A tagging plugin for Mongoid that allows for custom tagging along dynamic contexts with real-time aggregation (pre-aggregated).
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Mongoid Taggable With Context

A tagging lib for Mongoid that allows for custom tagging along dynamic contexts. This lib was originally based on Mongoid Taggable by Wilker Lúcio and Ches Martin. It has evolved substantially since that point, but all credit goes to them for the initial tagging functionality.

For instance, in a social network, a user might have tags that are called skills, interests, sports, and more. There is no real way to differentiate between tags and so an implementation of this type is not possible with Mongoid Taggable.

Another example, aggregation such as counting tag occurrences was achieved by map-reduce with Mongoid Taggable. It was ok for small amount of tags, but when the amount of tags and documents grow, the original Mongoid Taggable won't be able to scale to real-time statistics demand.

Enter Mongoid Taggable With Context. Rather than tying functionality to a specific keyword (namely “tags”), Mongoid Taggable With Context allows you to specify an arbitrary number of tag “contexts” that can be used locally or in combination in the same way Mongoid Taggable was used.

Mongoid Taggable With Context also provides flexibility on aggregation strategy. In addition to the map-reduce strategy, Mongoid Taggable With Context also comes with real-time strategy. By using real-time strategy, your document can quickly adjusts the aggregation collection whenever tags are inserted or removed with $inc operator. So performance won't be impacted as the number of tags and documents grow.


You can simply install from rubygems:

gem install mongoid_taggable_with_context

or in Gemfile:

gem 'mongoid_taggable_with_context'

Basic Usage

To make a document taggable you need to include Mongoid::TaggableOnContext into your document and call the taggable macro with optional arguments:

class Post
  include Mongoid::Document
  include Mongoid::TaggableWithContext

  field :title
  field :content

  # default context is 'tags'.
  # This creates #tags, #tags=, #tags_array, #tags_array= instance methods
  # separator is " " by default
  # #tags method returns space separated string
  # #tags= methods accepts space separated string
  # #tags_array method returns an array of tags
  # #tags_array= method accepts an array of tags
  # #tags and #tags_array are automatically synched.

  # tagging for 'interests' context.
  # This creates #interests, #interests=, #interests_array, #interests_array= instance methods
  taggable :interests

  # tagging for 'skills' context.
  # This creates #skills, #skills=, #skills_array, #skills_array= instance methods
  # changing tag separator to "," (Default is " ") 
  taggable :skills, :separator => ','

Then in your form, for example:

<% form_for @post do |f| %>
    <%= f.label :title %><br />
    <%= f.text_field :title %>
    <%= f.label :content %><br />
    <%= f.text_area :content %>
    <%= f.label :tags %><br />
    <%= text_field_tag 'post[tags]' %>
    <%= f.label :interests %><br />
    <%= text_field_tag 'post[interests]' %>
    <%= f.label :skills %><br />
    <%= text_field_tag 'post[skills]' %>
    <button type="submit">Send</button>
<% end %>

Aggregation Strategies

By including an aggregation strategy in your document, tag aggregations will be automatically available to you. This lib presents the following aggregation strategies:

  • MapReduce

  • RealTime

The following document will automatically aggregate counts on all tag contexts.

class Post
  include Mongoid::Document
  include Mongoid::TaggableWithContext

  # automatically adds real time aggregations to all tag contexts
  include Mongoid::TaggableWithContext::AggregationStrategy::RealTime

  # alternatively for map-reduce
  # include Mongoid::TaggableWithContext::AggregationStrategy::MapReduce

  field :title
  field :content

  taggable :interests
  taggable :skills, :separator => ','

When you include an aggregation strategy, your document also gains a few extra methods to retrieve aggregation data. In the case of previous example the following methods are included:


Here is how to use these methods in more detail:

Post.create!(:tags => "food,ant,bee")
Post.create!(:tags => "juice,food,bee,zip")
Post.create!(:tags => "honey,strip,food")

Post.tags # will retrieve ["ant", "bee", "food", "honey", "juice", "strip", "zip"]
Post.tags_with_weight # will retrieve:
# [
#   ['ant', 1],
#   ['bee', 2],
#   ['food', 3],
#   ['honey', 1],
#   ['juice', 1],
#   ['strip', 1],
#   ['zip', 1]
# ]

Changing default separator

To change the default separator you may pass a separator argument to the macro:

class Post
  include Mongoid::Document
  include Mongoid::TaggableWithContext

  field :title
  field :content

  taggable :separator => ','    # tags will be delineated by comma instead of space

Development and Testing

Mongoid Taggable With Context uses Bundler for easy installation of development dependent gems. To get all dependent gems for development, while inside mongoid_taggable_with_context directory:

bundle install

Mongoid Taggable With Context uses RSpec for its test coverage. Inside mongoid_taggable_with_context directory, you can run the specs with:

rake spec

To see the test coverage, you need to be on ruby 1.8.7 (since latest rcov doesn't work 1.9) and run the following command:

rake rcov

Next Up

  • More documentation.

  • More Strategies. ( Let me know what kind of strategies you want, or contribute your own. )