RondoForm

Handle dynamic nested forms, same as Cocoon, but using StimulusJS

Installation

Install the gem and add to the application's Gemfile by executing:

$ bundle add rondo_form

Or inside the Gemfile add the following

$ gem 'rondo_form', '~> 0.2.5'

Run the installation task:

$ rails g rondo_form:install 

Usage

For example, you have Project model, which has has_many relationship with Task model:

rails g scaffold Project name:string description:string
rails g model Task description:string done:boolean project:belongs_to

You need to add accepts_nested_attributes_for to Project model:

class Project < ApplicationRecord
  has_many :tasks, dependent: :destroy
  accepts_nested_attributes_for :tasks, reject_if: :all_blank, allow_destroy: true
end

Sample with SimpleForm

The RondoForm gem adds two helper functions: link_to_add_association and link_to_remove_association.
The example below illustrates the way to use it.

In your projects/_form partial:

<%= simple_form_for(@project) do |f| %>

  <div class="form-inputs">
    <%= f.input :name %>
    <%= f.input :description %>
  </div>

  <h3 class="text-xl mt-4">Tasks</h3>
  <div class="my-2" data-controller="nested-rondo" data-nested-rondo-field-class-value="task-field">
    <div data-nested-rondo-target="fieldContain">
      <%= f.simple_fields_for :tasks do |task| %>
        <%= render "task_fields", f: task %>
      <% end %>
    </div>
    <div class="links">
      <%= link_to_add_association "Add Task", f, :tasks %>
    </div>
  </div>

  <div class="form-actions mt-4">
    <%= f.button :submit %>
  </div>
<% end %>

In your _task_fields partial:

<div class="task-field">
  <%= f.input :description %>
  <%= f.input :done, as: :boolean %>
  <%= link_to_remove_association "Remove Task", f %>
</div>

Convention:

• For convention, I named Stimulus controller nested-rondo. But you can change the name of Javascript file and the value of data-controller to match your purpose.
• data-nested-rondo-target="fieldContain" must be added to an element that wraps all nested fields, the new field will be appended to this element.
• data-nested-rondo-field-class-value is used to detect the element that needs to be removed. Its value must match the class name of an element that wraps the partial. If you do not declare it, it will default remove the closest parent element.

View details implement for this sample at rondo_form_demo_turbo_8

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/hungle00/rondo_form.

License

The gem is available as open source under the terms of the MIT License.