Dynamic changes in rails form (simpleform) - ruby-on-rails

Question

I'm trying to make a simple form with this general structure:
o accept o decline
[submit]
when the radio button accept is checked and submit pressed, I want it to change the state of my model (called Offer here).
BUT when the button decline is checked, the form needs to change to something like this:
o accept x decline
Please enter reason here: [text box]
[submit]
Having entered a (mandatory) reason for declining and pressing submit, will change the state of the model Offer too, but differently.
I'm currently having problems getting the form to display the way I want. I'm using SimpleForm and tried something like this:
<%= simple_form_for #offer do |f| %>
<%= f.input accepts, as: :radio_buttons %>
<%= f.input :r_comment, as: :text, :label => 'Please enter reason here:' , :input_html => { :rows => 2, } %>
<%= f.button :submit %>
<% end %>
This of course doesn't work, because there is no "accepts" method or variable defined for offers (and it shouldn't be!). As for dynamically showing the input text box, I don't even have the slightest clue.
I'd be glad for any help you might offer,
Lordylike
UPDATE: HTML generated by simple_form
<div class="control-group radio_buttons optional">
<label class="radio_buttons optional control-label">Accept?</label>
<div class="controls">
<label class="radio">
<input class="radio_buttons optional" id="offer_accepts_decline" name="offer[accepts]" type="radio" value="Decline" />
Decline
</label>
<label class="radio">
<input class="radio_buttons optional" id="offer_accepts_accept" name="offer[accepts]" type="radio" value="Accept" />
Accept
</label>
</div>
UPDATE: HTML generated for comment box
<div class="control-group text optional">
<label class="text optional control-label" for="offer_r_comment">Reason for rejection:</label>
<div class="controls">
<textarea class="text optional" cols="40" id="offer_r_comment" name="offer[r_comment]" rows="2">
</textarea>
</div>
</div>

Answer 1

i'm not a fan of formtastic or simple_form but looking at the documentation, you should be able to do the following
# offer.rb
attr_accessor :accepts
# view
<%= f.input :accepts, as: :radio_buttons, collection: ['Decline', 'Accept'] %>
# js which can be placed inline or in the assets. let's use coffee
# you should also limit the selector below to include the class or the id of the
# radio buttons. I'm also not familiar with the html generated by simple form so
# the selectors to show and hide should also be changed.
$ ->
$(':radio').change ->
if $(this).prop('checked')
if $(this).val() == 'Accept'
$('#offer_r_comment').show()
else
$('#offer_r_comment').hide()
UPDATE: non coffee version. you can place this inside a script tag and just throw in the view.
$(document).ready(function() {
$(':radio').change(function() {
if ($(this).prop('checked'))
if ($(this).val() == 'Accept')
$('#offer_r_comment').show();
else
$('#offer_r_comment').hide();
});
});