The document describes how to implement ajax nested forms and ajax file uploads in a Rails application. It discusses using the jquery-rails, anjlab-bootstrap-rails, simple_form, carrierwave, and mini_magick gems. It provides code examples for models with a nested association and carrierwave file uploads, form views using simple_form, and JavaScript to handle ajax responses. The key aspects are using respond_with, rendering modal views, rendering partials, defining ajax callbacks, and requiring the cocoon and remotipart gems to enable nested forms and ajax file uploads respectively.

1. Ajax nested form &
Ajax upload in Rails
何澤清 Tse-Ching Ho
2012/08/21

2. About
• https://github.com/tsechingho
• https://twitter.com/tsechingho
• https://facebook.com/tsechingho

3. Demo Code
https://github.com/tsechingho/ajax-tutorial

4. Prerequisite Work

5. Gems supposed to
be well understood
• jquery-rails
• anjlab-bootstrap-rails
• simple_form
• carrierwave
• mini_magick / rmagick

6. Ground rails project
• Have two models associated with has_many
• Have one model mounted with carrierwave’s
uploader
• Render 'form' in views of new and edit
• Use respond_with for each action of controller
• Layout with twitter bootstrap

7. Twitter Bootstrap Modal

8. Handle Feedback
of .ajaxSubmit() via Modal
modal modal modal modal
Error
feedback Success
.feedback
modal feedback

9. Creature & CreaturePhoto
require 'file_size_validator'
class CreaturePhoto < ActiveRecord::Base
class Creature < ActiveRecord::Base
attr_accessible :content_type, :file_name, :file_size,
attr_accessible :characteristic, :place_of_origin,
:creature_id, :source, :source_cache, :remove_source
:popular_name, :scientific_name, :animal_handbook_ids
validates :source,
validates :popular_name, presence: true
file_size: {
maximum: 3.megabytes.to_i
has_many :animal_handbook_creatures
}
has_many :animal_handbooks,
through: :animal_handbook_creatures
mount_uploader :source,
has_many :photos, class_name: 'CreaturePhoto'
CreaturePhotoUploader, mount_on: :file_name
delegate :url, :current_path, :size, :filename, to: :source
def name
popular_name
belongs_to :creature
end
end
before_save :update_attributes_with_source
end

10. creatures_controller.rb
class CreaturesController < ApplicationController
before_filter :load_creature, only: [:show, :edit, :update, :destroy]
respond_to :html
def edit
render 'edit_modal', layout: false if request.xhr?
end
def update
@creature.update_attributes params[:creature]
if @creature.valid?
flash[:notice] = 'Creature was successfully updated.'
end
respond_with @creature do |format|
format.html {
if @creature.valid?
load_creatures
render partial: 'table', locals: { creatures: @creatures }
else
render 'edit_modal', layout: false
end
} if request.xhr?
end
flash.discard :notice if request.xhr?
end
end

11. twitter_bootstrap_helper.rb
def iconed_link_to(text, url, options = {})
icon_class = options.delete(:icon_class)
link_to url, options do
content_tag(:i, nil, class: icon_class) << ' ' << text
end
end
def link_to_edit(url, options = {})
icon_class = options.delete(:icon_class) || 'icon-edit'
default_options = { title: t('helpers.edit'), class: 'btn', icon_class: icon_class }
iconed_link_to nil, url, default_options.deep_merge(options)
end
def link_to_edit_modal(url, modal_id)
default_options = { remote: true, data: { target: modal_id, toggle: 'modal', type:
'html' }, class: 'btn modal-open' }
link_to_edit url, default_options
end

12. creatures/index.html.erb
<article id="creature-list">
<header>
<h1><%= t('.title') %></h1>
</header>
<%= render_list class: 'nav nav-tabs' do |li|
li << [link_to_open_modal(t('helpers.new'), new_creature_path, '#creature-
modal'), { class: 'action' }]
end %>
<%= render 'table', creatures: @creatures %>
<nav role="pagination">
</nav>
</article>
<div class="modal hide fade" id="creature-modal"></div>

