Strange error in flask:

Question

The following code (edited this based on the first answer):

time_difference_in_seconds = int(
    (datetime.combine(date.today(), max_time)
     - datetime.combine(date.today(), min_time)
).total_seconds())
[...]
for date in dates:
[...]

gives me this error:

UnboundLocalError: local variable 'date' referenced before assignment

Just to be clear, I have imported date and datetime from datetime. Moreover, when I execute the code in the werkzeug debugger, it works just fine and gives me the desired result:

[console ready]
>>> int((datetime.combine(date.today(), max_time)
        - datetime.combine(date.today(), min_time)).total_seconds())
46800

In fact, I have used the same function in different views, and it doesn't cause any errors there.

What causes this strange error and how can I resolve it?

Answer 1

You're assigning some value to date later in the function, wich caused Python to consider date as a reference to the local variable instead of the imported module you expected

Rename this date variable inside the function to solve the problem.

Answer 2

I guess you must assign something to date in your function like this:

def somefunc():
    time_difference_in_seconds = int(
        (datetime.combine(date.today(), max_time)
         - datetime.combine(date.today(), min_time)
    ).total_seconds())
    date = ...

renaming the variable will resolve this problem.