Synopsis

This module is an add-on for Django REST Framework, based on Django LDP add-on. It serves django models for a notifications component, respecting the Linked Data Platform convention. It aims at enabling people with little development skills to serve their own data, to be used with a LDP application.

Models

Notification

An object representing a notification. A notification has the following fields:

Field	Type	Default	Description
user	ForeignKey to User		User targeted by the notification.
author	LDPUrlField		ID of the user at the origin of the notification
object	LDPUrlField		ID of the object which is the subject of the notification
type	CharField		Short description of the notification
summary	TextField		Longer description of the notification
date	DateTimeField	now	Date of the notification
unread	BooleanField	True	Indicates that the notification has not been read yet.

NB: You can access to all the notifications of a User at [host]/users/[id]/inbox

Subscription

An object allowing a User to be notified of any change on a resource or a container. A subscription has the following fields:

Field	Type	Default	Description
object	URLField		ID of the resource or the container to watch
inbox	URLField		ID of the inbox to notify when the resource or the container change
field	CharField		(optional) if set, then object['field'] will be sent in the notification, not object

For convenience, when you create a subscription on an object, DjangoLDP-Notification will parse the object for any one-to-many nested field relations. It will then create nested-subscriptions, i.e. a subscription on the nested field which sends an update to the same inbox, passing the parent model. If this behaviour is undesired you can delete the Subscription instance

You can automatically create required subscriptions based on your settings.py with this management command:

./manage.py create_subscriptions

Middlewares

There is a CurrentUserMiddleware that catches the connected user of the last performed HTTP request and adds to every model before it is saved. This is useful if you need to get the connected user that performed the last HTTP request in a pre_saved signal. You can get it by using the following line :

getattr(instance, MODEL_MODIFICATION_USER_FIELD, "Unknown user")

MODEL_MODIFICATION_USER_FIELD is a constant that lies in djangoldp_notification.middlewares and instance is the instance of your model before save in DB.

Signals

Create notification on subscribed objects

When an object is saved, a notification is created for all the subscriptions related to this object.

Send email when new notification

When a notification is created, an email is sent to the user.

Django commands

This package also bring a few Django managment command. You can use them at the root of your SIB project.

mock_notification

This lets you create mocked notifications. Useful for develpment.

Usage:

python3 manage.py mock_notification [--size <number_of_notifications>]

Will create the number of dummy notifications specified by --size. By default, 0.

suppress_old_notifications

Will suppress old notification. This is a maintenance command to prevent the server to blow under the weight of your notifications.

Usage:

python3 manage.py suppress_old_notifications [--older <time_period>]

This will erase notification older than the time period specified by --older. By default, 72h ago. time_period is expressed in minutes. d, h and m suffix are also valid to express periods in days, hours and minutes.

Examples:

# Default. Will delete notifications older than 72h
python3 manage.py mock_notification
# Default. Will delete notifications older than 10 minutes ago
python3 manage.py mock_notification --older 10
# Default. Will delete notifications older than 10 days ago
python3 manage.py mock_notification --older 10d
# Default. Will delete notifications older than 10 hours ago
python3 manage.py mock_notification --older 10h

Check your datas integrity

Because of the way the DjangoLDP's federation work, you may want to send your notification to every subscribers sometimes.

Follow the check_integrity command of DjangoLDP to get how much resources will be impacted:

./manage.py check_integrity

Then run this command to send notifications:

./manage.py check_integrity --send-subscription-notifications

Notice that you may have to restart your ActivityQueue or your DjangoLDP server, depending on how you configured the ActivityQueueService