13. creatures/_table.html.erb
<table class="table table-striped table-bordered">
<tr>
<th><%= Creature.human_attribute_name :popular_name %></th>
<th><%= Creature.human_attribute_name :scientific_name %></th>
<th><%= Creature.human_attribute_name :place_of_origin %></th>
<th><%= Creature.human_attribute_name :characteristic %></th>
<th><%= t('helpers.actions') %></th>
</tr>
<% creatures.each do |creature| %>
<tr>
<td><%= creature.popular_name %></td>
<td><%= creature.scientific_name %></td>
<td><%= creature.place_of_origin %></td>
<td><%= creature.characteristic %></td>
<td class="btn-group">
<%= link_to_show creature_path(creature) %>
<%= link_to_edit_modal edit_creature_path(creature), '#creature-modal' %>
<%= link_to_destroy creature_path(creature) %>
</td>
</tr>
<% end %>
</table>

14. creatures/edit_modal.html.erb
<%= simple_form_for @creature, remote: true, html: { data: { type: 'html' }, class:
'form-horizontal' } do |f| %>
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal">×</button>
<h3><%= t('.title') %></h3>
</div>
<div class="modal-body">
<%= render 'form', f: f %>
</div>
<div class="modal-footer">
<a href="#" class="btn" data-dismiss="modal"><%= t('helpers.close') %></a>
<%= f.button :submit, name: nil, class: 'btn-primary' %>
</div>
<% end %>

15. modal.js.coffee
$ ->
$.modal ||= {}
$.modal.appendFeedback = (modal, data) ->
$('<div>').addClass('feedback hide').html(data).appendTo(modal)
$.modal.replaceFeedback = (modal) ->
modal.html(modal.children('.feedback').html())
$.modal.enableChosen()
$.modal.replaceTable = (table_id, modal = $(this)) ->
feedback_table = modal.find('.table')
table = $(table_id).find('.table')
table.html(feedback_table.html())
modal.find('.feedback').remove().end()
.modal('hide')
table.effect('shake')
return true

16. creatures.js.coffee
$ ->
$('#creature-list')
.on 'ajax:success', 'a.modal-open', (event, data, status, xhr) ->
modal = $($(this).attr('data-target'))
modal.html(data)
$.modal.enableChosen()
.on 'ajax:error', '.a.modal-open', (event, xhr, status, error) ->
modal = $($(this).attr('data-target'))
$.modal.showErrorModal(status, error, modal)
$('#creature-modal')
.on 'ajax:success', '.simple_form', (event, data, status, xhr) ->
modal = $(this).parent()
$.modal.appendFeedback(modal, data)
if modal.find('.feedback .alert-error').size() > 0
$.modal.replaceFeedback(modal)
return true
table_id = '#creature-list'
$.modal.replaceTable(table_id, modal)
.on 'ajax:error', '.simple_form', (event, xhr, status, error) ->
modal = $('#creature-modal')
$.modal.showErrorModal(status, error, modal)

17. application.js
//= require jquery
//= require jquery-ui
//= require jquery_ujs
//= require bootstrap
//= require chosen-jquery
//= require modal
//= require_tree .

18. Key Points
• Use respond_with
• Render 'modal' specific files
• Render partial files
• Via data attributes
• Define rails ajax callbacks
• Use namespace for javascript methods
• Catch ajax callback in div container if data-type
is :html

19. Ajax Nested Form

20. How To
• Concepts
• Save template in data attributes
• DOM manipulation
• https://github.com/nathanvda/cocoon
• gem 'cocoon'

21. creature.rb
class Creature < ActiveRecord::Base
attr_accessible :characteristic, :place_of_origin, :popular_name, :scientific_name,
:animal_handbook_ids, :photos_attributes
validates :popular_name, presence: true
has_many :animal_handbook_creatures
has_many :animal_handbooks, through: :animal_handbook_creatures
has_many :photos, class_name: 'CreaturePhoto'
accepts_nested_attributes_for :photos, allow_destroy: true, reject_if: proc
{ |obj| obj.blank? }
def name
popular_name
end
end

