Ransack

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Ransack is a rewrite of MetaSearch created by Ernie Miller and maintained by Ryan Bigg, Jon Atack and a great group of contributors. While it supports many of the same features as MetaSearch, its underlying implementation differs greatly from MetaSearch, and backwards compatibility is not a design goal.

Ransack enables the creation of both simple and advanced search forms for your Ruby on Rails application (demo source code here). If you're looking for something that simplifies query generation at the model or controller layer, you're probably not looking for Ransack (or MetaSearch, for that matter). Try Squeel instead.

If you're viewing this at github.com/activerecord-hackery/ransack, you're reading the documentation for the master branch with the latest features. View documentation for the last release (1.5.1).

Getting started

Ransack is compatible with Rails 3 and 4 (including 4.2) on Ruby 1.9 and later. We try to keep it functioning with Rails master as well. Ransack works out-of-the-box with Active Record and features new support for Mongoid 4.0 (without associations, further details below). If you are on Ruby 1.8, you may need to use a slightly earlier version of Ransack, like '< 1.4'.

In your Gemfile, for the last officially released Ransack gem:

gem 'ransack'

Or, if you would like to use the latest updates, use the master branch:

gem 'ransack', github: 'activerecord-hackery/ransack'

The other branches (rails-4, rails-4.1, and rails-4.2) were each used for developing and running Ransack with the latest upcoming version of Rails at the time. They are smaller and possibly slightly faster because they do not have to support previous versions of Rails and Active Record. Once support for that Rails version is merged from the branch into Ransack master, the branch is no longer actively maintained -- unless the open source community submits pull requests to maintain them. You are welcome to do so!

To use one of the branches, for example the rails-4.1 branch:

gem 'ransack', github: 'activerecord-hackery/ransack', branch: 'rails-4.1'

Usage

Ransack can be used in one of two modes, simple or advanced.

Simple Mode

This mode works much like MetaSearch, for those of you who are familiar with it, and requires very little setup effort.

If you're coming from MetaSearch, things to note:

  1. The default param key for search params is now :q, instead of :search. This is primarily to shorten query strings, though advanced queries (below) will still run afoul of URL length limits in most browsers and require a switch to HTTP POST requests. This key is configurable.

  2. form_for is now search_form_for, and validates that a Ransack::Search object is passed to it.

  3. Common ActiveRecord::Relation methods are no longer delegated by the search object. Instead, you will get your search results (an ActiveRecord::Relation in the case of the ActiveRecord adapter) via a call to Search#result.

  4. If passed distinct: true, result will generate a SELECT DISTINCT to avoid returning duplicate rows, even if conditions on a join would otherwise result in some. It generates the same SQL as calling uniq on the relation.

Please note that for many databases, a sort on an associated table's columns may result in invalid SQL with distinct: true -- in those cases, you're on your own, and will need to modify the result as needed to allow these queries to work.

If distinct: true or uniq is causing invalid SQL, another way to remove duplicates is to call to_a.uniq on the collection at the end (see the next section below) -- with the caveat that the de-duping is taking place in Ruby instead of in SQL, which is potentially slower and uses more memory, and that it may display awkwardly with pagination if the number of results is greater than the page size.

In your controller

def index
  @q = Person.search(params[:q])
  @people = @q.result(distinct: true)
end

or without distinct:true, for sorting on an associated table's columns (in this example, with preloading each Person's Articles and pagination):

def index
  @q = Person.search(params[:q])
  @people = @q.result.includes(:articles).page(params[:page])

  # or use `to_a.uniq` to remove duplicates (can also be done in the view):
  @people = @q.result.includes(:articles).page(params[:page]).to_a.uniq
end

In your view

The two primary Ransack view helpers are search_form_for and sort_link, which are defined in Ransack::Helpers::FormHelper.

Ransack's search_form_for helper replaces form_for for creating the view search form:
<%= search_form_for @q do |f| %>

  # Search if the name field contains...
  <%= f.label :name_cont %>
  <%= f.search_field :name_cont %>

  # Search if an associated articles.title starts with...
  <%= f.label :articles_title_start %>
  <%= f.search_field :articles_title_start %>

  # Attributes may be chained. Search multiple attributes for one value...
  <%= f.label :name_or_description_or_email_or_articles_title_cont %>
  <%= f.search_field :name_or_description_or_email_or_articles_title_cont %>

  <%= f.submit %>
<% end %>

cont (contains) and start (starts with) are just two of the available search predicates. See Constants for a full list and the wiki for more information.

