Django - how to send mail 5 days before event?

I'm Junior Django Dev. Got my first project. Doing quite well but senior dev that teaches me went on vacations....

I have a Task in my company to create a function that will remind all people in specyfic Group, 5 days before event by sending mail.

There is a TournamentModel that contains a tournament_start_date for instance '10.08.2018'.

Player can join tournament, when he does he joins django group "Registered".

I have to create a function (job?) that will check tournament_start_date and if tournament begins in 5 days, this function will send emails to all people in "Registered" Group... automatically.

How can I do this? What should I use? How to run it and it will automatically check? I'm learning python/django for few months... but I meet jobs fot the first time ;/

I will appreciate any help.

Solution

If you break this down into two parts, it will be easier. The parts are

Send the reminder emails
Run the script every day

For the first part, I would begin by installing the outstanding django-extensions package so that it is easy to run scripts. (Check your INSTALLED_APPS, you may have it already.) Having the python-dateutil package will be helpful too.

Then I would write my script. Let's say your app is called "myapp". Create a directory under "myapp" called "scripts", and create an empty __init__.py in there.

Now create your script file in "myapp/scripts/remind_players.py". It will look something like this:

from datetime import date
from datutil.relativedelta import relativedelta
from django.mail import send_mail  # I think this is right.
from myapp.models import Tournament

def run():
    # find our tournaments that start five days from now.
    for tournament in Tournament.objects.filter(tournament_start_date=date.today() + relativedelta(days=5)):

        # find the players that are registered for the tournament
        for player in tournament.registered_player_set():
            send_mail(...)

To run your script manually, you would run

python manage.py runscript remind_players

(PROTIP: make sure that your test database only contains your own email address. It would be embarrassing to have your test system sending out emails to everyone.)

(PROTIP: you can also configure Django to put email messages in the logs, rather than actually sending them.)

For the second part, you'll have to find a way to schedule the job to run every day. Usually, your operating system will provide a way to do that. If you're on Unix/Linux, you'll use "cron". If you're on Windows, you'll use "Scheduled Tasks". (There are other options for scheduling, but these are the most common.)