Cool Down System

Django-snitch implements a cool down system, so a user can set a limit of how many notification will be sent to a user in a time period.

import snitch

SPAM = "spam"


@snitch.register(SPAM)
class SpamHandler(snitch.EventHandler):

    cool_down_manager_class = snitch.CoolDownManager
    cool_down_attempts = 5
    cool_down_time = 5  # In seconds
    notification_backends = [PushNotificationBackend]

cool_down_manager_class

Default: None`

Indicates the class that should be used to handle the cool down. It is set to None by default, and you should specify the class to use this function.

Django-snitch comes with the class snitch.CoolDownManager that can be used. It uses Django’s cache framework to handle the count of how many notifications are sent to a user.

cool_down_attempts

Default: 1

It handles the number of notifications that have to be sent in order to stop the sending. This can be an int, a callable that returns an integer number or a string and receives two arguments, and snitch.EventHandler and a receiver as a Django Model. If it’s a string, it should reference a method in the handler with and argument, the receiver .

cool_down_time

Default: 0

It handles the number of seconds to wait until the notifications will be send again. This can be an int, a callable that returns an integer number or a string and receives two arguments, and snitch.EventHandler and a receiver as a Django Model. If it’s a string, it should reference a method in the handler with and argument, the receiver .

cool_down_cache_alias

Default: default

This property is used by snitch.CoolDownManager and allows to use a different alias for the cache.

The cache key is created using the event verb and the receiver data, app label, model name and primary key.

class CoolDownManager(AbstractCoolDownManager):

    def _key(self, receiver: "models.Model", suffix: str = "") -> str:
        """Get the cache key used by the cool down manager."""
        if receiver.pk is None:
            raise AttributeError("The receiver should have a primary key.")
        key = f"[{self.prefix}]cool-down-{self.event_handler.event.verb}-{receiver._meta.app_label}-{receiver._meta.model_name}-{receiver.pk}"
        if suffix:
            key = f"{key}-{suffix}"
        return key

Therefore, the counter by default is unique for each receiver and each event verb.

Cool Down Manager

In the EventHandler it can be specified a different CoolDownManager class by changing the attribute cool_down_manager_class in the EventHandler.

import snitch
from snitch.cooldowns import AbstractCoolDownManager

SPAM = "spam"


class CustomCoolDownManager(AbstractCoolDownManager):

    def should_notify(self, receiver: "models.Model") -> bool:
        """By default, always notify."""
        return True

    def should_send(self, receiver: "models.Model") -> bool:
        """By default, always send."""
        return True


@snitch.register(SPAM)
class SpamHandler(snitch.EventHandler):
    cool_down_attempts = 5
    cool_down_time = 5
    cool_down_manager_class = CustomCoolDownManager
    notification_backends = [PushNotificationBackend]