Create a Database Migration

Name: New Migration
Rating: 72
Author: gregszero

Adds a new table or modifies the database schema.

Steps

1. Create Migration File

File: workspace/migrations/YYYYMMDDNNNNNN_description.rb

Use the next number in sequence. Check existing migrations:

bash

ls workspace/migrations/

Existing migrations use the format 20260216NNNNNN. For new ones, use today's date.

Create Table

ruby

class CreateThings < ActiveRecord::Migration[8.0]
  def change
    create_table :things do |t|
      t.string :name, null: false
      t.text :description
      t.string :status, default: 'active'
      t.integer :count, default: 0
      t.references :conversation, foreign_key: true
      t.json :metadata, default: {}
      t.timestamps
    end

    add_index :things, :name, unique: true
    add_index :things, :status
  end
end

Modify Table

ruby

class AddFieldToThings < ActiveRecord::Migration[8.0]
  def change
    add_column :things, :new_field, :string
    add_index :things, :new_field
  end
end

2. Create Model

File: fang/models/thing.rb

ruby

# frozen_string_literal: true

module Fang
  class Thing < ActiveRecord::Base
    self.table_name = 'things'

    # Include concerns as needed
    # include HasStatus  # adds status scopes (e.g., statuses :active, :archived)

    validates :name, presence: true

    scope :recent, -> { order(created_at: :desc) }
  end
end

3. Run Migration

bash

./openfang.rb db:migrate

Conventions

•Migration class name matches the file description in PascalCase
•Table names are plural, model class names are singular
•Always use self.table_name = 'table_name' in models
•All models live under the Fang module
•Models are auto-loaded from fang/models/ by bootstrap.rb
•Use HasStatus concern for models with status fields — gives you scopes like .published, .draft
•Prefer json type for flexible metadata columns