An easy and unobtrusive way to use jQuery's autocomplete with Rails 3
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An easy way to use jQuery's autocomplete with Rails 3.

In now supports both ActiveRecord and mongoid.

It also supports Formtastic


You can find a detailed example on how to use this gem with ActiveRecord here.


You can find a detailed example on how to use this gem with MongoID here. (Same thing, different branch)

Before you start

Make sure your project is using jQuery-ui with the autocomplete widget before you continue.

You can find more info about that here:

I'd encourage you to understand how to use those 3 amazing tools before attempting to use this gem.


Include the gem on your Gemfile

gem 'rails3-jquery-autocomplete'

Install it

bundle install

Run the generator

rails generate autocomplete

And include autocomplete-rails.js on your layouts

javascript_include_tag "autocomplete-rails.js"

Upgrading from older versions

If you are upgrading from a previous version, run the generator after installing to replace the javascript file.

rails generate autocomplete

I'd recommend you do this every time you update to make sure you have the latest JS file.


Model Example

Assuming you have a Brand model:

class Brand < ActiveRecord::Base

create_table :brand do |t|
  t.column :name, :string


To set up the required action on your controller, all you have to do is call it with the class name and the method as in the following example:

class ProductsController < Admin::BaseController
  autocomplete :brand, :name

This will create an action autocomplete_brand_name on your controller, don't forget to add it on your routes file

resources :products do
  get :autocomplete_brand_name, :on => :collection


:full => true

By default, the search starts from the beginning of the string you're searching for. If you want to do a full search, set the full parameter to true.

class ProductsController < Admin::BaseController
  autocomplete :brand, :name, :full => true

The following terms would match the query 'un':

  • Luna
  • Unacceptable
  • Rerun

:full => false (default behavior)

Only the following terms mould match the query 'un':

  • Unacceptable


If you want to display a different version of what you're looking for, you can use the :display_value option.

This options receives a method name as the parameter, and that method will be called on the instance when displaying the results.

class Brand < ActiveRecord::Base
  def funky_method

class ProductsController < Admin::BaseController
  autocomplete :brand, :name, :display_value => :funky_method

In the example above, you will search by name, but the autocomplete list will display the result of funky_method

This wouldn't really make much sense unless you use it with the :id_element HTML tag. (See below)


On your view, all you have to do is include the attribute autocomplete on the text field using the url to the autocomplete action as the value.

form_for @product do |f|
  f.autocomplete_field :brand_name, autocomplete_brand_name_products_path

This will generate an HTML tag that looks like:

<input type="text" data-autocomplete="products/autocomplete_brand_name">

If you are not using a FormBuilder (form_for) or you just want to include an autocomplete field without the form, you can use the autocomplete_field_tag helper.

form_tag 'some/path'
  autocomplete_field_tag 'address', '', address_autocomplete_path, :size => 75

Now your autocomplete code is unobtrusive, Rails 3 style.

Getting the object id

If you need to use the id of the selected object, you can use the :id_element HTML tag too:

f.autocomplete_field :brand_name, autocomplete_brand_name_products_path, :id_element => '#some_element'

This will update the field with id *#some_element with the id of the selected object. The value for this option can be any jQuery selector.


If you are using Formtastic, you automatically get the autocompleted_input helper on semantic_form_for:

semantic_form_for @product do |f|
  f.autocompleted_input :brand_name, :url => autocomplete_brand_name_path

The only difference with the original helper is that you must specify the autocomplete url using the :url option.


I have created a step to test your autocomplete with Cucumber and Capybara, all you have to do is add the following lines to your env.rb file:

require 'cucumber/autocomplete'

Then you'll have access to the following step:

I choose "([^"]*)" in the autocomplete list

An example on how to use it:

Scenario: Autocomplete
  Given the following brands exists:
    | name  |
    | Alpha |
    | Beta  |
    | Gamma |
  And I go to the home page
  And I fill in "Brand name" with "al"
  And I choose "Alpha" in the autocomplete list
  Then the "Brand name" field should contain "Alpha"

I have only tested this using Capybara, no idea if it works with something else, to see it in action, check the example app.


If you want to make changes to the gem, first install bundler 1.0.0:

gem install bundler

And then, install all your dependencies:

bundle install

Running the test suite

You need to have an instance of MongoDB running on your computer or all the mongo tests will fail miserably.

rake test


  • 0.5.1 Add STI support
  • 0.5.0 Formtastic support
  • 0.4.0 MongoID support
  • 0.3.6 Using .live() to put autocomplete on dynamic fields

About the Author

Crowd Interactive is an American web design and development company that happens to work in Colima, Mexico. We specialize in building and growing online retail stores. We don’t work with everyone – just companies we believe in. Call us today to see if there’s a fit. Find more info here!