I’m relatively new to using both bokeh and flask and am having some issues with data being shared between instances of my app.
I have removed a lot of my code so that I can include it below:
import datetime as dt
import threading
from os import getenv
import boto3
from awswrangler.timestream import query
from bokeh.application import Application
from bokeh.application.handlers.function import FunctionHandler
from bokeh.client.session import pull_session
from bokeh.embed import server_session
from bokeh.models import ColumnDataSource
from bokeh.plotting import figure
from bokeh.server.server import Server
from bokeh.util.token import generate_session_id
from dotenv import load_dotenv
from tornado.ioloop import IOLoop
from flask import Flask, render_template, request, jsonify
class DataViewer:
def make_doc(self, doc):
self.df = None
self.source = ColumnDataSource(data={"x": [], "y": []}, name="source")
self.p = figure(
name="p",
title="Level",
sizing_mode="stretch_width",
height=500,
x_axis_type="datetime",
y_range=(0, 1),
output_backend="webgl",
)
self.renderer = self.p.line(x="x", y="y", source=self.source, color="navy")
self.layout = self.p
doc.add_root(self.layout)
self.doc = doc
return self.doc
def prepare_view(self):
self.source.data = dict(
x=list(viewer.df["time"].apply(
lambda x: x.replace(tzinfo=dt.timezone.utc).timestamp() * 1000)
),
y=list(viewer.df["measure_value::double"]),
)
self.p.x_range.start = self.source.data['x'][0]
self.p.x_range.end = self.source.data['x'][-1]
self.p.y_range.start = max(self.source.data['y']) * 1.09
self.p.y_range.end = min(self.source.data['y']) * 1.09
def start_server(self, port=5000):
bokeh_app = Application(FunctionHandler(self.make_doc))
server = Server(
{"/bkapp": bokeh_app},
port=port,
io_loop=IOLoop(),
allow_websocket_origin=["*"],
)
server.start()
server.io_loop.start()
load_dotenv()
boto3.setup_default_session(profile_name=getenv("PROFILE"))
app = Flask(__name__)
@app.route("/")
def dataviewer():
with pull_session(
session_id=generate_session_id(), url=f"http://localhost:5006/bkapp"
) as session:
script = server_session(
session_id=session.id, url=f"http://localhost:5006/bkapp"
)
return render_template("base.html", script=script)
@app.route("/search", methods=["POST"])
def search():
print(request.form["imei"])
try:
viewer.df = query(
f"""
SELECT time, measure_value::double FROM DeviceData."RawData"
WHERE measure_name = 'WaterDepth' AND Imei = '{request.form['imei']}'
ORDER BY 1 ASC
"""
)
except Exception as e:
print("get_data error", e)
return (
"error getting data",
500,
)
if len(viewer.df) == 0:
print("No data found")
viewer.doc.add_next_tick_callback(viewer.prepare_view)
return jsonify(viewer.source.data)
def bk_worker():
global viewer
viewer = DataViewer()
viewer.start_server(port=5006)
threading.Thread(target=bk_worker).start()
app.run(port=5000)
And here is the html:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Data Viewer</title>
<script type="text/javascript" src="https://cdn.jsdelivr.net/jquery/latest/jquery.min.js"></script>
</head>
<body>
<section class="hero is-primary is-fullheight">
<div class="hero-body">
<div class="container has-text-centered">
<div id="loading-spinner" class="spinner-container">
<div class="spinner"></div>
</div>
<div class="flex-container">
<div class="left">
<form id="search">
<input name="imei" placeholder="IMEI" autofocus=""
pattern="^35(920610|710485|699584|612932|593998|308109|224763|019568)d{7}"> </input>
<button type="submit">Search</button>
</form>
</div>
</div>
{{ script|safe }}
<script>
$(document).ready(function () {
imei = 0;
$('#search').submit(function (e) {
e.preventDefault();
if (imei == $('#search input[name="imei"]').val()) {
return;
}
$("#loading-spinner").show();
imei = $('#search input[name="imei"]').val();
$.ajax({
url: 'search',
method: 'POST',
data: {
imei: imei
}
}).done(function (response) {
let ds = Bokeh.documents[0].get_model_by_name('source');
ds.data['x'] = response['x']; ds.data['y'] = response['y'];
ds.change.emit();
$("#loading-spinner").hide();
})
});
});
</script>
</div>
</div>
</section>
</body>
</html>
I am using bokeh as a visualiser for an aws timestream database. I originally used the built in widgets but found they did not have as much flexibilty as I needed. This led me to just use html with ajax and direct my requests to flask which would then run the function which would’ve been a callback for a bokeh button.
My issue is that if I have two instances on this app on different tabs they are somehow linked. When making a search from each instance in quick succession, only one instance will update correctly. It seems like the instance that does not work correctly does get some data but the one that does update gets the set of data for each search. Here is a video demonstrating this:
https://youtu.be/DdgF0fi8CLY
I was also having a similar issue with callbacks that I had written which I have omitted from the code above as I believe the underlying issue has nothing to do with them.
I have tried looking at ways to separate instances, namely pull_session and using session ids but I just can’t seem to get this to work.
Any help would be greatly appreciated