Strategies for cleaning databases in Ruby. Can be used to ensure a clean state for testing.
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Latest commit 6432b5c Jul 8, 2010 @ayanko - Added option new :method to truncation strategy. Possible values :t…
…runcate or :purge

- Update README


Database Cleaner

Database Cleaner is a set of strategies for cleaning your database in Ruby.
The original use case was to ensure a clean state during tests. Each strategy
is a small amount of code but is code that is usually needed in any ruby app
that is testing with a database.

ActiveRecord, DataMapper, MongoMapper, Mongoid, and CouchPotato are supported.

How to use

  require 'database_cleaner'
  DatabaseCleaner.strategy = :truncation

  # then, whenever you need to clean the DB

With the :truncation strategy you can also pass in options, for example:

DatabaseCleaner.strategy = :truncation, {:only => %w[widgets dogs some_other_table]}

  DatabaseCleaner.strategy = :truncation, {:except => %w[widgets]}
  DatabaseCleaner.strategy = :truncation, {:except => %w[widgets], :method => :purge}
  DatabaseCleaner.strategy = :truncation, {:method => :truncate}

(I should point out the truncation strategy will never truncate your schema_migrations table.)

Truncation strategy options:

  • only – array of tables to be truncated
  • except – array of tables that will be excluded from truncation
  • method:
  • :truncate – will use TRUNCATE TABLE sql
  • :purge – will use DELETE FROM sql

With :purge option truncation are faster then with :truncate.
(especially if you have hundred or more tables)

Some strategies require that you call DatabaseCleaner.start before calling clean
(for example the :transaction one needs to know to open up a transaction). So
you would have:

  require 'database_cleaner'
  DatabaseCleaner.strategy = :transaction

  DatabaseCleaner.start # usually this is called in setup of a test
  DatabaseCleaner.clean # cleanup of the test

At times you may want to do a single clean with one strategy. For example, you may want
to start the process by truncating all the tables, but then use the faster transaction
strategy the remaining time. To accomplish this you can say:

  require 'database_cleaner'
  DatabaseCleaner.clean_with :truncation
  DatabaseCleaner.strategy = :transaction
  # then make the DatabaseCleaner.start and DatabaseCleaner.clean calls appropriately

Example usage with RSpec:

Spec::Runner.configure do |config|

  config.before(:suite) do
    DatabaseCleaner.strategy = :transaction

  config.before(:each) do

  config.after(:each) do


For use in Cucumber please see the section below.


One of my motivations for writing this library was to have an easy way to
turn on what Rails calls “transactional_fixtures” in my non-rails
ActiveRecord projects. For example, Cucumber ships with a Rails world that
will wrap each scenario in a transaction. This is great, but what if you are
using ActiveRecord in a non-rails project? You used to have to copy-and-paste
the needed code, but with DatabaseCleaner you can now say:

  require 'database_cleaner'
  require 'database_cleaner/cucumber'
  DatabaseCleaner.strategy = :transaction

Now lets say you are running your features and it requires that another process be
involved (i.e. Selenium running against your app’s server.) You can simply change
your strategy type:

  require 'database_cleaner'
  require 'database_cleaner/cucumber'
  DatabaseCleaner.strategy = :truncation

You can have the best of both worlds and use the best one for the job:

require ‘database_cleaner’
require ‘database_cleaner/cucumber’
DatabaseCleaner.strategy = (ENV[‘SELENIUM’] == ‘true’) ? :truncation : :transaction


Copyright © 2009 Ben Mabey. See LICENSE for details.