Unobtrusive JS Form Extensions for rails 3.1
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Unobtrusive Javascript Form Extensions for Rails 3

Edifice-widgets is a companion gem to edifice which improves and simplifies your experience writing forms for rails.

Note that it does not depend on edifice, although it complements it well.


To install, simply add to your Gemfile:

gem 'edifice-forms'

To include the javascript, add to your application.js:

 *= require edifice-forms

Extending remote forms to handle errors

Rails 3 includes the excellent Unobtrusive JS, which allows us to define remote forms unobtrusively:

<form data-remote="true">

This will result in the form submitting via AJAX, however there is no support for errors in the form. This is surprising as the convention for rails form errors is clearly defined; return a HTML status 422 (:unprocessible_entity). In fact this is what the responds_with responder will do (for non-AJAX requests):

# Super-lean Rails controllers do it for me
class UsersController
  def update
    respond_with @user = User.update(params[:user])

edifice-forms extends this convention to AJAX requests. Firstly, we augment rails to respond with a 422 on invalid AJAX updates. Secondly, we add a data-form attribute:

<%= form_for @user, :remote => true, :html => {:'data-form' => 'show_errors'} do |f| %>

Now, when your users controller returns an error + an updated form with the errors highlighted, we'll automatically replace the form with the 'errored' version. Not a single line of Javascript required for such a common behaviour!


What about if your form returns data in JSON? We've got you covered. In order for remote JSON forms to show errors, we've written a small jQuery plugin: rails_form.js. It is written to conform to the conventions laid down by actionpack.

For instance, if you have, in your view:

  <label for="user[name]"></label>
  <input name="user[name]" value="Tom"></input>

You can call:

$('form').rails_form('add_error', 'user[name]', 'needs a surname');

Which will result in:

  <div class="field_with_errors">
    <label for="user[name]"></label>
  <div class="formError">needs a surname</div>
  <div class="field_with_errors">
    <input name="user[name]" value="Tom"></input>

The error can be removed with:

$('form').rails_form('clear_error', 'user[name]');

We've also added a convention that rails seemed to leave out, if you prefer your errors to be co-located:

<%= render_errors(f) >

Which will output something like:

<ul class="errors">
  <li data-for="name">Name needs a surname</li>

Forms with show_errors set will detect such a structure and update it on AJAX errors.

Use at your discretion.


The final piece of the puzzle is perhaps the most useful. Suppose you have a form on your site which isn't backed by a model. A good example is a feedback form. The feedback 'model' doesn't need to persist, it simply needs to send an email when it successfully saves; but we would still like to have all the ActiveModel goodness (validations, callbacks, etc) of a real ActiveRecord model. Enter the FormModel:

class Feedback < Edifice::Forms::FormModel
  attr_accessor :message
  attr_accessor :email

  # some simple validators
  validates :email, :presence => true, :format => {:with => /^.+@.+\..+$/}
  validates :message, :presence => true
  after_save :deliver_feedback
  # if validations pass and we successfully save, go ahead and deliver the 
  # feedback email to us, so we can read it.
  def deliver_feedback

Looks a lot like a ActiveRecord model, doesn't it? We get to write our controllers in the same super skinny way:

class FeedbacksController < ApplicationController
  def new
    respond_with @feedback =
  def create
    respond_with @feedback = Feedback.create params[:feedback]

Don't worry, we can use the @feedback in our views just as we would with a real model:

<%= form_for @feedback, :remote => true, 
      :html => {:'data-form' => 'show_errors'} do |f| %>
  <%= f.label :message, 'Your Feedback' %>
  <%= f.error_message_on :message %>
  <%= f.text_area :message, :placeholder => 'How can we help?' %>
<% end %>

Simple, huh?


Edifice is crafted by Percolate Studio and released under the MIT license