Add Rows on Migrations

Question

I'd like to know which is the preferred way to add records to a database table in a Rails Migration. I've read on Ola Bini's book (Jruby on Rails) that he does something like this:

class CreateProductCategories < ActiveRecord::Migration

  #defines the AR class
  class ProductType < ActiveRecord::Base; end

  def self.up

    #CREATE THE TABLES...

    load_data
  end
  def self.load_data
    #Use AR object to create default data
    ProductType.create(:name => "type")
  end
end

This is nice and clean but for some reason, doesn't work on the lasts versions of rails...

The question is, how do you populate the database with default data (like users or something)?

Thanks!

Answer 1

The Rails API documentation for migrations shows a simpler way to achieve this.

http://api.rubyonrails.org/classes/ActiveRecord/Migration.html

class CreateProductCategories < ActiveRecord::Migration
  def self.up
    create_table "product_categories" do |t|
      t.string name
      # etc.
    end

    # Now populate the category list with default data

    ProductCategory.create :name => 'Books', ...
    ProductCategory.create :name => 'Games', ... # Etc.

    # The "down" method takes care of the data because it
    # drops the whole table.

  end

  def self.down
    drop_table "product_categories"
  end
end

Tested on Rails 2.3.0, but this should work for many earlier versions too.

Answer 2

You could use fixtures for that. It means having a yaml file somewhere with the data you want to insert.

Here is a changeset I committed for this in one of my app:

db/migrate/004_load_profiles.rb

require 'active_record/fixtures'

class LoadProfiles < ActiveRecord::Migration
  def self.up
    down()

    directory = File.join(File.dirname(__FILE__), "init_data")
    Fixtures.create_fixtures(directory, "profiles")
  end

  def self.down
    Profile.delete_all
  end
end

db/migrate/init_data/profiles.yaml

admin:
 name: Admin
  value: 1
normal:
 name: Normal user
  value: 2

Answer 3

You could also define in your seeds.rb file, for instance:

Grid.create :ref_code => 'one' , :name => 'Grade Única'

and after run:

rake db:seed