Mongoid Search

Mongoid Search is a simple full text search implementation for Mongoid ORM. It supports Mongoid 3, 4, 5 and 6 and performs well for small data sets. If your searchable model is big (i.e. 1.000.000+ records), mongoid_fulltext, ElasticSearch, Solr or Sphinx may suit you better.

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In your Gemfile:

gem 'mongoid_search'


bundle install


class Product
  include Mongoid::Document
  include Mongoid::Search
  field :brand
  field :name
  field :info, type: Hash

  has_many   :tags
  belongs_to :category

  search_in :brand, :name, tags: :name, category: :name, info: %i[summary description]

class Tag
  include Mongoid::Document
  field :name

  belongs_to :product

class Category
  include Mongoid::Document
  field :name

  has_many :products

Now when you save a product, you get a _keywords field automatically:

p = brand: 'Apple', name: 'iPhone', info: { summary: 'Info-summary', description: 'Info-description' }
p.tags << 'Amazing')
p.tags << 'Awesome')
p.tags << 'Superb')
# => true
# => ["amazing", "apple", "awesome", "iphone", "superb", "Info-summary", "Info-description"]

Now you can run search, which will look in the _keywords field and return all matching results:

Product.full_text_search("apple iphone").size
# => 1

Note that the search is case insensitive, and accept partial searching too:

# => 1

Assuming you have a category with multiple products you can use the following code to search for 'iphone' in products cheaper than $499.

category.products.where( => 499).full_text_search('iphone').asc(:price)

To index or reindex all existing records, run this rake task

$ rake mongoid_search:index



  • :any - match any occurrence
  • :all - match all occurrences

Default is :any.

Product.full_text_search('apple motorola', match: :any).size
# => 1

Product.full_text_search('apple motorola', match: :all).size
# => 0
  • true - will return Model.all
  • false - will return []

Default is false.

Product.full_text_search('', allow_empty_search: true).size
# => 1
  • true - adds relevance information to the results
  • false - no relevance information

Default is false.

Product.full_text_search('amazing apple', relevant_search: true)
# => [#<Product _id: 5016e7d16af54efe1c000001, _type: nil, brand: "Apple", name: "iPhone", attrs: nil, info: nil, category_id: nil, _keywords: ["amazing", "apple", "awesome", "iphone", "superb"], relevance: 2.0>]

Please note that relevant_search will return an Array and not a Criteria object. The search method should always be called in the end of the method chain.


Alternatively, you can create an initializer to setup those options:

Mongoid::Search.setup do |config|
  ## Default matching type. Match :any or :all searched keywords
  config.match = :any

  ## If true, an empty search will return all objects
  config.allow_empty_search = false

  ## If true, will search with relevance information
  config.relevant_search = false

  ## Stem keywords
  config.stem_keywords = false

  ## Add a custom proc returning strings to replace the default stemmer
  # For example using ruby-stemmer:
  # config.stem_proc = { |word| Lingua.stemmer(word, :language => 'nl') }

  ## Words to ignore
  config.ignore_list = []

  ## An array of words
  # config.ignore_list = %w{ a an to from as }

  ## Or from a file
  # config.ignore_list = YAML.load( + '/config/ignorelist.yml'))["ignorelist"]

  ## Search using regex (slower)
  config.regex_search = true

  ## Regex to search

  ## Match partial words on both sides (slower)
  config.regex = { |query| /#{query}/ }

  ## Match partial words on the beginning or in the end (slightly faster)
  # config.regex = { |query| /^#{query}/ }
  # config.regex = { |query| /#{query}$/ }

  # Ligatures to be replaced
  config.ligatures = { "œ"=>"oe", "æ"=>"ae" }

  # Strip symbols regex to be replaced. These symbols will be replaced by space
  config.strip_symbols = /[._:;'\"`,?|+={}()[email protected]#%^&*<>~\$\-\\\/\[\]]/

  # Strip accents regex to be replaced. These sybols will be removed after strip_symbols replacing
  config.strip_accents = /[^\s\p{Alnum}]/

  # Minimum word size. Words smaller than it won't be indexed
  config.minimum_word_size = 2