The search_form_for answer format can be set like this: ```erb <%= search_form_for(@q, format: :pdf) do |f| %>

<%= search_form_for(@q, format: :json) do |f| %> ```

Ransack's sort_link helper creates table headers that are sortable links:
<%= sort_link(@q, :name) %>

Additional options can be passed after the column attribute, like a different column title or a default sort order:

<%= sort_link(@q, :name, 'Last Name', default_order: :desc) %>

With a polymorphic association, you may need to specify the name of the link explicitly to avoid an uninitialized constant Model::Xxxable error (see issue #421):

<%= sort_link(@q, :xxxable_of_Ymodel_type_some_attribute, 'Attribute Name') %>

You can also sort on multiple fields by specifying an ordered array:

<%= sort_link(@q, :last_name, [:last_name, 'first_name asc'], 'Last Name') %>

In the example above, clicking the link will sort by last_name and then first_name. Specifying the sort direction on a field in the array tells Ransack to always sort that particular field in the specified direction.

Multiple default_order fields may also be specified with a hash:

<%= sort_link(@q, :last_name, %i(last_name first_name),
  default_order: { last_name: 'asc', first_name: 'desc' }) %>

This example toggles the sort directions of both fields, by default initially sorting the last_name field by ascending order, and the first_name field by descending order.

The sort link may be displayed without the order indicator arrow by passing hide_indicator: true:

<%= sort_link(@q, :name, hide_indicator: true) %>

Advanced Mode

"Advanced" searches (ab)use Rails' nested attributes functionality in order to generate complex queries with nested AND/OR groupings, etc. This takes a bit more work but can generate some pretty cool search interfaces that put a lot of power in the hands of your users. A notable drawback with these searches is that the increased size of the parameter string will typically force you to use the HTTP POST method instead of GET. :(

This means you'll need to tweak your routes...

resources :people do
  collection do
    match 'search' => 'people#search', via: [:get, :post], as: :search
  end
end

... and add another controller action ...

def search
  index
  render :index
end

... and update your search_form_for line in the view ...

<%= search_form_for @q, url: search_people_path,
                        html: { method: :post } do |f| %>

Once you've done so, you can make use of the helpers in Ransack::Helpers::FormBuilder to construct much more complex search forms, such as the one on the demo page (source code here).

Ransack #search method

Ransack will try to to make #search available in your models, but in the case that #search has already been defined, you can use #ransack instead. For example, the following would be equivalent:

Article.search(params[:q])
Article.ransack(params[:q])

If Ransack's #search method conflicts with the name of another method named search in your code or another gem, it may be resolved either by patching the extended class_method in Ransack::Adapters::ActiveRecord::Base to remove the line alias :search :ransack unless base.respond_to? :search, or by placing the following line in your Ransack initializer file at config/initializers/ransack.rb:

Ransack::Adapters::ActiveRecord::Base.class_eval('remove_method :search')

Associations

You can easily use Ransack to search for objects in has_many and belongs_to associations.

Given you have these associations ...

class Employee < ActiveRecord::Base
  belongs_to :supervisor

  # has attributes first_name:string and last_name:string
end

class Department < ActiveRecord::Base
  has_many :supervisors

  # has attribute title:string
end

class Supervisor < ActiveRecord::Base
  belongs_to :department
  has_many :employees

  # has attribute last_name:string
end

... and a controller ...

class SupervisorsController < ApplicationController
  def index
    @q = Supervisor.search(params[:q])
    @supervisors = @q.result.includes(:department, :employees)
  end
end

... you might set up your form like this ...

<%= search_form_for @q do |f| %>
  <%= f.label :last_name_cont %>
  <%= f.search_field :last_name_cont %>

  <%= f.label :department_title_cont %>
  <%= f.search_field :department_title_cont %>

  <%= f.label :employees_first_name_or_employees_last_name_cont %>
  <%= f.search_field :employees_first_name_or_employees_last_name_cont %>

  <%= f.submit "search" %>
<% end %>
...
<%= content_tag :table do %>
  <%= content_tag :th, sort_link(@q, :last_name) %>
  <%= content_tag :th, sort_link(@q, 'departments.title') %>
  <%= content_tag :th, sort_link(@q, 'employees.last_name') %>
<% end %>

Using Ransackers to add custom search functions via Arel

The main premise behind Ransack is to provide access to Arel predicate methods. Ransack provides special methods, called ransackers, for creating additional search functions via Arel. More information about ransacker methods can be found here in the wiki. Feel free to contribute working ransacker code examples to the wiki!

Authorization (whitelisting/blacklisting)

By default, searching and sorting are authorized on any column of your model and no class methods/scopes are whitelisted.

Ransack adds four methods to ActiveRecord::Base that you can redefine as class methods in your models to apply selective authorization: ransackable_attributes, ransackable_associations, ransackable_scopes and ransortable_attributes.

