simple unobstrusive autocomplete
JS-library-independent
Controller and Model helpers

Install

As Rails plugin: rails plugin install git://github.com/grosser/simple_auto_complete.git Or As Gem: gem install simple_autocomplete

Then copy javascripts/css from example folder OR use your own

Examples

Controller

By default, autocomplete_for limits the results to 10 entries,
and sorts by the autocomplete field.

class UsersController < ApplicationController
  autocomplete_for :user, :name
end

autocomplete_for takes a third parameter, an options hash which is used in the find:

autocomplete_for :user, :name, :limit => 15, :order => 'created_at DESC'

With :match option you can filter for different columns

# find and order with firstname/lastname
# return full_name of records for auto-completion
autocomplete_for :user, :full_name, :match => [:firstname, :lastname]

With :query and :mask option you can change the generated query

# default: "LOWER(full_name) LIKE('%peter%')"
# now:     "full_name LIKE('peter%') AND deleted_at IS NULL"
autocomplete_for :user, :full_name, :query => "%{field} LIKE(%{query}) AND deleted_at IS NULL", :mask => '%{value}%'

With a block you can generate any output you need (ERB allowed):

autocomplete_for :post, :title do |items|
  items.map{|item| "#{item.title} -- #{item.id} <%= Time.now %>"}.join("\n")
end

The items passed into the block is an ActiveRecord scope allowing further scopes to be chained:

autocomplete_for :post, :title do |items|
  items.for_user(current_user).map(&:title).join("\n")
end

View

<%= f.text_field :auto_user_name, :class => 'autocomplete', 'data-autocomplete-url'=>autocomplete_for_user_name_users_path %>

Routes

map.resources :users, :collection => { :autocomplete_for_user_name => :get}

JS

use any library you like
(includes examples for jquery jquery.js + jquery.autocomplete.js + jquery.autocomplete.css)

jQuery(function($){//on document ready
  //autocomplete
  $('input.autocomplete').each(function(){
    var $input = $(this);
    $input.autocomplete($input.attr('data-autocomplete-url'));
  });
});

Records (Optional)

converts an auto_complete form field to an association on assignment
Tries to find the record by using find_by_autocomplete_xxx on the records model
unfound record -> nil
blank string -> nil
Controller find works independent of this find

Example for a post with autocompleted user name:

class User
  find_by_autocomplete :name # User.find_by_autocomplete_name('Michael')
end

class Post
  has_one :user
  autocomplete_for(:user, :name) #--> f.text_field :auto_user_name
  # OR
  autocomplete_for(:user, :name, :name=>:creator) #--> f.text_field :auto_creator_name (creator must a an User)
end

class Group
  has_many :users
  add_by_autocomplete(:user, :name) #--> f.text_field :add_by_auto_user_name
end

Authors

Inspired by DHH`s 'obstrusive' autocomplete_plugin.

Contributors

Michael Grosser
michael@grosser.it
Hereby placed under public domain, do what you want, just do not hold me accountable...