Transparent manipulation of bitmask attributes for ActiveRecord, based on the bitmask-attribute gem, which has been dormant since 2009. This updated gem work with Rails 3 and up (including Rails 3.1).
The best way to install is with RubyGems:
$ [sudo] gem install bitmask_attributes
Or better still, just add it to your Gemfile:
Simply declare an existing integer column as a bitmask with its possible values.
class User < ActiveRecord::Base bitmask :roles, :as => [:writer, :publisher, :editor, :proofreader] end
You can then modify the column using the declared values without resorting to manual bitmasks.
user = User.create(:name => "Bruce", :roles => [:publisher, :editor]) user.roles # => [:publisher, :editor] user.roles << :writer user.roles # => [:publisher, :editor, :writer]
It's easy to find out if a record has a given value:
user.roles?(:editor) # => true
You can check for multiple values (uses an
user.roles?(:editor, :publisher) # => true user.roles?(:editor, :proofreader) # => false
Or, just check if any values are present:
user.roles? # => true
You can get the list of values for any given attribute:
User.values_for_roles # => [:writer, :publisher, :editor, :proofreader]
A couple useful named scopes are also generated when you use
User.with_roles # => (all users with roles) User.with_roles(:editor) # => (all editors) User.with_roles(:editor, :writer) # => (all users who are BOTH editors and writers) User.with_any_roles(:editor, :writer) # => (all users who are editors OR writers)
Find records without any bitmask set:
User.without_roles # => (all users without a role) User.no_roles # => (all users without a role)
Find records without a specific attribute.
User.without_roles(:editor) # => (all users who are not editors)
Note that "without_" only supports a single attribute argument, and the "no_" method does not support arguments.
You can add your own methods to the bitmasked attributes (similar to named scopes):
bitmask :other_attribute, :as => [:value1, :value2] do def worked? true end end user = User.first user.other_attribute.worked? # => true
Warning: Modifying possible values
IMPORTANT: Once you have data using a bitmask, don't change the order
of the values, remove any values, or insert any new values in the
array anywhere except at the end. You won't like the results.
- Fork it.
- Create a branch (
git checkout -b new-feature)
- Make your changes
- Run the tests (
bundle exec rake)
- Commit your changes (
git commit -am "Created new feature")
- Push to the branch (
git push origin new-feature)
- Create a Pull Request from your branch.
- Promote it. Get others to drop in and +1 it.
Thanks to Bruce Williams and the following contributors of the bitmask-attribute plugin:
Copyright (c) 2007-2009 Bruce Williams & 2011 Joel Moss. See LICENSE for details.