Arctic Kiwi - Experts in Web Development, Application Development, and Web Design

After several hours beating my head against a desk trying to get my nested Formtastic form working, I figured out the reason.

Assuming you have a simple Rails one-to-many relationship:

class Candidate < ActiveRecord::Base
  has_many :jobs
end

class Job < ActiveRecord::Base
  belongs_to :candidate
end

and you have a form which can update our candidate and up to 3 jobs at the same time, so we prepare that in our controller:

class CandidatesController < ApplicationController
  def new
    @candidate = Candidate.new
    3.times do
      @candidate.jobs.build
    end
  end
end

so the form allows creation of the candidate and 3 jobs too:

<% semantic_form_for @candidate do |f| %>
  <%= f.inputs %>
  <%= f.inputs :for => :jobs do |j| %>
    <%= j.input :name %>
  <% end %>
<% end %>

but for some reason this just didn’t work.

The jobs input displayed only once and j.object was nil.

After some searching and head scratching I finally figured this out, which isn’t mentioned on the Formtastic site. You need to use accepts_nested_attributes_for.

So the model will look like this:

class Candidate < ActiveRecord::Base
  has_many :jobs
  accepts_nested_attributes_for :jobs
end

class Job < ActiveRecord::Base
  belongs_to :candidate
end

And then it works!