This is version 9.1 of lab_app.py. It adds support for remote Arduino node IDs.

lab_app.py

'''
FILE NAME
lab_app.py
Version 11

1. WHAT IT DOES
This version adds support for node IDs

2. REQUIRES
* Any Raspberry Pi

3. ORIGINAL WORK
Raspberry Full Stack 2020, Peter Dalmaris

4. HARDWARE
* Any Raspberry Pi
* DHT11 or 22
* 10KOhm resistor
* An nRF24 transceiver module
* A 220uF bypass capacitor
* Breadboard
* Wires

5. SOFTWARE
Command line terminal
Simple text editor
Libraries:
from flask import Flask, request, render_template, sqlite3

6. WARNING!
None

7. CREATED

8. TYPICAL OUTPUT
A simple web page served by this flask application in the user's browser.
The page contains the current temperature and humidity.
A second page that displays historical environment data from the SQLite3 database.
The historical records can be selected by specifying a date range in the request URL.
The user can now click on one of the date/time buttons to quickly select one of the available record ranges.
The user can use Jquery widgets to select a date/time range.
The user can explore historical data to Plotly for visualisation and processing.

 // 9. COMMENTS
--
 // 10. END
'''

from flask import Flask, request, render_template
import time
import datetime
import arrow
import sqlite3
import sys
import Adafruit_DHT
import plotly.plotly as py
from plotly.graph_objs import *

app         = Flask(__name__)
app.debug   = True # Make this False if you are no longer debugging

@app.route("/")
def hello():
    return "Hello World! rpi4. </br></br>Get <a href='/lab_temp'> current sensor readings</a> on the Raspberry Pi."

@app.route("/lab_temp")
def lab_temp():
	#import sys
	#import Adafruit_DHT
	humidity, temperature = Adafruit_DHT.read_retry(Adafruit_DHT.AM2302, 17)
	if humidity is not None and temperature is not None:
		return render_template("lab_temp.html",temp=temperature,hum=humidity)
	else:
		return render_template("no_sensor.html")

@app.route("/lab_env_db", methods=['GET'])  #Add date limits in the URL #Arguments: from=2015-03-04&to=2015-03-05
def lab_env_db():
	temperatures, humidities, timezone, from_date_str, to_date_str, sensor_id = get_records()

	# Create new record tables so that datetimes are adjusted back to the user browser's time zone.
	time_adjusted_temperatures = []
	time_adjusted_humidities   = []
	for record in temperatures:
            local_timedate = arrow.get(record[0], "YYYY-MM-DD HH:mm:ss").to(timezone)
            time_adjusted_temperatures.append([local_timedate.format('YYYY-MM-DD HH:mm:ss'), round(record[2],2)])

	for record in humidities:
            local_timedate = arrow.get(record[0], "YYYY-MM-DD HH:mm:ss").to(timezone)
            time_adjusted_humidities.append([local_timedate.format('YYYY-MM-DD HH:mm:ss'), round(record[2],2)])

	print("rendering lab_env_db.html with: %s, %s, %s, sensor_id %s" % (timezone, from_date_str, to_date_str, sensor_id))

	return render_template("lab_env_db.html",	timezone		= timezone,
							temp 			= time_adjusted_temperatures,
							hum 			= time_adjusted_humidities,
							from_date 		= from_date_str,
							to_date 		= to_date_str,
							temp_items 		= len(temperatures),
							query_string	        = request.query_string, #This query string is used
							        					#by the Plotly link
							hum_items 		= len(humidities),
                            sensorid                = sensor_id)

def get_records():
    from_date_str 	= request.args.get('from',time.strftime("%Y-%m-%d 00:00")) #Get the from date value from the URL, or use the start of day today UTC
    to_date_str 	= request.args.get('to',time.strftime("%Y-%m-%d %H:%M"))   #Get the to date value from the URL, or use now UTC
    timezone 	    = request.args.get('timezone','Etc/UTC')                      #Get the timezone, or use UTC
    range_h_form	= request.args.get('range_h','')                              #This will return a string, if field range_h exists in the request
    range_h_int 	= "nan"  #initialise this variable with not a number
    sensor_id       = request.args.get('sensor_id','1')                           #Get the sensor ID, or fall back to 1

    print ("REQUEST:")
    print (request.args)

    try:
        range_h_int     = int(range_h_form)
    except:
        print ("range_h_form not a number")

    print ("Received from browser: From: %s, To: %s, Timezon: %s, Range: %s, Sensor_id: %s" % (from_date_str, to_date_str, timezone, range_h_int, sensor_id))

    if not validate_date(from_date_str):			# Validate date before sending it to the DB
        from_date_str 	= time.strftime("%Y-%m-%d 00:00")
    if not validate_date(to_date_str):
        to_date_str 	= time.strftime("%Y-%m-%d %H:%M")		# Validate date before sending it to the DB

    print ("Time adjusted: From: %s, To: %s, Timezon: %s, Range: %s, Sensor_id: %s" % (from_date_str, to_date_str, timezone, range_h_int, sensor_id))