22. twitter_bootstrap_helper.rb
module TwitterBootstrapHelper
def iconed_link_to_add_association(text, *args)
args << {} if args.size < 2
icon_class = args.last.delete(:icon_class) || 'icon-plus'
default_options = { title: t('helpers.add'), class: 'btn' }
args.last.deep_merge! default_options
link_to_add_association *args do
content_tag(:i, nil, class: icon_class) << ' ' << text
end
end
def iconed_link_to_remove_association(text, *args)
args << {} if args.size < 2
icon_class = args.last.delete(:icon_class) || 'icon-remove'
default_options = { title: t('helpers.remove'), class: 'btn' }
args.last.deep_merge! default_options
link_to_remove_association *args do
content_tag(:i, nil, class: icon_class) << ' ' << text
end
end
end

23. creatures/_form.html.erb
<%= f.error_notification %>
<div class="form-inputs">
<%= f.input :popular_name %>
<%= f.input :scientific_name %>
<%= f.input :place_of_origin %>
<%= f.input :characteristic, input_html: { size: '20x5' } %>
<%= f.association :animal_handbooks, input_html: { class: 'chzn-select' } %>
</div>
<h3><%= t('.creature_photos') %></h3>
<div class="form-inputs form-inline">
<%= render 'creature_photos/field_labels', creature_form: f %>
<%= f.simple_fields_for :photos do |f2| %>
<%= render 'creature_photos/fields', f: f2 %>
<% end %>
</div>
<%= iconed_link_to_add_association t('helpers.add'),
f,
:photos,
data: {
:'association-insertion-node' => '.form-inputs.form-inline',
:'association-insertion-method' => :append
},
partial: 'creature_photos/fields',
render_options: {
locals: { }
} %>

24. creatures/_fields.html.erb
<%= field_set_tag nil, class: 'creature-fields row-fluid nested-form-hidden-label nested-fields' do %>
<%= f.input :popular_name, wrapper_html: { class: 'span2' }, input_html: { class: 'span12' } %>
<%= f.input :scientific_name, wrapper_html: { class: 'span2' }, input_html: { class: 'span12' } %>
<%= f.input :place_of_origin, wrapper_html: { class: 'span2' }, input_html: { class: 'span12' } %>
<%= f.input :characteristic, as: :string, wrapper_html: { class: 'span4' }, input_html: { class: 'span12' } %>
<div class="control-group actions span2">
<%= iconed_link_to_remove_association nil, f %>
</div>
<% end %>

25. application.js
//= require jquery
//= require jquery-ui
//= require jquery_ujs
//= require bootstrap
//= require chosen-jquery
//= require cocoon
//= require modal
//= require_tree .

26. Key Points
• accepts_nested_attributes_for :photos, allow_destroy:
true
• attr_accessible :photos_attributes
• Render partial file
• Use link_to_add_association helper
• Use link_to_remove_association helper
• Add 'nested-fields' class to container tag of nested item
• Require cocoon javascript

27. Ajax Upload
It’s impossible
since browsers forbid for security reason.
It’s possible if we cheat browsers.

28. How To
• Concepts
• iFrame Transport
• rack middleware to modify request header
• https://github.com/leppert/remotipart
• gem 'remotipart'

29. iFrame Transport
http://www.alfajango.com/blog/ajax-file-uploads-with-the-iframe-method/

30. application.js
//= require jquery
//= require jquery-ui
//= require jquery_ujs
//= require bootstrap
//= require chosen-jquery
//= require cocoon
// Since XMLHttpRequest (AJAX) standard has no support for file uploads,
// use iframe-transport method of remotipart gem for ajax file upload.
//= require jquery.remotipart
//= require modal
//= require_tree .

31. Other ways?
• iFrame
• https://github.com/blueimp/jQuery-File-Upload
• Flash
• http://www.uploadify.com
• Form Data
• http://hacks.mozilla.org/2010/07/firefox-4-
formdata-and-the-new-file-url-object/

32. References
• http://www.alfajango.com/blog/rails-3-remote-links-
and-forms/
• http://www.alfajango.com/blog/rails-3-remote-links-
and-forms-data-type-with-jquery/
• http://railscasts.com/episodes/196-nested-model-
form-revised
• http://www.alfajango.com/blog/ajax-file-uploads-with-
the-iframe-method/
• http://os.alfajango.com/remotipart/

33. THANKS