datetime.date.today() always returns the same value-CodePudding

I have a Django project. I use nginx gunicorn. The views.py file has a combined_data() function that creates and returns an HTML page. As you can see, I am passing the objects in 'rows' and the current date in 'time'.

A function that returns objects looks like this

The problem is that in this function, reporting_date always gets the value it got the first time it was called. For example, I do "sudo systemctl restart gunicorn" and open this page in the browser. reporting_date will be equal to today. If I open the page tomorrow, reporting_date will not change its value.

Initially, I assumed that datetime.date.today () does not work correctly, so I added the 'time' parameter to views.py (first screen), but the date is always correct there. Then I thought that the default value of the parameters of the get_combined() function (second screen) is somehow cached, so I added the r_int parameter, which receives a random value, but everything works correctly here. r_int always gets a new value.

Now, I have to call "sudo systemctl restart gunicorn" every day to make the page work properly ((

Any ideas how to fix this problem? Thanks

CodePudding user response：

The default value for the parameter reported_date is the value of the first time the function gets imported. You should do something like

def get_combined(reported_date=None, ...):
    reported_date = reported_date or datetime.datetime.today()
    ...

CodePudding user response：

Instead of

def get_combined(reported_date=datetime.datetime.today()):

use

def get_combined():
    reported_date = datetime.datetime.today()

What I tried:-

>>> def c(day = datetime.today()):
        print(day)

    
>>> c()
>>> 2022-10-27 15:44:57.593444
>>> c()
>>> 2022-10-27 15:44:57.593444

>>> def c():
        day = datetime.today()
        print(day)

    
>>> c()
>>> 2022-10-27 15:56:02.459517
>>> c()
>>> 2022-10-27 15:56:04.630902

As @OldBill mentioned: When you declare a default value for a function parameter it is evaluated once and not every time the function is called