mongoid_flaggable is a lightweight and powerful way to add flags/tags (boolean values) to your mongoid models.

Install directly from rubygems:

gem install mongoid_flaggable

Or if you are using a Gemfile, place this in your Gemfile:

gem 'mongoid_flaggable'

This gem was created to give developers an easy way to flag mongoid models with boolean values. Flags are well-suited for temporary boolean values that do not merit the overhead of an additional field on the model and in the database. This includes gradual feature rollouts (whitelisting certain users for experimental features) and temporary metadata useful for analytics. Flags are not well-suited for data you intend to persist on your documents long-term.

One line of code is needed to set up a model with mongoid_flaggable.

class Book
    include Mongoid::Document
    include Mongoid::Flaggable         # it's this one
end

Be sure to run rake db:mongoid:create_indexes after adding mongoid_flaggable to a model. This will create an index on the flag_array field it makes use of.

book = Book.create
book.flags                             #=> []
book.add_flag!(:out_of_print)
book.flags                             #=> ["out_of_print"]
book.flag?(:out_of_print)              #=> true
book.flag?(:florinese_translation)     #=> false
book.remove_flag!(:out_of_print)
book.flags                             #=> []

• All methods accept "strings" or :symbols. The arguments are cast to strings before being used.
• Methods that end in a ! will immediately write to the database. Methods without the bang will make updates in memory (if the intention of the method is to update data), but will not persist the changes (i.e. after calling book.add_flag(:out_of_print), you must call book.save to persist the new flag).

Add a flag to a specific model without saving

book.add_flag(:out_of_print)

Add a flag to a specific model and save immediately

book.add_flag!(:out_of_print)

Remove a flag from a specific model without saving

book.remove_flag(:out_of_print)

Remove a flag from a specific model and save immediately

book.remove_flag!(:out_of_print)

Clear all flags from a specific model without saving

book.clear_flags

Clear all flags from a specific model and save immediately

book.clear_flags!

Get array of flags from a model - guaranteed to return an array or zero or more strings

book.flags   # => ["out_of_print"]

Test for the presence of a flag

book.flag?(:out_of_print)

Test for the presence of any of multiple flags

book.any_flags?(:out_of_print, :florinese_translation)

Test for the presence of all of multiple flags

book.all_flags?(:out_of_print, :florinese_translation)

• All finders return a Mongoid::Criteria that may be chained with additional clauses (e.g. where, limit, skip, order_by, etc.)

Retrieve documents with a given flag

Book.by_flag(:out_of_print)

Retrieve documents with any of multiple flags

Book.by_any_flags(:out_of_print, :florinese_translation)

Retrieve documents with all of multiple flags

Book.by_all_flags(:out_of_print, :florinese_translation)

Get the number of documents with a given flag

Book.flag_count(:out_of_print)

Get the number of documents with all of multiple flags

Book.flag_count(:out_of_print, :florinese_translation)

Get an array of all the distinct flags in use on the collection

Book.distinct_flags

Add a flag to multiple documents matching given criteria

Book.bulk_add_flag!(:out_of_print, {:last_printed_at.lt => 20.years.ago})

Remove a flag from multiple documents matching given criteria

Book.bulk_remove_flag!(:out_of_print, {author_name: "William Goldman"})

Remove a flag from all documents

Book.bulk_remove_flag!(:out_of_print)

Get a sorted frequency hash of all flags used on a collection

Book.flag_frequency           #=> {"out_of_print" => 20, "florinese_translation" => 5}

1. Fork it
2. Make your changes
3. Write/update tests. Run with rake.
4. Issue a Pull Request

MIT. Go nuts.