Auto-complete tagging with Rails, PostgreSQL Arrays and Chosen: A Complete Example

_form.html.erb

<%= f.label :name, 'Your Name' %>
<%= f.input :name, placeholder: 'John/Jane Doe' %>

<%= f.label :states_visited, 'States You\'ve Been To' %>
<%= f.select :states_visited, MURICA, {}, { multiple: true, class: 'taggable' } %>

application.css

*= require chosen

application.js

//= require chosen-jquery

application_controller.rb

class ApplicationController < ActionController::Base
  before_action :clean_select_multiple_params, only: [:create, :update]

  # existing stuff...
  
  private

  # Used to strip blank first values from array-type params.
  def clean_select_multiple_params hash = params
    hash.each do |key, value|
      case value
      when Array then value.reject!(&:blank?)
      when Hash then clean_select_multiple_params(value)
      end
    end
  end
end

console

rails g migration add_states_visited_to_people

forms.js.coffee

jQuery ->
  $('.taggable').chosen()

people_controller.rb

def person_params
  params.require(:person).permit(:name, { states_visited: [] })
end

show.html.erb

<h2>States I've Been To</h2>
<% if @person.states_visited.any? %>
  <ul>
    <% @person.states_visited.each do |state| %>
      <li><%= state %></li>
    <% end %>
  </ul>
<% end %>

states.rb

MURICA = ["Alabama", "Alaska", ..., "Wyoming"]

XYZ_add_states_visited_to_people.rb

class AddStatesVisitedToPeople < ActiveRecord::Migration
  def change
    add_column :people, :states_visited, :text, array: true, :default => []
  end
end