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Migrate Away your Cruft

Last summer I developed my first Rails application under a very tight deadline. I cut a few(!) corners and one was not creating a link from my Person table to my Team table for the team coach.

So I’m trying to clean up after myself a bit. It turns out that I can get about 90% of the way there for just a few quick lines of code:

class AddFieldsToTeam < ActiveRecord::Migration
  def self.up
    add_column :teams, :coach_id, :integer
    add_column :teams, :asst_coach_id, :integer

    Team.reset_column_information

    @teams = Team.find(:all)
    @teams.each do |t|
      c = Person.find_by_full_name t.coach
      ac = Person.find_by_full_name t.asst_coach
      if !c.nil? || ac.nil?
        t.coach_id = c.id unless c.nil?
        t.asst_coach_id = ac.id unless ac.nil?
        t.save
      end
    end
  end

  def self.down
    remove_column :teams, :coach_id
    remove_column :teams, :asst_coach_id
  end
end

Here’s the findby_fullname:

  def self.find_by_full_name(fn)
    name = fn.split
    find(:first, :conditions => ["void = 0 and first_name = ? and last_name = ?", name.first, name.last])
  end

That’s just too easy.

This entry was posted on Thursday, January 19th, 2006 at 9:56 pm and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

3 Responses to “Migrate Away your Cruft”

  • 1
    Scott Matthewman
    January 20th, 2006 05:55

    Hey Tom,

    The docs for migrations recommend a call to Base#resetcolumninformation after adding columns if you then need to populate them. Like you, I’ve found it’s not always necessary, but I reckon it’s good to get into the habit, especially if future versions of Rails cache more information than currently.

    Just add ‘Team.resetcolumninformation’ after your add_column lines and you’re covered.

  • 2
    Scott Matthewman
    January 20th, 2006 06:06

    Ah – I see you’ve got some markup codes running in your comments; sorry.

    The method should, of course, be reset_column_information.

  • 3
    Tom
    January 21st, 2006 06:00

    Hi Scott,

    Thanks for the pointer – I’ve updated the migration. One of those things that’s good to do even when it works otherwise.

    Thanks!