Why "require" cannot find a file in Ruby on Rails 3 application?

I would to populate the database (MySQL) with some dummy entries as the application starts.

I created:

class DatabaseInitializer
  def populate_database
    ...
  end
end

in lib/database_initializer.rb.

I understand that all files in the lib directory should have been loaded automatically.

Question 1: Is there any command to see a list of all files that have been loaded ?

Then, in controllers/main_controller.rb I have:

require 'lib/database_initializer.rb'
class MainController < ApplicationController
  def initialize
    Database开发者_运维技巧Initializer.new.populate_database
  end
  def index
    ...
  end  
end

But, I got the following error:

LoadError in MainController#index
no such file to load -- lib/database_initializer.rb

Question 2: Why it cannot find database_initializer.rb ?

Question 3: Is this "Rails enough" way to pre-populate a database ? Would you do this otherwise (put database_initializer.rb in other place, call DatabaseInitializer.new.populate_database from other place, e.t.c.) ?

Question 1

$LOADED_FEATURES

Question 2

# the 'lib' directory is already added to the load
# path in the Rails initialization process, so simply:
require 'database_initializer`

Question 3

# db/seeds.rb
c = Company.create! :name => 'ABC Inc.'
p = Person.create! :name => 'Jeremy', :company => c

$ rake db:seed

When requiring files from ruby you generally drop the file extension. Try require database_initializer. lib/ was briefly removed from the load path in rails-3 but I think it's back now. If not, see config.autoload_paths in config/application.rb.

However, I think this is probably a bad idea in general. If you need to ensure that you always have a consistent and immutable set of data available to your app, why not just define it in ruby in a model?

Also, there is already a mechanism for adding seed data in rails. See db/seeds.rb and the command rake db:seed

For any file in lib, you should only have to use: require 'database_initializer'.