Ruby on Rails, form helper with object method - ruby-on-rails

Question

I have a model with a method called date_string. The point of this method is to return a formatted date string when being used in a share view. Here is the view code.
<div class="field control-group">
<div class="control-label">
<%= f.label :business_hour , :date_string %>
</div>
I am expecting the f.label call to function like in this api doc, with :business_hour being the object, and :date_string being the method. However, the only thing that is rendered to the view is the string 'Date string' or 'date_string'.
Any help on getting a view class to call a method, not a property, on a model is greatly appreciated.
Business_Hour code
class BusinessHour < ActiveRecord::Base
attr_accessible :business_hourable_id,
:business_hourable_type,
:close_time, :day, :open_time,
:order , :business_date
belongs_to :business_hourable , :polymorphic => true
def date_string()
if business_date.nil?
return ''
else
return_string = business_date.strftime( '%a %b\ %e , %Y' )
end
end
end
Here is the full partial code(shared/business_hours):
<div class="field control-group">
<div class="control-label funkiness">
<%= F.label :business_hour , :date_string %>
</div>
<div class="controls">
<%= f.select :open_time, available_hours, :include_blank => true %>
</div>
<div class="control-label">
<%= f.label :open_time, 'Close Time' %>
</div>
<div class="controls">
<%= f.select :close_time, available_hours, :include_blank => true %>
</div>
</div>
Here is the pertinent part of the _form
<%= form_for (#some_show), html: {class: "form-horizontal pull-left"} do |f| %>
...
<%= f.fields_for :business_hours do |operating_time| %>
<%= render :partial => 'shared/business_hours',
:locals => {:f => operating_time} %>
<% end %>
And finally, here is the edit action of the controller
# GET /some_shows/1/edit
def edit
#some_show = SomeShow.find(params[:id])
end

Answer 1

So the solution that worked for me was to take the date_string off of my model, and implement it in a helper. Then, I modified my partial view so it looks like this:
<div class='field control-group hour_dropdown_2'>
<div class='field control-group'>
<div class="control-label">
<label><%= get_business_hour_string(f) %></label>
</div>
<h4 class='no-break-h'>From</h4>
<%= select :open_time, available_hours, :include_blank => false %>
<h4 class='no-break-h'>To</h4>
<%= select :close_time, available_hours, :include_blank => false %>
</div>
</div>
My select tags are still busted and I don't know why for my _address partial I get an f.whatever, but for the BusinessHour partial I get nothing in the way of form helpers.