Can't get cocoon to work with Ruby on Rails 4

I have been struggling trying to get this to work for the past few hours and I just can't for some reason. I followed the steps almost exactly listed in the github repository link.

I created a new application using all of the following steps:

# rails new demo_app
# cd demo_app/
+++ added gem 'cocoon' to the Gemfile
+++ added //= require cocoon to the application.js file
# rails g scaffold Project name:string description:string
# rails g model Task description:string done:boolean project:belongs_to
+++ added has_many :tasks to the Project model
+++ added :_destroy to the permit in my projects_controller.rb file
# bundle install


Here is my views / projects / _form.html.erb file:

<%= form_for(@project) do |f| %>
  <% if @project.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@project.errors.count, "error") %> prohibited this project from being saved:</h2>

      <% @project.errors.full_messages.each do |message| %>
        <li><%= message %></li>
      <% end %>
  <% end %>

  <div class="field">
    <%= f.label :name %><br>
    <%= f.text_field :name %>
  <div class="field">
    <%= f.label :description %><br>
    <%= f.text_field :description %>
  <%= f.fields_for :tasks do |task| %>
    <%= render 'task_fields', :f => task %>
    <%= link_to_add_association 'Add task', f, :tasks, class: "links" %>
  <% end %>
  <div class="actions">
    <%= f.submit %>
<% end %>


Now here's my views / projects / _task_fields.html.erb file:

 <div id="nested-fields">
  <div class="field">
      <%= f.label :description %><br>
      <%= f.text_field :description %>

  <div class="field">
      <%= f.label :description %><br>
      <%= f.text_field :description %>
  <%= link_to_remove_association 'remove task', f %>


Isn't that exactly what the guide mentions? When I go to create a new project, it only shows the default name, name label, description text box, description text box, and "create project link". Here's the HTML output of the new project form:

<!DOCTYPE html>
  <link data-turbolinks-track="true" href="/assets/projects.css?body=1" media="all" rel="stylesheet" />
<link data-turbolinks-track="true" href="/assets/scaffolds.css?body=1" media="all" rel="stylesheet" />
<link data-turbolinks-track="true" href="/assets/application.css?body=1" media="all" rel="stylesheet" />
  <script data-turbolinks-track="true" src="/assets/jquery.js?body=1"></script>
<script data-turbolinks-track="true" src="/assets/jquery_ujs.js?body=1"></script>
<script data-turbolinks-track="true" src="/assets/turbolinks.js?body=1"></script>
<script data-turbolinks-track="true" src="/assets/projects.js?body=1"></script>
<script data-turbolinks-track="true" src="/assets/cocoon.js?body=1"></script>
<script data-turbolinks-track="true" src="/assets/application.js?body=1"></script>
  <meta content="authenticity_token" name="csrf-param" />
<meta content="uIpLnix47UNaBONCR+0SV/uz1uiulU6BHqKe5qENzHQ=" name="csrf-token" />

<h1>New project</h1>

<form accept-charset="UTF-8" action="/projects" class="new_project" id="new_project" method="post"><div style="display:none"><input name="utf8" type="hidden" value="&#x2713;" /><input name="authenticity_token" type="hidden" value="uIpLnix47UNaBONCR+0SV/uz1uiulU6BHqKe5qENzHQ=" /></div>

  <div class="field">
    <label for="project_name">Name</label><br>
    <input id="project_name" name="project[name]" type="text" />
  <div class="field">
    <label for="project_description">Description</label><br>
    <input id="project_description" name="project[description]" type="text" />
    <div class="actions">
    <input name="commit" type="submit" value="Create Project" />

<a href="/projects">Back</a>



Can someone please help me with this? It looks like I am doing everything as mentioned in the manual and I am getting nothing out of it.


source to share

1 answer


must be located outside the tag fields_for

, everything inside it will be replicated for every added task, and you usually want to add a link at the end, also nothing is displayed because no task is being created, in order to instantiate you either click link_to_add_association

or instantiate based on creating projects, this can be done when executing a project controller action by new


def new
    @project =


You can also create multiple tasks when creating a form by doing a loop like

3.times do




All Articles