Rails 3: virtual attribute not being set

Question

I have the following User model with a artist_attributes virtual attribute:

class User < ActiveRecord::Base
  attr_accessor :artist_attributes
  attr_accessible :artist_attributes

  belongs_to :artist
  accepts_nested_attributes_for :artist, update_only: true
end

Here is the artist model:

class Artist < ActiveRecord::Base
  has_one :user
end

The problem is that the virtual attribute is not being set. For example, here my user controller:

class Members::UsersController < Members::BaseController
  def update
    current_user.artist_attributes = params[:user].delete(:artist_attributes)
    p current_user.artist_attributes # => nil
    # ...
  end
end

And here is the form that is submitted:

<%= simple_form_for current_user, url: members_profile_path do |f| %>
  <%= f.simple_fields_for :artist do |ff| %>
    <%# ... %>
  <% end %>

  <%= f.submit "Edit profile", class: "btn btn-primary", disable_with: "Editing profile..." %>
<% end %>

Why isn't the artist_attributes virtual attribute not being set? Is it because of the nested form?

Update

Here is the params hash after I submit the form:

Parameters: {
  "utf8"=>"✓",
  "authenticity_token"=>"XQI4y7x7CSjxUhdYvEv2bLEjitwCfXxeTBUU3+kYS4g=",
  "user"=> {
    "email"=>"youjiii@gmail.com",
    "forename"=>"You",
    "surname"=>"Jiii",
    "password"=>"[FILTERED]",
    "password_confirmation"=>"[FILTERED]",
    "artist_attributes" => {
      "bio"=>"NERVO is awesome!",
      "phone_number"=>"",
      "city"=>"",
      "country"=>"Afghanistan"
    }
  },
  "commit"=>"Edit profile"}

Answer 1

Try this:

Change

current_user.artist_attributes = params[:user].delete(:artist_attributes)

To

if current_user.update_attributes(params[:user])
  # happy result
end

Nested attributes should be handled automatically by Rails. If you need a custom setter, define artist_attributes= and you should be good. I believe Rails 4 will support hash values in Postgresql. Meannwhile look here for Rails 3: http://travisjeffery.com/b/2012/02/using-postgress-hstore-with-rails/

Edit

According to your comment, I wouldn't store it in a virtual attribute if the goal is simply to send it to your API.

# Controller
def update
  if User.update_artist(params[:user][:artist_attributes])
    # happy thoughts
  end
end

# User model
def update_artist(artist_attributes)
  begin
    # API call
  rescue api exception
    log a message like "Couldn't update at this moment"   
  end
end