Welcome to Rohypnol’s documentation!

Rohypnol offers syntactic sugar to easily connect Django signals to cache keys deletion.

Requirements

Python 2	> 2.7
Python 3	>= 3.2
Django	>= 1.6

Installation

Install the rohypnol package:

pip install rohypnol

Make sure rohypnol is listed among your INSTALLED_APPS:

INSTALLED_APPS = [
    # [...]
    'rohypnol',
]

Usage

The code below will connect the built-in Django post_save signal to cache.delete('article_list') when the sender is an Article instance.

from myapp.models import Article
from rohypnol.register import rohypnol

rohypnol.register(Article, 'article_list')

In your urls.py file:

from rohypnol.register import connect_all_signals

urlpatterns = ...

connect_all_signals()

This is roughly equivalent to:

from django.db.models.signals import post_save
from django.core.cache import cache

from myapp.models import Article

def delete_cache(key):
    cache.delete(key)

post_save.connect(delete_cache, sender=Article)

Actually the callback function is defined as a closure. Have a look at the RohypnolRegister class if interested.

Advanced usage

The example above is pretty trivial and, in fact, useless. But you can save yourself a lot of typing with this application by doing something like this:

from myapp.models import Article, Paragraph, Category
from rohypnol import rohypnol

rohypnol.register((Article, Paragraph, Category),
                  ('article_list', 'top_articles'))

Basically, the register method accepts three arguments:

1. models, which can be a single model class or a list of models that will be considered as the sender of the signals.

2. keys, which can be a string or a list of strings. These will be the cache keys that are going to be deleted.

3. signals, which can be a signal instance or a list of signals. If none is specified, it defaults to built-in Django post_save of the models above.

A more complete example:

from django.db.models.signals import post_save
from django.dispatch import Signal

custom_signal = Signal()

rohypnol.register((Article, Category, Paragraph),
                  ('article_list', 'top_articles'),
                  (post_save, custom_signal))

This will delete the cache fragments identified by the keys 'article_list' and 'top_articles' whenever a post_save or a custom_signal is sent by one of the listed models.

Note

As noted in Django documentation, the models.py is the best place to connect signals and you should do the same with rohypnol.register if you are using Django < 1.7.

Starting from that version, you should use the ready() method of your application configuration class. See the documentation for further explanation.

Also, it is fundamental to call the connect_all_signals method in your urls.py, because it is executed only once, after all you models have been loaded.

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