Database Migrations (6.2)

Recently found out how to migrate/alter applications database.

Let's take a look at the contents of our new migration file:

class CreateArticles < ActiveRecord::Migration[7.0]
  def change
    create_table :articles do |t|
      t.string :title
      t.text :body

      t.timestamps
    end
  end
end

The call to create_table specifies how the articles table should be constructed. By default, the create_table method adds an id column as an auto-incrementing primary key. So the first record in the table will have an id of 1, the next record will have an id of 2, and so on.

Inside the block for create_table, two columns are defined: title and body. These were added by the generator because we included them in our generate command (bin/rails generate model Article title:string body:text).

On the last line of the block is a call to t.timestamps. This method defines two additional columns named created_at and updated_at. As we will see, Rails will manage these for us, setting the values when we create or update a model object.