Help with embedding Bokeh app in Tornado server with custom HTML template

Hi all,

I need assistance with including a custom HTML template in the following example app which is embedded in a Tornado server. I am trying to insert a line of javascript to prompt the user if he/she navigates away from the page.

When I had a prefix to the URL in the following line of code in

server.io_loop.add_callback(view, "http://localhost:5006/SatProd)

My custom template does not load which contains the javascript code to cause a dialog prompt. If I leave the prefix off and only use “http://localhost:5006/”, then my custom template is loaded correctly.

The app structure is as follows:

  • Boke_test_app

    • SatProd

      • templates

        • index.html



from jinja2 import Environment, FileSystemLoader
from tornado.web import RequestHandler
from bokeh.embed import server_document
from bokeh.server.server import Server
import SatProd.main

env = Environment(loader=FileSystemLoader('./SatProd/templates'))

class IndexHandler(RequestHandler):
    def get(self):
        template = env.get_template('index.html')
        script = server_document('http://localhost:5006/SatProd')
        self.write(template.render(script=script, template="Tornado"))

# Setting num_procs here means we can't touch the IOLoop before now, we must
# let Server handle that. If you need to explicitly handle IOLoops then you
# will need to use the lower level BaseServer class.
# The `static/` end point is reserved for Bokeh resources, as specified in
# bokeh.server.urls. In order to make your own end point for static resources,
# add the following to the `extra_patterns` argument, replacing `DIR` with the desired directory.
# (r'/DIR/(.*)', StaticFileHandler, {'path': os.path.normpath(os.path.dirname(__file__) + '/DIR')})
server = Server({'/SatProd': SatProd.main.bkapp}, num_procs=1, extra_patterns=[('/', IndexHandler)])

if __name__ == '__main__':
    from bokeh.util.browser import view

    print('Opening Tornado app with embedded Bokeh application on http://localhost:5006/')

    server.io_loop.add_callback(view, "http://localhost:5006/")
    #server.io_loop.add_callback(view, "http://localhost:5006/SatProd")

from bokeh.layouts import column
from bokeh.models import ColumnDataSource, Slider
from bokeh.plotting import figure
from bokeh.sampledata.sea_surface_temperature import sea_surface_temperature
import panel as pn

def bkapp(doc):
    df = sea_surface_temperature.copy()
    source = ColumnDataSource(data=df)

    plot = figure(x_axis_type='datetime', y_range=(0, 25), y_axis_label='Temperature (Celsius)',
                  title="Sea Surface Temperature at 43.18, -70.43")
    plot.line('time', 'temperature', source=source)

    def callback(attr, old, new):
        if new == 0:
            data = df
            data = df.rolling(f"{new}D").mean() = ColumnDataSource.from_df(data)

    slider = Slider(start=0, end=30, value=0, step=1, title="Smoothing by N Days")
    slider.on_change('value', callback)

    _col = pn.pane.Bokeh(column(slider, plot))
    #doc.add_root(column(slider, plot))
    _col.server_doc(doc=doc, title='SatProd Tool')

    #doc.theme = Theme(filename="theme.yaml")
if __name__ == "__main__":


<!DOCTYPE html>
<html lang="en">
{% block head %}
    {% block inner_head %}
    <meta charset="utf-8">
    <title>{% block title %}{{ title | e if title else "Bokeh Plot" }}{% endblock %}</title>
    <script> window.onbeforeunload = function() {return ""};</script>
    {% block preamble %}{% endblock %}
    {% block resources %}
        {% block css_resources %}
        {{ bokeh_css | indent(8) if bokeh_css }}
        {% endblock %}
        {% block js_resources %}
        {{ bokeh_js | indent(8) if bokeh_js }}
        {% endblock %}
    {% endblock %}
    {% block postamble %}{% endblock %}
    {% endblock %}
{% endblock %}
{% block body %}
    {% block inner_body %}
    {% block contents %}
        {% for doc in docs %}
        {{ embed(doc) if doc.elementid }}
        {% for root in doc.roots %}
            {{ embed(root) | indent(10) }}
        {% endfor %}
        {% endfor %}
    {% endblock %}
    {{ script | indent(8) }}
    {% endblock %}
{% endblock %}

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