Clear all postgres database with Rails

truncate_db.rake

desc 'delete all data from db except migrations'
task :truncate_db => :environment do
  conn = ActiveRecord::Base.connection
  postgres = "SELECT tablename FROM pg_catalog.pg_tables WHERE schemaname='public'"
  tables = conn.execute(postgres).map { |r| r['tablename'] }
  tables.delete "schema_migrations"
  tables.each { |t| conn.execute("TRUNCATE \"#{t}\" CASCADE") }
end