Database Migrations

A migration is a set of changes we want to make to our database.

By defining migrations, we’re telling Rails how to change the database to add, change, or remove tables, columns or other attributes of our database. This helps keep track of changes we make in development (only on our computer) so they can be deployed to production (live, online!) safely.

In the editor, open the migration Rails created for us so we can see what the migration does. This is located in db/migrate/20250521010850_create_products:

class CreateProducts < ActiveRecord::Migration[8.0]
  def change
    create_table :products do |t|
      t.string :name

      t.timestamps
    end
  end
end

This migration is telling Rails to create a new database table named products.

The create_table block then defines which columns and types should be defined in this database table.

t.string :name tells Rails to create a column in the products table called name and set the type as string.

t.timestamps is a shortcut for defining two columns on your models: created_at:datetime and updated_at:datetime. You’ll see these columns on most Active Record models in Rails and they are automatically set by Active Record when creating or updating records.