How to initialize repeating tasks using Django Background Tasks?

Question

I'm working on a django application which reads csv file from dropbox, parse data and store it in database. For this purpose I need background task which checks if the file is modified or changed(updated) and then updates database. I've tried 'Celery' but failed to configure it with django. Then I find django-background-tasks which is quite simpler than celery to configure. My question here is how to initialize repeating tasks?
It is described in documentation but I'm unable to find any example which explains how to use repeat, repeat_until or other constants mentioned in documentation.
can anyone explain the following with examples please?

notify_user(user.id, repeat=<number of seconds>, repeat_until=<datetime or None>)

repeat is given in seconds. The following constants are provided: Task.NEVER (default), Task.HOURLY, Task.DAILY, Task.WEEKLY, Task.EVERY_2_WEEKS, Task.EVERY_4_WEEKS.

score 4 · Accepted Answer · answered Mar 28 '18 at 14:35

4

You have to call the particular function (notify_user()) when you really need to execute it.
Suppose you need to execute the task while a request comes to the server, then it would be like this,

@background(schedule=60)
def get_csv(creds):
    #read csv from drop box with credentials, "creds"
    #then update the DB

def myview(request):
    # do something with my view
    get_csv(creds, repeat=100)
    return SomeHttpResponse

Excecution Procedure
1. Request comes to the url hence it would dispatch to the corresponding view, here myview()
2. Excetes the line get_csv(creds, repeat=100) and then creates a async task in DB (it wont excetute the function now)
3. Returning the HTTP response to the user.

After 60 seconds from the time which the task creation, get_csv(creds) will excecutes repeatedly in every 100 seconds

answered Mar 28 '18 at 14:35

JPG

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get_csv(creds, repeat=100) is not working. repeat is an unexpected argument in function. @Jerin – Azeem Mar 28 '18 at 14:59
I don't think so, because It's worked for me well. Can you add your all related code ? – JPG Mar 28 '18 at 15:02
call the `get_csv(creds, repeat=100)` function from **Django Shell**. If you still got the `unexpected argument` error, it means you missing something in your code – JPG Mar 28 '18 at 15:04
My bad, actually I'm using Visual Studio Code and it was raising unexpected argument error, but when I tried `python manage.py process_tasks` it worked. Thank you. @Jerin – Azeem Mar 28 '18 at 15:11

score 2 · Answer 2 · answered Mar 28 '18 at 14:29

2

For example, suppose you have the function from the documentation

@background(schedule=60)
def notify_user(user_id):
    # lookup user by id and send them a message
    user = User.objects.get(pk=user_id)
    user.email_user('Here is a notification', 'You have been notified')

Suppose you want to repeat this task daily until New Years day of 2019 you would do the following

import datetime
new_years_2019 = datetime.datetime(2019, 01, 01)
notify_user(some_id, repeat=task.DAILY, repeat_until=new_years_2019)

answered Mar 28 '18 at 14:29

sytech

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There are unexpected arguments repeat and repeat_until in notify_user(some_id, repeat=task.DAILY, repeat_until=new_years_2019). Where should I call notify_user? @sytech – Azeem Mar 28 '18 at 15:00
Hmm. Are you sure that you added the decorator to the function? I just tested this and it works fine for me. – sytech Mar 28 '18 at 15:14
It worked. Problem was in visual studio code. Thank you. But `repeat=Task.DAILY` is not working. Only number args are accepted. Why so? @sytech – Azeem Mar 28 '18 at 16:25

How to initialize repeating tasks using Django Background Tasks?

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