JRuby on Rails with Nine Lives: Running a JRuby on Rails Application on Tomcat

Creating Your Migration

You will use Rails Migrations to manage the creation and deletion of the database table that you are going to use to manage your Guitars from your app. Your table is going to conveniently be named guitars. Run the following from the railswartest direcrory:

jruby script/generate migration add_a_new_table

This will create the db/migrate/001_add_guitar_table.rb file:

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Figure 10: Creating our add_guitar_table migration

This file contains a Ruby class named AddGuitarTable that extends Rails' ActiveRecord::Migration class. Edit this file to contain the following:

class AddGuitarTable < ActiveRecord::Migration
   def self.up
      create_table :guitars do |table|
         table.column :make,  :string, :null => false
         table.column :model, :string, :null => false
         table.column :color, :string, :null => false
      end
   end

   def self.down
      drop_table :guitars
   end
end

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Figure 11: AddGuitarTable migration class

Now, run the migration:

jruby -S rake db:migrate

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Figure 12: Running your migration to create the guitars table

Running MySQL Query Browser confirms that the guitars table has been created by the migration:

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Figure 13: Empty guitars table in MySQL