How to update variable within a while loop?

Question

I update the variable directly in the database (manually). But, the code in the while loop never updates the variable because it is in a loop, I would like to know what I should do to get the new value.

Maybe exit the loop and reopen it? I tried with break, but it closes the script.

import sqlite3

def read_data(data, table):
    con = sqlite3.connect("settings.db")
    cur = con.cursor()
    read_data.row = cur.execute(f"SELECT {data} FROM {table}").fetchall()[0][0]

read_data("data", "eyes")
eyes = read_data.row

while True:
    read_data("data", "eyes")
    eyes_loop = read_data.row

    if eyes_loop != eyes:
        print("Eyes changed")
        break

    else:
        print("Eyes not changed")
        continue

When I put the `return eyes` it exits the program, as if it were a break. — principemestizo3, Dec 26 '21 at 19:33
[What does the "yield" keyword do?](https://stackoverflow.com/a/231855) — 001, Dec 26 '21 at 19:42

JJ. · Answer 1 · 2023-07-26T09:02:32.540

3

There are multiple things not quite right:

You should close your connection if you establish it inside a function.
You should return values instead of overwriting them outside the scope. Nasty side effects can occur.

import sqlite3

def read_data(data, table):
    con = sqlite3.connect("settings.db")
    cur = con.cursor()
    data = cur.execute(f"SELECT {data} FROM {table}").fetchall()[0][0]
    con.close()
    return data


eyes = read_data("data", "eyes")

while True:
    eyes_loop = read_data("data", "eyes")

    if eyes_loop != eyes:
        print("Eyes changed")
        break

    else:
        print("Eyes not changed")
        continue

edited Jul 26 '23 at 09:02

answered Dec 26 '21 at 19:32

JJ.

76
5

It doesn't work, inside the loop while "Eyes" is the same. I want "Eyes" to change if I change it in the database. – principemestizo3 Dec 26 '21 at 19:39
Please check if read_data returns a "fitting" value and not `None` for example. Maybe print the output or use the debugger for this. If the correct value is returned we can continue debugging. @principemestizo3 – JJ. Dec 26 '21 at 19:44
I honestly don't understand. – principemestizo3 Dec 26 '21 at 19:56
In your code `print(eyes)` – JJ. Dec 26 '21 at 20:00
I do it, if in the db I have "1", 1 comes out in the loop, if I change it in the db to 0, it does not change in the loop to 0. – principemestizo3 Dec 26 '21 at 20:03
What does it say if you run this code and write `print(eyes)` after `eyes = read_data("data", "eyes")` but before the while-loop? – eandklahn Dec 26 '21 at 20:48
The same appears, only once. The number 1, what should come out. The problem is that inside it does not change, as I mentioned. – principemestizo3 Dec 26 '21 at 21:12
Is your database cached in any way? – JJ. Dec 27 '21 at 11:07
Are you printing eyes or eyes_loop in the loop? – FabianClemenz Jul 26 '23 at 09:08

score -1 · Answer 2 · answered Dec 26 '21 at 19:32

-1

The function you are using takes time to connect with database and send data back and forth. This code runs asynchronously so the loop runs and it runs past the read_data() to avoid this use async/await.

answered Dec 26 '21 at 19:32

Soyokaze

157
8

How to update variable within a while loop?

2 Answers2