Here is how these four methods are implemented in Ransack:

  # Ransackable_attributes, by default, returns all column names
  # and any defined ransackers as an array of strings.
  # For overriding with a whitelist array of strings.
  #
  def ransackable_attributes(auth_object = nil)
    column_names + _ransackers.keys
  end

  # Ransackable_associations, by default, returns the names
  # of all associations as an array of strings.
  # For overriding with a whitelist array of strings.
  #
  def ransackable_associations(auth_object = nil)
    reflect_on_all_associations.map { |a| a.name.to_s }
  end

  # Ransortable_attributes, by default, returns the names
  # of all attributes available for sorting as an array of strings.
  # For overriding with a whitelist array of strings.
  #
  def ransortable_attributes(auth_object = nil)
    ransackable_attributes(auth_object)
  end

  # Ransackable_scopes, by default, returns an empty array
  # i.e. no class methods/scopes are authorized.
  # For overriding with a whitelist array of *symbols*.
  #
  def ransackable_scopes(auth_object = nil)
    []
  end

Any values not returned from these methods will be ignored by Ransack, i.e. they are not authorized.

All four methods can receive a single optional parameter, auth_object. When you call the search or ransack method on your model, you can provide a value for an auth_object key in the options hash which can be used by your own overridden methods.

Here is an example that puts all this together, adapted from this blog post by Ernie Miller. In an Article model, add the following ransackable_attributes class method (preferably private):

class Article < ActiveRecord::Base

  private

  def self.ransackable_attributes(auth_object = nil)
    if auth_object == :admin
      # whitelist all attributes for admin
      super
    else
      # whitelist only the title and body attributes for other users
      super & %w(title body)
    end
  end
end

Here is example code for the articles_controller:

class ArticlesController < ApplicationController

  def index
    @q = Article.search(params[:q], auth_object: set_ransack_auth_object)
    @articles = @q.result
  end

  private

  def set_ransack_auth_object
    current_user.admin? ? :admin : nil
  end
end

Trying it out in rails console:

> Article
=> Article(id: integer, person_id: integer, title: string, body: text)

> Article.ransackable_attributes
=> ["title", "body"]

> Article.ransackable_attributes(:admin)
=> ["id", "person_id", "title", "body"]

> Article.search(id_eq: 1).result.to_sql
=> SELECT "articles".* FROM "articles"  # Note that search param was ignored!

> Article.search({ id_eq: 1 }, { auth_object: nil }).result.to_sql
=> SELECT "articles".* FROM "articles"  # Search param still ignored!

> Article.search({ id_eq: 1 }, { auth_object: :admin }).result.to_sql
=> SELECT "articles".* FROM "articles"  WHERE "articles"."id" = 1

That's it! Now you know how to whitelist/blacklist various elements in Ransack.

Using Scopes/Class Methods

Continuing on from the preceding section, searching by scopes requires defining a whitelist of ransackable_scopes on the model class. The whitelist should be an array of symbols. By default, all class methods (e.g. scopes) are ignored. Scopes will be applied for matching true values, or for given values if the scope accepts a value:

class Employee < ActiveRecord::Base
  scope :active, ->(boolean = true) { where(active: boolean) }
  scope :salary_gt, ->(amount) { where('salary > ?', amount) }

  # Scopes are just syntactical sugar for class methods, which may also be used:

  def self.hired_since(date)
    where('start_date >= ?', date)
  end

  private

  def self.ransackable_scopes(auth_object = nil)
    if auth_object.try(:admin?)
      # allow admin users access to all three methods
      %i(active hired_since salary_gt)
    else
      # allow other users to search on active and hired_since only
      %i(active hired_since)
    end
  end
end

Employee.search({ active: true, hired_since: '2013-01-01' })

Employee.search({ salary_gt: 100_000 }, { auth_object: current_user })

If the true value is being passed via url params or by some other mechanism that will convert it to a string (i.e. active: 'true' instead of active: true), the true value will not be passed to the scope. If you want to pass a 'true' string to the scope, you should wrap it in an array (i.e. active: ['true']).

Scopes are a recent addition to Ransack and currently have a few caveats: First, a scope involving child associations needs to be defined in the parent table model, not in the child model. Second, scopes with an array as an argument are not easily usable yet, because the array currently needs to be wrapped in an array to function (see this issue), which is not compatible with Ransack form helpers. For this use case, it may be better for now to use ransackers instead, where feasible. Pull requests with solutions and tests are welcome!

Grouping queries by OR instead of AND

The default AND grouping can be changed to OR by adding m: 'or' to the query hash.

