Try/catch to close a postgres db connection in python

Question

I was told that currently, what I have below will cause the database to stay open indefinitely if an error is thrown. How do I use the try catch statement to make sure that the connection closes if an error occurs?

connection = psycopg2.connect(some_stuff_in_here)
print("Connected to DB")
cursor = connection.cursor()

if __name__ == '__main__':
   does_something()

cursor.close()
connection.close()
print("Disconnected from DB")

Do I do the following? I feel it still won't work because if an error occurs while trying to close the connection, the except block will still not be able to close it.

try:
   cursor.close()
   connection.close()
except:
   print("Database Process Error")
   cursor.close()
   connection.close()

try: except: finally will be the solution

Akash Pagar
– Akash Pagar

2019-09-30 17:00:56 +00:00
Commented Sep 30, 2019 at 17:00 — Akash Pagar
– Akash Pagar, Commented Sep 30, 2019 at 17:00

Jeremy · Accepted Answer · 2019-09-30 17:20:05Z

1

It's probably easiest to use the connection and cursor as context managers (the with statement):

From the docs:

with psycopg2.connect(your_stuff_in_here) as conn:
    with conn.cursor() as curs
        curs.execute('SELECT * FROM test')

This will automatically clean up after any errors. If you need more fine-grained control over the errors you can use try/catch/finally.

answered Sep 30, 2019 at 17:20

Jeremy

6,77322 silver badges21 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

jjanes · Accepted Answer · 2019-09-30 17:46:28Z

0

The connection will close when the python process exits. Unless the python process is a long-running daemon, there is nothing to worry about.

Trying to catch this seems pointless. If the connection refuses to close in the normal course, what are you going to do about it in the exceptional case? Presumably it still won't close there either, as nothing has changed. About the only way catching this makes sense is if the python is a long-running process, and the exception condition results in an abort of that process which would otherwise not occur.

answered Sep 30, 2019 at 17:46

jjanes

44.9k5 gold badges39 silver badges48 bronze badges

Collectives™ on Stack Overflow

Try/catch to close a postgres db connection in python

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related