datetime Module

date Class

import datetime
birthdate = datetime.date(2005, 1, 1) # Year, Month, Day
print(birthdate)

[!TIP]

When coding and developing modules in Python try to avoid giving the same name to a class as your module since it can be quite confusing. Like what you can see here, datatime.datetime!

Learn more about naming conventions in Python here. This is supper important since if you pick a bad name it will be hard to change later and also it became a tech debt which its interest rate will grow over time.

• The returned value might uses the locale-settings of your system, but in some cases it might not. This makes your code less reliable, thus we must specify the locale to be safe.

  from datetime import date
  import locale
  locale.setlocale(locale.LC_ALL, "")
  print(date(2004, 12, 20))
  

  Caution:

  • This should be done in the main file of your project and not in the modules.
  • The second parameter of setlocale is a string that specifies the locale to be used, e.g. en_US.utf-8 or de_DE.utf-8.
    • Empty string means the default system locale.
  • The locale should be installed on your system otherwise your code will crash.

strftime

from datetime import date
birthdate = date(2004, 12, 20)
print(birthdate.strftime("%Y.%m.%d"))  # 2004.12.20
print(f"{birthdate.year}.{birthdate.month}.{birthdate.day}")

• This method uses the locale settings of the system it is running on.

[!INFO]

You can thank C programmers who have the religious belief that you only get so many vowels in your lifetime; the more vowels they type, the sooner they will die. Yes, it is string-format-time, and strptime is string-parse-time. Why the methods were not simply named “time_to_string” and “time_from_string” like sensible people would do is beyond understanding.

— Ref

Getting The Current Date & Time

now	today	utcnow
```py from datetime import datetime print(datetime.now()) ```	```py from datetime import datetime print(datetime.today()) ```	```py from datetime import datetime print(datetime.utcnow()) ```

[!NOTE]

Python doc states that date.now() is the preferred approach compare to date.today() and date.utcnow() (ref).

We can get the difference of times like this:

from datetime import datetime
birthdate = datetime(2005, 1, 1)
today = datetime.today()
print(today - birthdate)

[!CAUTION]

You cannot add two dates together, it will crash your app, for adding you need to use timedelta:

from datetime import date
date1 = date(2004, 12, 31)
date2 = date(2005, 1, 1)
print(date1 + date2)

timedelta

from datetime import date, timedelta
duration = timedelta(days=10)
opening_date = date(2025, 7, 20)
end_date = opening_date + duration
print(end_date)

Note: date object does not have a time component, meaning if we specify hour, it will be lost. E.g. timedelta(days=10, hours=1). But increasing it to 24 will make it a whole day, so it will change the returned value.

time

from datetime import time
print(time(12, 30))

• A (local) time of day.
• Independent of any particular day.
• Subject to adjustment via a tzinfo object.

[!NOTE]

You cannot subtract instances of times, i.e. the following code crashes:

from datetime import time
print(time(12, 10) - time(12, 30))

Traceback (most recent call last):
  File "/home/kasir/projects/python/main.py", line 2, in <module>
    print(time(12, 10) - time(12, 30))
          ~~~~~~~~~~~~~^~~~~~~~~~~~~~
TypeError: unsupported operand type(s) for -: 'datetime.time' and 'datetime.time'

ISO 8601

• The standard way of representing date and time.
• The support for this is limited in Python version 3.11 and below.
• The format is:
  • YYYY-MM-DDTHH:MM:SS.mmmmmm±HH:MM.
  • T is the separator between date and time.

isoformat	date.fromisoformat
```py from datetime import datetime print(datetime(2023, 1, 1).isoformat()) ```	```py from datetime import date print(date.fromisoformat("2023-01-01")) ```

YouTube/Aparat

• https://youtu.be/d1SjnLZ65MU.
• https://aparat.com/v/dqu1qmb.