You can easily try it in your controller code by changing params[:q] in the index action to params[:q].try(:merge, m: 'or') as follows:

def index
  @q = Artist.search(params[:q].try(:merge, m: 'or'))
  @artists = @q.result
end

Normally, if you wanted users to be able to toggle between AND and OR query grouping, you would probably set up your search form so that m was in the URL params hash, but here we assigned m manually just to try it out quickly.

Alternatively, trying it in the Rails console:

artists = Artist.search(name_cont: 'foo', style_cont: 'bar', m: 'or')
=> Ransack::Search<class: Artist, base: Grouping <conditions: [
  Condition <attributes: ["name"], predicate: cont, values: ["foo"]>,
  Condition <attributes: ["style"], predicate: cont, values: ["bar"]>
  ], combinator: or>>

artists.result.to_sql
=> "SELECT \"artists\".* FROM \"artists\"
    WHERE ((\"artists\".\"name\" ILIKE '%foo%'
    OR \"artists\".\"style\" ILIKE '%bar%'))"

The combinator becomes or instead of the default and, and the SQL query becomes WHERE...OR instead of WHERE...AND.

This works with associations as well. Imagine an Artist model that has many Memberships, and many Musicians through Memberships:

artists = Artist.search(name_cont: 'foo', musicians_email_cont: 'bar', m: 'or')
=> Ransack::Search<class: Artist, base: Grouping <conditions: [
  Condition <attributes: ["name"], predicate: cont, values: ["foo"]>,
  Condition <attributes: ["musicians_email"], predicate: cont, values: ["bar"]>
  ], combinator: or>>

artists.result.to_sql
=> "SELECT \"artists\".* FROM \"artists\"
    LEFT OUTER JOIN \"memberships\"
      ON \"memberships\".\"artist_id\" = \"artists\".\"id\"
    LEFT OUTER JOIN \"musicians\"
      ON \"musicians\".\"id\" = \"memberships\".\"musician_id\"
    WHERE ((\"artists\".\"name\" ILIKE '%foo%'
    OR \"musicians\".\"email\" ILIKE '%bar%'))"

Using SimpleForm

If you would like to combine the Ransack and SimpleForm form builders, set the RANSACK_FORM_BUILDER environment variable before Rails boots up, e.g. in config/application.rb before require 'rails/all' as shown below (and add gem 'simple_form' in your Gemfile).

require File.expand_path('../boot', __FILE__)
ENV['RANSACK_FORM_BUILDER'] = '::SimpleForm::FormBuilder'
require 'rails/all'

I18n

Ransack translation files are available in Ransack::Locale. You may also be interested in one of the many translations for Ransack available at http://www.localeapp.com/projects/2999.

Predicate and attribute translations in forms may be specified as follows (see the translation files in Ransack::Locale for more examples):

locales/en.yml: yml en: ransack: asc: ascending desc: descending predicates: cont: contains not_cont: not contains start: starts with end: ends with gt: greater than lt: less than attributes: person: name: Full Name article: title: Article Title body: Main Content

Attribute names may also be changed globally, or under activerecord:

en:
  attributes:
    model_name:
      model_field1: field name1
      model_field2: field name2
  activerecord:
    attributes:
      namespace/article:
        title: AR Namespaced Title
      namespace_article:
        title: Old Ransack Namespaced Title

Mongoid

Ransack now works with Mongoid in the same way as Active Record, except that with Mongoid, associations are not currently supported. A demo app may be found here and the demo source code is here. A result method called on a Ransack::Search returns a Mongoid::Criteria object:

  @q = Person.search(params[:q])
  @people = @q.result # => Mongoid::Criteria

  # or you can add more Mongoid queries
  @people = @q.result.active.order_by(updated_at: -1).limit(10)

Semantic Versioning

Ransack attempts to follow semantic versioning in the format of x.y.z, where:

x stands for a major version (new features that are not backward-compatible).

y stands for a minor version (new features that are backward-compatible).

z stands for a patch (bug fixes).

In other words: Major.Minor.Patch.

Contributions

To support the project:

  • Use Ransack in your apps, and let us know if you encounter anything that's broken or missing. A failing spec to demonstrate the issue is awesome. A pull request with passing tests is even better!
  • Before filing an issue or pull request, be sure to read and follow the Contributing Guide.
  • Please use Stack Overflow or other sites for questions or discussion not directly related to bug reports, pull requests, or documentation improvements.
  • Spread the word on Twitter, Facebook, and elsewhere if Ransack's been useful to you. The more people who are using the project, the quicker we can find and fix bugs!

Copyright

Copyright © 2011-2014 Ernie Miller