Forms to create and update Mongoid array fields

I've been struggling to create a form for a Mongoid model that has an array field. I want my form to have on text box per entry in the array. If I'm creating a new record, the default will be one empty field (and some javascript to add new fields dynamically on the page).

I've searched around for a solution using fields_for but it seems that is more intended to handle the case where you have an array of objects/models and not the case I have, which is an array of strings.

I'm going to use the example of a person and a phone number.

class Person
  include Mongoid::Document
  field :name, :type => String
  field :phone_numbers, :type => Array
end

For the controller, just assume the typical controller but in the new method I initialized the phone_number array with one blank string.

Here's the form code:

  <%= form_for(@person) do |f| %>
    <div class="field">
      <%= f.label :name %><br />
      <%= f.text_field :name %>
    </div>
    <div class="field">
      <%= f.label :phone_numbers %><br />
      <% @person.phone_numbers.each do |phone_number| %>
        <%= text_field_tag "person[phone_numbers][]", phone_number %>
      <% end %>
    </div>
  <% end %>

This all works fine. There are a few things that I don't like.

• The hardcoded name of the field in the text_field_tag call.
• Using text_field_tag instead of f.text_field
• Having the feeling like I should somehow be using fields_for instead of this

Does anybody have any better suggestions on how to implement this? Or would you consider this correct?