    # Create datetime object so that we can convert to UTC from the browser's local time
    from_date_obj       = datetime.datetime.strptime(from_date_str,'%Y-%m-%d %H:%M')
    to_date_obj         = datetime.datetime.strptime(to_date_str,'%Y-%m-%d %H:%M')

    # If range_h is defined, we don't need the from and to times
    if isinstance(range_h_int,int):
        arrow_time_from = arrow.utcnow().shift(hours=-range_h_int)
        arrow_time_to   = arrow.utcnow()
        from_date_utc   = arrow_time_from.strftime("%Y-%m-%d %H:%M")
        to_date_utc     = arrow_time_to.strftime("%Y-%m-%d %H:%M")
        from_date_str   = arrow_time_from.to(timezone).strftime("%Y-%m-%d %H:%M")
        to_date_str	= arrow_time_to.to(timezone).strftime("%Y-%m-%d %H:%M")
    else:
	#Convert datetimes to UTC so we can retrieve the appropriate records from the database
        from_date_utc   = arrow.get(from_date_obj, timezone).to('Etc/UTC').strftime("%Y-%m-%d %H:%M")
        to_date_utc     = arrow.get(to_date_obj, timezone).to('Etc/UTC').strftime("%Y-%m-%d %H:%M")

    print("From UTC: ", from_date_utc)
    print("To UTC: ", to_date_utc)
    print("From: ", from_date_str)
    print("To: ", to_date_str)

    conn 			    = sqlite3.connect('/var/www/lab_app/lab_app.db')
    curs 			    = conn.cursor()
	
    temp_sql = "SELECT * FROM temperatures WHERE (rDateTime BETWEEN '%s' AND '%s') AND sensorID = %s" % (from_date_utc.format('YYY-MM-DD HH:mm'), to_date_utc.format('YYY-MM-DD HH:mm'), sensor_id)
    print(temp_sql)
    curs.execute(temp_sql)
    temperatures 	    = curs.fetchall()

    hum_sql = "SELECT * FROM humidities WHERE sensorID = %s AND (rDateTime BETWEEN '%s' AND '%s')" % (sensor_id, from_date_utc.format('YYYY-MM-DD HH:mm'), to_date_utc.format('YYYY-MM-DD HH:mm'))
    curs.execute(hum_sql)
    humidities 		    = curs.fetchall()
    print(temperatures)
    conn.close()

    return [temperatures, humidities, timezone, from_date_str, to_date_str, sensor_id]


@app.route("/to_plotly", methods=['GET'])  #This method will send the data to ploty.
def to_plotly():
	#import plotly.plotly as py
	#from plotly.graph_objs import *

	temperatures, humidities, timezone, from_date_str, to_date_str, sensor_id = get_records()

	# Create new record tables so that datetimes are adjusted back to the user browser's time zone.
	time_series_adjusted_tempreratures  = []
	time_series_adjusted_humidities     = []
	time_series_temprerature_values     = []
	time_series_humidity_values 	    = []

	for record in temperatures:
            local_timedate = arrow.get(record[0], "YYYY-MM-DD HH:mm:ss").to(timezone)
            time_series_adjusted_tempreratures.append(local_timedate.format('YYYY-MM-DD HH:mm:ss'))
            time_series_temprerature_values.append(round(record[2],2))

	for record in humidities:
            local_timedate = arrow.get(record[0], "YYYY-MM-DD HH:mm:ss").to(timezone)
            time_series_adjusted_humidities.append(local_timedate.format('YYYY-MM-DD HH:mm:ss'))   #Best to pass datetime in text
												    #so that Plotly respects it
            time_series_humidity_values.append(round(record[2],2))

	temp = Scatter(
        		x=time_series_adjusted_tempreratures,
        		y=time_series_temprerature_values,
        		name='Temperature'
    				)
	hum = Scatter(
        		x=time_series_adjusted_humidities,
        		y=time_series_humidity_values,
        		name='Humidity',
        		yaxis='y2'
    				)

	data = Data([temp, hum])

	layout = Layout(    title="Temperature and humidity in Peter's lab",
				    xaxis=XAxis(
				        type='date',
				        autorange=True
				    ),
				    yaxis=YAxis(
				    	title='Celcius',
				        type='linear',
				        autorange=True
				    ),
				    yaxis2=YAxis(
				    	title='Percent',
				        type='linear',
				        autorange=True,
				        overlaying='y',
				        side='right'
				    )

					)
	fig = Figure(data=data, layout=layout)
	plot_url = py.plot(fig, filename='lab_temp_hum')

	return plot_url


def validate_date(d):
    try:
        datetime.datetime.strptime(d, '%Y-%m-%d %H:%M')
        return True
    except ValueError:
        return False

if __name__ == "__main__":
    app.run(host='0.0.0.0', port=8080)