Rails - Sep 2006 - Helpers and Migrations

Hello all,
I''m once again struggling with a migration problem. I posted about this
last night, but I realize that this really is a separate problem and probably
needs its own thread.

I''m attempting to write a migration where I need foreign key
constraints. I used the code located at the following location to create a
migration_helpers.rb file:

http://seb.box.re/articles/2006/07/29/foreign-key-and-rails-migration#comments

Then, I added the migration_helpers.rb file under my lib directory in my site. I
changed the foreign key calls to look like:
    foreign_key(:users_roles, :userid, :users)

However, I get the following complaint when I run rake:
rake aborted!
undefined method `foreign_key'' for
#<ActiveRecord::ConnectionAdapters::MysqlAdapter:0xb75a5d0c>

The declaration in my migration file looks like this:
require "migration_helpers" 
class MyWeb < ActiveRecord::Migration
  extend MigrationHelpers
    def self.up

I''ve also tried it as follows:
require "migration_helpers" 
 class MyWeb < ActiveRecord::Migration
   include MigrationHelpers
     def self.up

This is the first time I''ve tried to use a module, so I don''t
know what''s going on. I know that when I moved the helper file, I got a
complaint that rake couldn''t find it. This leads me to believe that the
helper was in the right location. Here are the contents of the helper file, by
the way.

module MigrationHelpers
  def foreign_key(from_table, from_column, to_table)
    execute %{alter table #{from_table}
              add constraint #{self.to_contraint_name( from_table, from_column
)}
              foreign key (#{from_column})
              references #{to_table}(id)}
  end
  
  def drop_foreign_key(from_table, from_column, to_table)
    execute "alter table #{from_table} DROP FOREIGN KEY
#{self.to_contraint_name(from_table, from_column)}"
  end
  
  def to_contraint_name(from_table, from_column)
    return "fk_#{from_table}_#{from_column}" 
  end
end

Does anyone have any idea why this is failing?

 		
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