/common Rails CRUD methods: index, new, edit, create, update and destroy
* Adding views on the Posts controller for index, new, edit and show

That's it for now. Do not generate any code yet, we will begin shortly.

Expected Output: Text

This is just to give the LLM an overview of what we are trying to achieve.

Notes/Instructions

Step #2: Generate the Post model via the Rails' CLI

bin/rails generate model post title:string body:text user:references is_published:boolean

Expected Output: Text

We are going to assume you already have a User model that you'd like to integrate with the Blog, so that Posts belong to users.

Notes/Instructions

Step #3: Run the Migrations

bin/rails db:migrate

Expected Output: Text

It is necessary to run the migrations after any schema change.

Notes/Instructions

Step #4: Update Post model with Associations + Create a Posts Controller nested under a New Blog Module

Update the Post model with all relevant associations and validations.

Then let's add a new Posts controller, namespaced under a new Blog module.

So the Posts controller would go reside in: app/controllers/blog/posts_controller.rb

Do NOT create a migration for adding a new Post model--we already did that.

Expected Output: Text

Step #5: Require Authentication for the non-public Post Controller Actions

Let's lock down our non-public actions so that only authenticated users with the right permissions can access them. We're going to assume you're using the "devise" gem for users/auth.

At the top of your PostsController, add:

  before_action :authenticate_user!, only: [:new, :edit, :create, :update, :destroy]
  before_action :require_admin_user, only: [:new, :edit, :create, :update, :destroy]

Down at the bottom of the controller, create a "protected" area for methods above "private", add something like:

def require_admin_user
  unless current_user.is_admin
    redirect_to :root_path, "Ooops! You did a aughty naughty! You can't do that."
  end
end

Or something along those lines--it will depend on how your app handles roles/etc.

Expected Output: Text

After adding this, you may want to do a "bin/rails routes" just to see all the routes that have been created.

Notes/Instructions

Step #6: Adding views for the Posts controller for the index, new, edit and show Actions

Generate views for our new Posts controller for the following views: index, new, edit and show

Use Tailwind CSS. Style the page and components in a similar fashion to how other pages and elements are styled in the rest of the app.

Expected Output: Multiple files

You'll want to modify the prompt to use the appropriate CSS framework if you are not using Tailwind, or none.

Notes/Instructions

Step #7: Use a Single _form Partial for the New and Show Views

Let's refactor the views to use a single _form.html.erb partial that is shared between the new and edit actions.

Expected Output: Multiple files

I had to tell Cursor to do this. I think it's a cleaner approach overall and cuts down on code updating to modify the form views, etc.

If you are using a dark theme, it may have generated labels & text that are hard to read. I had to give it this prompt to update the views to work better with my dark theme:

My theme is a dark mode theme. Please update the new blog posts controller views to work better with a dark mode theme. text colors and labels should be white, etc

Notes/Instructions

Step #8: Make Sure the User has a Posts Association

When trying to create a new Post now, I'm getting the error:

undefined method `posts' for an instance of User

I think we need to add a :posts association on the User model.

Expected Output: Text

After this, try visiting "/blog/posts" as an admin and add several posts. You will still likely need to tweak the CSS of course to get it to look nice.

Notes/Instructions

Step #9: Update the Posts Index View to be more Blog-like

Let's update this posts index view to look more like a traditional blog. instead of multiple cards for each post, let's have each post take up the full width of the page. Also, the post title should link to the show page of the post.

Expected Output: Text

Step #10: Ew, these Post URLs Suck! Let's Make em look nice!

rails g migration add_slug_to_posts slug:string
rails db:migrate

Expected Output: Text

Cursor does not seem to play nice with rails migrations (generating them for us), so let's add one by hand using the CLI.

Notes/Instructions

Step #11: Some Minor Code Updates to get Slugs Working

If you try to load your blog after the last step, you'll get an error if you have any posts in your db. I had to run this via the rails console to set the slugs for my existing posts:

  Post.all.map { |p| p.send(:set_slug); p.save }

Cursor did not nail the slug feature for me, I had to set this as the set_post method in the posts controller:

    def set_post
      @post = Post.find_by!(slug: params[:slug])
    end

Because this is what it set for me in routes.rb:

  namespace :blog do
    resources :posts, param: :slug
  end

Expected Output: Text

Step #12: Prepare for Enabling Markdown Support for Blog Post Bodies

Add the following to your Gemfile if it's not already there:

gem "redcarpet"

Then make sure it's installed with:

bundle install

Expected Output: Text

Step #13: Enable Markdown Support for Rendering Post Content

Let's add Markdown formatting support for blog post bodies. Create a helper method in ApplicationHelper that will take markdown-formatted text and convert it into HTML using the redcarpet gem. On the Show Post page, use the new markdown formatting method to output generated HTML for the post based on its markdown content.

Expected Output: Multiple files

This should generate the necessary code to complete the addition of Markdown formatting support for posts. I had to tweak the application.tailwind.css file it generated and include it in my main application.css file, and even then it did not look great. But it's a starting point.

This concludes my How to Add a Blog to a RoR App AI Prompt tutorial. There's plenty left to do from here, of course--such as adding categories or tags, etc. If you want to extend this AI Prompt project, sign up for an account on Prompt Maven and create a new AI Prompt Project to explain how you'd do so. Thanks!

Notes/Instructions

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Step by Step Guide to using Cursor AI to Add a Blog (with Markdown support) to a Ruby on Rails App

Step #1: Project Overview

Step #2: Generate the Post model via the Rails' CLI

Step #3: Run the Migrations

Step #4: Update Post model with Associations + Create a Posts Controller nested under a New Blog Module

Step #5: Require Authentication for the non-public Post Controller Actions

Step #6: Adding views for the Posts controller for the index, new, edit and show Actions

Step #7: Use a Single _form Partial for the New and Show Views

Step #8: Make Sure the User has a Posts Association

Step #9: Update the Posts Index View to be more Blog-like

Step #10: Ew, these Post URLs Suck! Let's Make em look nice!

Step #11: Some Minor Code Updates to get Slugs Working

Step #12: Prepare for Enabling Markdown Support for Blog Post Bodies

Step #13: Enable Markdown Support for Rendering Post Content

Maximize your AI productivity. Start using Prompt Maven today. today.

Company

Resources

Legal

Maximize your AI productivity.
Start using Prompt Maven today. today.