Finding the Object in the Builder

my_model.rb

# my_value_array :text
class MyModel < AciveRecord::Base
  serialize :my_value_array, Array
end

view_before.html.erb

<%= form_for @my_model do |f| %>
  <%= f.text_field :my_value_array %>
  # produces <input type="text" id="my_model_my_value_array" name="my_model[my_value_array]" value="#{@my_model.my_value_array}" />
  <%= f.submit %>
<% end %>

view_cafter.html.erb

<%= form_for @my_model do |f| %>
  # existing values in the array
  <% if f.object.my_value_array.present? %>
    <% f.object.my_value_array.each do |v| %>
      <input type="text" id="my_model_my_value_array" name="my_model[my_value_array][]" value="#{v}" />
    <% end %>
  <% end %>
  # space for new values for the array
  <input type="text" id="my_model_my_value_array" name="my_model[my_value_array][]" />
  <input type="text" id="my_model_my_value_array" name="my_model[my_value_array][]" />
  # could be clever here to dynamically add these to allow adding more then 2 elements at a time
  <%= f.submit %>
<% end %>