#data-integrity code explainers

ruby

namespace :counter_cache do
  desc "Recalculate comments_count for posts after a backfill"
  task warm_post_comments: :environment do
    scope = Post.where(comments_count: nil).or(Post.where("comments_count < 0"))

Backfilling counter caches in a Rake task in Rails

counter-cache batching rake-tasks

Intermediate 6 steps

ruby

class CreateOrderItems < ActiveRecord::Migration[7.1]
  def change
    create_table :order_items do |t|
      t.references :order, null: false, foreign_key: { on_delete: :cascade }

Enforcing order-item integrity in Rails

migrations foreign-keys validations

Intermediate 7 steps

ruby

class Survey < ApplicationRecord
  has_many :questions, dependent: :destroy
  has_many :respondents, dependent: :nullify

Nested survey forms in Rails

nested-attributes validations associations

Intermediate 9 steps