Python 3.6 - 'NoneType' test fails

Question

I am reading from an sqlite3 database and filtering out NoneType, since I only want values which are not None. I tried both methods suggested here, with identical results. This leads me to think that the below if-statement is correct, but I am missing something more fundamental. Any suggestions are appreciated.

Reading from Databse

        conn.commit()
        c.execute("SELECT tact FROM LineOEE03 ORDER BY tact DESC LIMIT 1")
        current_tact = c.fetchone()

NoneType test

        if current_tact is not None:
            current_tact = int(current_tact[0])
        else:
            current_tact = 60

Error

current_tact = int(current_tact[0])
TypeError: int() argument must be a string, a bytes-like object or a number, not 'NoneType'

Why am I getting this error if I am specifically tageting not None types in my if-statement?
What is the correct way to do this, such when the value is None I can assign a pre-defined value?

is `current_tact = [None]` (or a list/tuple containing `None` as first element)? — hiro protagonist, Aug 29 '18 at 06:20
Try `print(current_tact)` and you'll immediately see the problem. — Aran-Fey, Aug 29 '18 at 06:27
@hiroprotagonist, absolutely right. Output is:`(None,)` Thanks for guiding me in the right direction Aran-Fey, very basic mistake from my end. — rrz0, Aug 29 '18 at 06:29

score 3 · Accepted Answer · answered Aug 29 '18 at 06:27

You can either add an additional test to check if the first item in the list is not None, which is what you're actually trying to convert to an integer:

if current_tact is not None and current_tact[0] is not None:
    current_tact = int(current_tact[0])

or use a try-except block to avoid having to test at all:

try:
    current_tact = int(current_tact[0])
except TypeError:
    current_tact = 60

Python 3.6 - 'NoneType' test fails

Reading from Databse

NoneType test

Error

1 Answers1