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Dynamically add and remove nested has_many association fields in a Ruby on Rails form
Ruby CSS HTML CoffeeScript JavaScript

Nested Form Fields Build Status

This Rails gem helps creating forms for models with nested has_many associations.

It uses jQuery to dynamically add and remove nested associations.

  • Works for arbitrarily deeply nested associations (tested up to 4 levels).
  • Works with form builders like simple_form.
  • Requires Ruby 1.9 and the Rails asset pipeline


Add this line to your application's Gemfile:

gem 'nested_form_fields'

And then execute:

$ bundle

In your application.js file add:

//= require nested_form_fields


Assume you have a user model with nested videos:

class User < ActiveRecord::Base
  has_many :videos
  accepts_nested_attributes_for :videos, allow_destroy: true

Use the nested_fields_for helper inside your user form to add the video fields:

= form_for @user do |f|
  = f.nested_fields_for :videos do |ff|
    = ff.text_field :video_title

Links to add and remove fields can be added using the add_nested_fields_link and remove_nested_fields_link helpers:

= form_for @user do |f|
  = f.nested_fields_for :videos do |ff|
    = ff.remove_nested_fields_link
    = ff.text_field :video_title
  = f.add_nested_fields_link :videos

Note that remove_nested_fields_link needs to be called within the nested_fields_for call and add_nested_fields_link outside of it via the parent builder.

You can change the link text of remove_nested_fields_link and add_nested_fields_link like this:

  ff.remove_nested_fields_link 'Remove me'
f.add_nested_fields_link :videos, 'Add another funtastic video'

You can add classes/attributes to the remove_nested_fields_link and add_nested_fields_link like this:

  ff.remove_nested_fields_link 'Remove me', class: 'btn btn-danger', role: 'button'
f.add_nested_fields_link :videos, 'Add another funtastic video', class: 'btn btn-primary', role: 'button'

You can change the type of the element wrapping the nested fields using the wrapper_tag option:

= f.nested_fields_for :videos, wrapper_tag: :div do |ff|

The default wrapper element is a fieldset. To add legend element to the fieldset use:

= f.nested_fields_for :videos, legend: "Video" do |ff|

You can pass options like you would to the content_tag method by nesting them in a :wrapper_options hash:

= f.nested_fields_for :videos, wrapper_options: { class: 'row' } do |ff|

There are 4 javascipt events firing before and after addition/removal of the fields in the nested_form_fields namespace. Namely: fields_adding, fields_added, fields_removing, fields_removed.

The events fields_added and fields_removed are triggered on the element being added or removed. The events bubble up so you can listen for them on any parent element. This makes it easy to add listeners when you have multiple nested_form_fields on the same page.

CoffeeScript samples:

# Listen on an element
initializeSortable -> ($el)
  $el.on 'fields_added.nested_form_fields', -> (event, param)
    console.log # The added field
    console.log $(this)      # $el

# Listen on document
$(document).on "fields_added.nested_form_fields", (event,param) ->
    switch param.object_class
        when "video"
            console.log "Video object added"
            console.log "INFO: Fields were successfully added, callback not handled."


  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Added some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request


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