Is seeding data with fixtures dangerous in Ruby on Rails

Question

I have fixtures with initial data that needs to reside in my database (countries, regions, carriers, etc.). I have a task rake db:seed that will seed a database.

namespace :db do
  desc "Load seed fixtures (from db/fixtures) into the current environment's database." 
  task :seed => :environment do
    require 'active_record/fixtures'

    Dir.glob(RAILS_ROOT + '/db/fixtures/yamls/*.yml').each do |file|
      Fixtures.create_fixtures('db/fixtures/yamls', File.basename(file, '.*'))
    end
  end
end

I am a bit worried because this task wipes my database clean and loads the initial data. The fact that this is even possible to do more than once on production scares the crap out of me. Is this normal and do I just have to be cautious? Or do people usually protect a task like this in some way?

Answer 1

Seeding data with fixtures is an extremely bad idea.

Fixtures are not validated and since most Rails developers don't use database constraints this means you can easily get invalid or incomplete data inserted into your production database.

Fixtures also set strange primary key ids by default, which is not necessarily a problem but is annoying to work with.

There are a lot of solutions for this. My personal favorite is a rake task that runs a Ruby script that simply uses ActiveRecord to insert records. This is what Rails 3 will do with db:seed, but you can easily write this yourself.

I complement this with a method I add to ActiveRecord::Base called create_or_update. Using this I can run the seed script multiple times, updating old records instead of throwing an exception.

I wrote an article about these techniques a while back called Loading seed data.