As found at
http://media.pragprog.com/titles/fr_rr/code/CreateFixturesFromLiveData/lib/tasks/extract_fixtures.rake
desc 'Create YAML test fixtures from data in an existing database.
Defaults to development database. Set RAILS_ENV to override.'
task :extract_fixtures => :environment do
sql = "SELECT * FROM %s"
skip_tables = ["schema_info"]
ActiveRecord::Base.establish_connection
(ActiveRecord::Base.connection.tables - skip_tables).each do |table_name|
i = "000"
File.open("#{RAILS_ROOT}/test/fixtures/#{table_name}.yml", 'w') do |file|
data = ActiveRecord::Base.connection.select_all(sql % table_name)
file.write data.inject({}) { |hash, record|
hash["#{table_name}_#{i.succ!}"] = record
hash
}.to_yaml
end
end
end