Rack::Transaction

Rack::Transaction is a rack middleware that automatically wraps any incoming requests with potential side effects (i.e. POST, PUT, or DELETE).

Add this line to your Gemfile:

gem 'rack-transaction', :require => 'rack/transaction'

or

gem install rack-transaction

Add the following:

config = Rack::Transaction::Configuration.new do
  provided_by Sequel.connect('sqlite:///')  #required
  rollback_with Sequel::Rollback            #required (it also accepts the string version of the constant)
end

use Rack::Transaction, config

or, with the shorthand form:

use Rack::Transaction do
  provided_by Sequel.connect('sqlite:///')  #required
  rollback_with Sequel::Rollback            #required (it also accepts the string version of the constant)
end

Do note that rollback_with will use the type specified to raise an error, which in turn, causes the transaction to rollback. Depending on the provider, passed into provided_by, providing the transaction, you may want to specify an error type provided by the library being used to allow for more graceful error handling. For example, Sequel has Sequel::Rollback and ActiveRecord has ActiveRecord::Rollback.

It also supports an optional callback to validate that an action was successful, even if it wasn't recognized as a client or server error. For example, Sinatra sets sinatra.error on the env in the event of an error, so we'll probably want to rollback. We can specify the validation callback with ensure_success_with. The callback will have the Rack::Response and env passed to it as arguments.

use Rack::Transaction do
  provided_by Sequel.connect('sqlite:///')
  rollback_with Sequel::Rollback
  ensure_success_with { |response, env| env['sinatra.error'] }

By default, Rack::Transaction will wrap all requests except for request of methods GET, HEAD, & OPTION. It also provides away to include or exclude certain requests from participating in the transaction. This is done by passing in a block to include or exclude to the configuration. The block can expect a Rack::Request instance to be used to determine whether or not to include or exclude said request. For example, you may want to wrap a GET request in a transaction, because the action it routes to is handling the final leg of OAauth authorization and saving the refresh token as well as other business logic.

use Rack::Transaction do
  // other config stuff

  include { |request| request.path =~ %r{/oauth/callback$}i }
  exclude { |request| request.path =~ %r{/search$}i }
end

Do note that includes take priority over any excludes specified.

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request