Grouped Select Example

grouped_select.coffee

# :coffeescript
jQuery ->
  designs = $('.design').html()
  $('.style').change ->
    style = $('.style option:selected').text()
    options = $(designs).filter("optgroup[label='" + style + "']").html()
    $('.design').html(options)

grouped_select.haml

-# scopes the designs based on the style choice. using simple_form grouped_select

.row
  .col-md-3
    = f.input :style_id, collection: Style.glazed_panels.options_for_select, input_html: {class: 'form-control style'}, include_blank: false
.row
  .col-md-3
    .form-group
      -# = f.input(:design_id, collection: RenaissanceDesign.options_for_select, input_html: {class: 'form-control design'}, include_blank: false )
      = f.input :design_id, collection: Style.glazed_panels, as: :grouped_select, group_method: :designs, input_html: {class: 'form-control design'}

models.rb

# Models and associations.
class RenaissanceDesign < ActiveRecord::Base
  belongs_to :style
end

class Style < ActiveRecord::Base
  has_many :designs, class_name: 'RenaissanceDesign'
  scope :glazed_panels, -> { where('......') }
  scope :options_for_select, -> {order(:name).pluck(:name, :id)}
end