Comment by localhostdotdev

    rails g model Post published_at:datetime title content:text
    rails g model Comment post:references author published_at:datetime content:text
    rails g model Tag name
    rails g model PostTag post:references tag:references

    class Post < ApplicationRecord
      has_many :comments
      has_many :post_tags
      has_many :tags, through: :post_tags
    end

    class Tag < ApplicationRecord
      has_many :post_tags
      has_many :posts, through: :post_tags
    end

from there it's just regular rails:

    Tag.find_by(name: "something").posts
    Post.joins(:tags).where(tags: { name: "something" })
    Tag.create(name: "something")
    Post.create(...)
    Tag.first.posts << Post.all.sample(2)

made a little repo if people want to play with it: https://github.com/localhostdotdev/bug/tree/orm-or-not-orm