Rails 5.0 and JQuery .dialog() Not Working - jquery-ui

Question

I'm upgrading a rails app from 4.2 to 5.0. The ruby version is 2.6.4
The app has a view that allows the user to click a link to run a scheduling script that assigns students into courses/classes. The script can take several minutes to run to completion, so we show a modal dialog box that, like a progress-bar, shows where the process is currently at. But in the rails 5.0 version, this is not working. There is no error(s), just the popup is not appearing. I figured it was a JQuery thing, so using try/catch blocks, I found it is in the .dialog(...) call. But I'm not sure why it is failing. I believe I have the correct JQuery gems and the assets/files set up correctly for rails 5.0.
Gemfile:
source 'http://rubygems.org'
gem 'rails', '~> 5.0'
gem 'jquery-rails'
gem 'jquery-ui-rails'
...
Gemfile.lock:
...
jquery-rails (4.4.0)
rails-dom-testing (>= 1, < 3)
railties (>= 4.2.0)
thor (>= 0.14, < 2.0)
jquery-ui-rails (6.0.1)
railties (>= 3.2.16)
...
app/assets/application.js:
...
//= require jquery-ui
//= require jquery
//= require jquery_ujs
//= require jquery-ui/widgets/dialog
//= require_tree .
app/assets/stylesheets/application.css
...
*= require_self
*= require_tree .
*= require jquery-ui
*= require jquery-ui/dialog
The popup form:
app/views/elements/_scheduling_dialog_popup.html.erb:
<%
# This partial will attach a Jquery event to a submit button that will display a modal-screen
# during the (potentially) long scheduling process.
%>
<% content_for :head do %>
<script type="text/javascript">
jQuery(document).ready(function() {
jQuery("a#autoschedule").click(function() {
JQuery('div#import_modal_box').dialog({bgiframe: true, modal: true, width:450, draggable: false, closeOnEscape: false, resizable: false});
});
});
</script>
<% end %>
<div id="import_modal_box" style="display:none;">
<p style="float:left;margin-right:1em;"><%= image_tag 'ajax-loader.gif' %></p>
<h3>Auto Class Assignment for <%= pluralize(Student.count,'student') %></h3>
<p>There are <%= pluralize(ClassTime.sum(:enrollment_limit),'spot') %> available in <%= pluralize(ClassTime.count,'class') %> for <%= pluralize(UpcomingCourse.count,'course')%>.</p><p>This may take a few minutes, please wait.</p>
<p> </p>
</div>
I've read through the docs at: ruby-docs. I see I only need to use //= require jquery-ui to require everything , but I added the //= require jquery-ui/widgets/dialog just to be sure.
What am I missing to get this to work?
Thanks for any advise.

Answer 1

I was "finally" able to resolve this issue. It actually had nothing to do with the dialog() function, directly. I brought up the Developer Tools and ran the Console tab/window to see if I was getting any errors or warnings and found I had a ton of ReferenceError: jQuery is not defined .... errors. After some searching I found that Rails 5.2 does not need jquery_ujs, so I removed the //= require jquery_ujs line from my assets/javascripts/application.js file. Now it works.