twitter bootstrap popup modals with Rails JS ERB (ActiveRecord Model)

_create.html.erb

<% html = render partial: 'partial_to_render',
                 locals: { my_model: my_model } %>
$.unblockUI();
$('.modal').modal('hide');
$('#my-element').html('<%=j html %>');
$.jGrowl('<%= t(message) %>', { theme: 'alert-success' });

_new.html.erb

<div class="modal fade"
     id="modal"
     tabindex="-1"
     role="dialog"
     aria-labelledby="modal_label"
     aria-hidden="true">
  <div class="modal-dialog modal-lg">
    <div class="modal-content">
      <%= simple_form_for(my_model,
                          defaults: {
                            label_html: { class: 'col-sm-4' },
                            input_wrapper_html: { class: 'col-sm-4' }
                          },
                          html: {
                            class: 'form-horizontal block',
                            remote: true,
                            role: 'form'
                          },
                          wrapper: :horizontal_form) do |form| %>
      <div class="modal-header">
        <button type="button"
                class="close"
                data-dismiss="modal"
                aria-hidden="true">
        &times;
        </button>
        <h4 class="modal-title">
          <%= t('.title') %>
        </h4>
      </div>
      <div class="modal-body">
        <%= error_messages(my_model) %>
        <%= form.input :my_field %>
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-default" data-dismiss="modal">
          <%= t('links.cancel') %>
        </button>
        <input type="submit" class="btn btn-primary"
               value="<%= t('links.save') %>" />
      </div>
      <% end %>
    </div>
  </div>
</div>

_new.js.erb

var $element = $('<%=j render partial: 'new', \
                              locals: { my_model: my_model } %>');

if ($('#modal').length == 0) {
  $('body').append($element);
  $element
    .modal()
    .on('shown.bs.modal', function () {
      setupModal();
      $('.modal input[type=text][name]:first').focus()
    })
    .on('hidden.bs.modal', function () { $(this).remove(); });
} else {
  $('.modal-body').replaceWith($element.find('.modal-body'));

  setupModal();
}

function setupModal() {
  $.unblockUI();
}

my_models_controller.rb

class MyModelsController < ApplicationController
  respond_to :js

  def create
    render_new and return unless my_model.valid?

    if my_model.save
      render :create,
             locals: { message: '.success' }
    else
      render_new
    end
  end
  
  def render_new
    render :new, locals: { my_model: my_model }
  end
  
  def my_model
    @my_model ||= MyModel.new(my_params)
  end
  
  def my_params
    return {} unless params[:my_model]
    
    params.require(:my_model).permit(:my_field)
  end
end

view.html.erb

<%= link_to t('links.new_label'),
              new_model_path,
              class: 'btn btn-link block',
              remote: true %>