unable to execute Celery beat the second time
Question: I am using Celery beat for getting the site data after every 10 seconds.
Therefore I update the settings in my Django project. I am using rabbitmq with
celery.

**settings.py**

    
    
    # This is the settings file
    # Rabbitmq configuration
    BROKER_URL = "amqp://abcd:abcd@localhost:5672/abcd"
    
    # Celery configuration
    CELERY_ACCEPT_CONTENT = ['json']
    CELERY_TASK_SERIALIZER = 'json'
    CELERY_RESULT_SERIALIZER = 'json'
    CELERY_TIMEZONE = 'Asia/Kolkata'
    CELERY_RESULT_BACKEND = 'djcelery.backends.database:DatabaseBackend'
    CELERYBEAT_SCHEDULER = 'djcelery.schedulers.DatabaseScheduler'
    
    
    CELERYBEAT_SCHEDULE = {
        # Executes every Monday morning at 7:30 A.M
        'update-app-data': {
            'task': 'myapp.tasks.fetch_data_task',
            'schedule': timedelta(seconds=10),
            },
    

**celery.py**

    
    
    from __future__ import absolute_import
    import os
    from celery import Celery
    from django.conf import settings
    
    # Indicate Celery to use the default Django settings module
    os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'myproject.settings')
    
    app = Celery('myapp')
    app.config_from_object('django.conf:settings')
    # This line will tell Celery to autodiscover all your tasks.py that are in
    # playstore folders
    app.autodiscover_tasks(lambda: settings.INSTALLED_APPS)
    
    app_keywords = Celery('keywords')
    app_keywords.config_from_object('django.conf:settings')
    # This line will tell Celery to autodiscover all your tasks.py that are in
    # keywords folders
    app_keywords.autodiscover_tasks(lambda: settings.INSTALLED_APPS)
    
    
    app1 = Celery('myapp1')
    app1.config_from_object('django.conf:settings')
    # This line will tell Celery to autodiscover all your tasks.py that are in
    # your app folders
    app1.autodiscover_tasks(lambda: settings.INSTALLED_APPS)
    

**tasks.py**

    
    
    @task(bind=True)
    def fetch_data_task(self, data):
        logger.info("Start task")
        import pdb;pdb.set_trace()
        # post the data to view
        headers, cookies = utils.get_csrf_token()
        requests.post(settings.SITE_VARIABLES['site_url'] + "/site/general_data/",
                      data=json.dumps(data), headers=headers, cookies=cookies
                      )
        if data['reviews']:
            reviews_data = {'app_id': data['app_data'][
                'app_id'], 'reviews': data['reviews'][0]}
            requests.post(settings.SITE_VARIABLES['site_url'] + "/site/blog/reviews/",
                          data=json.dumps(reviews_data), headers=headers, cookies=cookies
                          )
        logger.info("Task fetch data finished")
    

Now once I call `fetch_data_task` in my api after login to the site, The task
is queued in rabbimq and then It should the call the function along with the
arguments.

Here is the line where I am calling the task for the very first time

`tasks.fetch_data_task.apply_async((data,))`

This queues the task and the task executes each time but it gives me the
following error

> [2016-09-13 18:57:43,044: ERROR/MainProcess] Task
> playstore.tasks.fetch_data_task[3b88c6d0-48db-49c1-b7d1-0b8469775d53]
>
> raised unexpected: TypeError("fetch_data_task() missing 1 required
> positional argument: 'data'",)
>
> Traceback (most recent call last):
>
> File "/Users/chitrankdixit/.virtualenvs/hashgrowth->
> >dev/lib/python3.5/site-packages/celery/app/trace.py", line 240, in
> >trace_task R = retval = fun(*args, **kwargs) File
> "/Users/chitrankdixit/.virtualenvs/hashgrowth->dev/lib/python3.5/site-
> packages/celery/app/trace.py", line 438, in >**protected_call** return
> self.run(*args, **kwargs) TypeError: fetch_data_task() missing 1 required
> positional argument: 'data'

If anyone has worked with celery and rabbitmq and also worked with periodic
task using celery please suggest me to execute the tasks properly.


Answer: The exception tells you what the error is: your task expects a positional
argument, but you do not provide any arguments in your schedule definition.

    
    
    CELERYBEAT_SCHEDULE = {
        # Executes every Monday morning at 7:30 A.M
        'update-app-data': {
            'task': 'myapp.tasks.fetch_data_task',
            'schedule': timedelta(seconds=10),
            'args': ({
                # whatever goes into 'data' 
            },)  # tuple with one entry, don't omit the comma
        },
    

Calling the task from any other place in your code does not have any effect on
the schedule.

