MinimalTags is a tiny gem for adding tagging support to Mongoid, ActiveRecord and Sequel.

Multiple tag fields can be used, each with their own way of formatting.

Please Note: ActiveRecord and Sequel both require PostgreSQL.

Add to your Gemfile:

gem 'minimal_tags'

There is nothing else to add, fields will be created when you define your tag fields.

Add the following migration for each tag field you want.

class AddTagsToPosts < ActiveRecord::Migration
  def change
    add_column :posts, :tags, :text, default: [], null: false, array: true
    add_index :posts, :tags, using: :gin
  end
end

Add the following migration for each tag field you want.

Sequel.migration do
  change do
    add_column :posts, :tags, 'text[]', default: [], null: false
    add_index :posts, :tags, type: :gin
  end
end

Also enable the pg_array and pg_array_ops extensions:

DB = Sequel.connect('postgres://...')
DB.extension :pg_array
Sequel.extension :pg_array_ops

Start by including the MinimalTags module and define your tag fields with the tag_field method.

class Document
  include Mongoid::Document
  include MinimalTags

  tag_field :tags
  tag_field :upcase_tags, formatter: UpcaseFormatter.new
end

You can define multiple tag fields, just ensure they have unique names.
Formatters can be defined on each tag field if needed, otherwise the default, MinimalTags::SimpleFormatter will be used.

MinimalTags.default_formatter = UnderscoreTagFormatter.new

The following scopes are also added for each tag field and can be chained: .any_*, .all_*, .without_any_*, .without_all_*

Document.any_tags(['a', 'b', 'c'])
Document.all_tags(['a', 'b', 'c'])
Document.without_any_tags(['a', 'b', 'c'])
Document.without_all_tags(['a', 'b', 'c'])

Sequel only for now

Find with partial tag match:

Document.partial_tags('hello').all

Array of matching tags:

Document.partial_tags('hello').select_map(:mt_tags)

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