Transparent manipulation of bitmask attributes (Rails Compatible).
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
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)
Later we'll support an
or boolean; for now, do something like:
User.with_roles(:editor) + User.with_roles(:writer) # => (all users who are EITHER editors and writers)
Find records without any bitmask set:
User.without_roles # => (all users without a role)
Later we'll support finding records without a specific bitmask.
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.
Contributing and reporting issues
Please feel free to fork & contribute fixes via GitHub pull requests. The official repository for this project is http://github.com/bruce/bitmask-attribute
Issues can be reported at http://github.com/bruce/bitmask-attribute/issues
Thanks to the following contributors:
Copyright (c) 2007-2009 Bruce Williams. See LICENSE for details.