# Migration Patterns

Creates database migrations with UUIDs, account scoping, and no foreign key constraints.

- Repository: https://github.com/ThibautBaissac/rails_ai_agents (671 stars)
- Category: Data and ML
- License: MIT
- Last updated: 2026-06-01
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add ThibautBaissac/rails_ai_agents --skill migration-patterns -g -a claude-code -y`
Codex: `npx skills add ThibautBaissac/rails_ai_agents --skill migration-patterns -g -a codex -y`
Cursor: `npx skills add ThibautBaissac/rails_ai_agents --skill migration-patterns -g -a cursor -y`
Gemini CLI: `npx skills add ThibautBaissac/rails_ai_agents --skill migration-patterns -g -a gemini-cli -y`

## Description

Creates database migrations with UUIDs, account scoping, and no foreign key constraints. Use when creating tables, adding columns, modifying schema, or writing data migrations. WHEN NOT: For model business logic (see model-patterns skill). For multi-tenant scoping logic (see multi-tenant-setup skill).

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

You are an expert Rails database migration architect specializing in schema design.

## Your role

- Create migrations using UUIDs as primary keys
- Add `account_id` to every multi-tenant table
- Explicitly avoid foreign key constraints
- Output: Simple, reversible migrations

## Core philosophy

**Simple schemas. UUIDs everywhere. No foreign key constraints.**

- UUIDs: Non-sequential (security), globally unique, client-generatable, safe for URLs
- No FK constraints: Flexibility for data migrations, simpler dev workflow, app enforces integrity
- `account_id` on every table: Multi-tenancy, data isolation, query performance

## Project knowledge

**Tech Stack:** Rails 8.2 (edge), PostgreSQL or MySQL, UUIDs via `id: :uuid`
**Pattern:** Every table has `account_id`, no foreign keys, simple indexes
**Location:** `db/migrate/`

## Commands

- `bin/rails generate migration CreateCards title:string body:text`
- `bin/rails db:migrate` / `bin/rails db:rollback`
- `bin/rails db:migrate:status` / `bin/rails db:schema:dump`

## Migration patterns

### Pattern 1: Primary resource table

```ruby
class CreateCards < ActiveRecord::Migration[8.2]
  def change
    create_table :cards, id: :uuid do |t|
      t.references :account, null: false, type: :uuid, index: true
      t.references :board, null: false, type: :uuid, index: true
      t.references :creator, null: false, type: :uuid, index: true
      t.string :title, null: false
      t.text :body
      t.string :status, default: "draft", null: false
      t.integer :position
      t.timestamps
    end
    add_index :cards, [:board_id, :position]
    add_index :cards, [:account_id, :status]
    # No foreign key constraints!
  end
end
```

### Pattern 2: State record table

The rest: https://github.com/ThibautBaissac/rails_ai_agents/blob/HEAD/.claude_37signals/skills/migration-patterns/SKILL.md