Getting Flask to alter selected value in HTML drop down

Question

I'm writing a prototype front end for a home heating control system and when the user selects the room and day of the week from the drop down box, I want to be able to query the Redis database and retrieve the currently set temperatures for each hour and use this to set the selected value in the temperature drop down boxes. The user can then change a value or values and submit them. I have the submit and write working, just trying to get my head around setting the selected.

Here's the HTML:

{% extends "bootstrap/base.html" %}
{% block title %}Setting Room Temperatures{% endblock %}
{% block navbar %}

  

{% endblock %}
{% block content %}


Room temperature configuration
 

Room:







Day  :






 
 1AM :
 
2AM :














{% endblock %}

And here's the Python Flask code

from flask import Flask
from flask import request
from flask import render_template
from flask_bootstrap import Bootstrap
import redis

app = Flask(__name__)
app.debug = True
bootstrap = Bootstrap(app)

db = redis.Redis('localhost')

@app.route('/', methods=['GET','POST'])
def heating_config_form():
    error=""
    if request.method == 'POST' and request.form['update'] == 'submitted':
        Room = (request.form.get('roomselect'))
        Day = (request.form.get('dayselect'))
        AM1 = (request.form.get('1AM'))
        AM2 = (request.form.get('2AM'))
        key = (Room + "_" + Day)
        db.hset(key, "1:00", AM1)
        db.hset(key, "2:00", AM2)
        return render_template('set-room-tempv5.html')
    else :
        return render_template('set-room-tempv5.html')
if __name__ == '__main__':
    app.run(host='0.0.0.0', debug=True)

I'm aware there are probably better ways of approaching this (WTForms?) but wanted to get a simple setting interface that I understand so I can prototype the system while developing a better front end, as I'm new to Flask and don't want the whole heating system to be dependent on my ability to pick this up :)

Adding the temperature to the database works fine, this is a typical monitor output from the redis-cli monitor

127.0.0.1:6379> monitor
OK
1482336847.287342 [0 127.0.0.1:34180] "HSET" "kitchen_tuesday" "1:00" "5"
1482336847.288042 [0 127.0.0.1:34180] "HSET" "kitchen_tuesday" "2:00" "5"

I was thinking that maybe something like the following context processor could help?

@app.context_processor
def utility_processor():
    def retrieve_temp(sroom, sday, stime):
        skey= (sroom + "_" + sday)
        stemp = db.hget(skey, stime)
        return stemp
    return dict(retrieve_temp=retrieve_temp)

which would make the function retrieve_temp available to all templates - I think!

Then somehow, once the template is rendered, the default room and day is used to set the "selected" option on the time drop downs, and then every time the room and day drop downs are moved, the same happens again.

So if the default is dining and Monday given they are the first in the select options, the temperatures for 1AM and 2AM are retrieved and set as selected for these drop downs (there are more times and more temps, these have been deleted for brevity). If the room and/or the day is changed, it happens again.

Getting Flask to alter selected value in HTML drop down

Answers (1)

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