.row
  .col-md-6
    = semantic_form_for(:user, url: roles_admin_conference_path(@conference.short_title), remote: true) do |f|
      %h4
        = f.input :roles, collection: @roles, label: 'Show users for role: '

= render partial: 'roles'

:javascript

  $("#user_roles_input").change(function () {

    var url = document.forms[0].action;
    var selected_role = $(this).find('option:selected').attr('value');

    $.ajax({
      url: url,
      type: "POST",
      data: {user: { roles: selected_role } },
      dataType: "script"
    });
  });