Polymorphism and forms in Ruby on Rails - ruby-on-rails

Question

I've been full of questions lately, but thanks to this awesome community, I'm learning a ton.
I got all the help I needed with polymorphic associations earlier and now I have a question about tackling forms with polymorphic models. For instance I have Phoneable and User, so when I create my form to register a user, I want to be able to assign a few phone numbers to the user (ie: cell, work, home).
class User < ActiveRecord::Base
has_many :phones, :as => :phoneable
end
class Phone < ActiveRecord::Base
belongs_to :phoneable, :polymorphic => true
end
class CreateUsers < ActiveRecord::Migration
t.column :name, :string
t.references :phoneable, :polymorphic => true
end
class CreatePhones < ActiveRecord::Migration
t.column :area_code, :integer
t.column :number, :integer
t.column :type, :string
t.references :phoneable, :polymorphic => true
end
Now when I create my form, I'm getting confused. Normally I would do the following:
- form_for :user, :html => {:multipart => true} do |form|
%fieldset
%label{:for => "name"} Name:
= form.text_field :name
##now how do I go about adding a phone number?
##typically I'd do this:
##%label{:for => "phone"} Phone:
##= form.text_field :phone
Using polymorphism, would I just approach the same way, but use fields_for?
- user_form.fields_for :phone do |phone| %>
%label{for => "area_code"} Area Code:
= phone.text_field :area_code
%label{for => "number"} Number:
= phone.text_field :number
Is this the correct approach in this instance?

Answer 1

Before we go further, I did notice one issue - you do not need the t.references with the has_many side of the association. So you do not need it in the create_user model. What that does is it creates the phonable_id and the phoneable_type columns, you only need that in the polymorphic model.
You are heading down the correct path with the fields_for approach. But in order to get that working, you need to tell the model how to handle those fields. You do that with the accepts_nested_attributes_for class method.
class User < ActiveRecord::Base
has_many :phones, :as => :phoneable
accepts_nested_attributes_for :phones
end
and one minor thing, you will need to have the fields_for point to the exact name of the association
- form_for #user do |user_form|
- user_form.fields_for :phones do |phone|
Instead of
- form_for #user do |user_form|
- user_form.fields_for :phone do |phone|
and make sure you remove your stray %> erb tag :)
More on accepts_nested_attributes_for: http://api.rubyonrails.org/classes/ActiveRecord/NestedAttributes/ClassMethods.html
I hope this helps!