A generic application to follow a resource with multiple backends
Project description
A generic application to follow a resource with multiple backends (db, redis, etc.)
Compatibility
This library is compatible with:
python2.6, django1.4
python2.6, django1.5
python2.6, django1.6
python2.7, django1.4
python2.7, django1.5
python2.7, django1.6
python3.3, django1.5
python3.3, django1.6
If I’m a liar, you can ping me.
Installation
Either check out the package from GitHub or it pull from a release via PyPI
pip install django-sequere
Add sequere to your INSTALLED_APPS
INSTALLED_APPS = ( 'sequere', )
Usage
In Sequere any resources can follow any resources and vice versa.
Let’s say you have two models:
# models.py from django.db import models class User(models.Model): username = models.Charfield(max_length=150) class Project(models.Model): name = models.Charfield(max_length=150)
Now you to register them in sequere to identify them when a resource is following another one.
# sequere_registry.py from .models import Project, User import sequere sequere.register(User) sequere.register(Project)
Sequere uses the same concepts as Django Admin, so if you have already used it, you will not be lost.
Last step is to tell Sequere to autodiscover your registered models:
# urls.py from django.conf.urls.defaults import patterns import sequere; sequere.autodiscover() urlpatterns = patterns( '', # Your urls here )
You can now use Sequere like any other application, let’s play with it:
In [1]: from sequere.models import (follow, unfollow, get_followings_count, is_following, get_followers_count, get_followers, get_followings) In [2]: from myapp.models import User, Project In [3]: user = User.objects.create(username='thoas') In [4]: project = Project.objects.create(name'La classe americaine') In [5]: follow(user, project) # thoas will now follow "La classe americaine" In [6]: is_following(user, project) True In [7]: get_followers_count(project) 1 In [8]: get_followings_count(user) 1 In [9]: get_followers(user) [] In [10]: get_followers(project) [(<User: thoas>, datetime.datetime(2013, 10, 25, 4, 41, 31, 612067))] In [11]: get_followings(user) [(<Project: La classe americaine, datetime.datetime(2013, 10, 25, 4, 41, 31, 612067))]
If you are as lazy as me to provide the original instance in each sequere calls, use SequereMixin:
# models.py from django.db import models from sequere.mixin import SequereMixin class User(SequereMixin, models.Model): username = models.Charfield(max_length=150) class Project(SequereMixin, models.Model): name = models.Charfield(max_length=150)
Now you can use calls directly from the instance:
In [1]: from myapp.models import User, Project In [2]: user = User.objects.create(username='thoas') In [3]: project = Project.objects.create(name'La classe americaine') In [4]: user.follow(project) # thoas will now follow "La classe americaine" In [5]: user.is_following(project) True In [6]: project.get_followers_count() 1 In [7]: user.get_followings_count() 1 In [8]: user.get_followers() [] In [9]: project.get_followers() [(<User: thoas>, datetime.datetime(2013, 10, 25, 4, 41, 31, 612067))] In [10]: user.get_followings() [(<Project: La classe americaine, datetime.datetime(2013, 10, 25, 4, 41, 31, 612067))]
So much fun!
Backends
sequere.backends.database.DatabaseBackend
A database backend to store your follows in you favorite database using the Django’s ORM.
To use this backend you will have to add sequere.backends.database to your INSTALLED_APPS
INSTALLED_APPS = ( 'sequere', 'sequere.backends.database', )
The follower will be identified by the couple (from_identifier, from_object_id) and the following by (to_identifier, to_object_id).
Each identifiers are taken from the registry. For example, if you want to create a custom identifier key from a model you can customized it like so:
# sequere_registry.py from myapp.models import Project from sequere.base import ModelBase import sequere class ProjectSequere(ModelBase): identifier = 'projet' # the french way ;) sequere.registry(Project, ProjectSequere)
sequere.backends.redis.RedisBackend
We are using exclusively Sorted Sets in this Redis implementation.
Create a uid for a new resource
INCR sequere:global:uid => 1 SET sequere:uid:{identifier}:{id} 1 HMSET sequere:uid::{id} identifier {identifier} object_id {id}
Store followers count
INCR sequere:uid:{to_uid}:followers:count => 1 INCR sequere:uid:{to_uid}:followers:{from_identifier}:count => 1
Store followings count
INCR sequere:uid:{from_uid}:followings:count => 1 INCR sequere:uid:{from_uid}:followings:{to_identifier}:count => 1
Add a new follower
ZADD sequere:uid:{to_uid}:followers {from_uid} {timestamp} ZADD sequere:uid:{to_uid}:followers:{from_identifier} {from_uid} {timestamp}
Add a new following
ZADD sequere:uid:{from_uid}:followings {to_uid} {timestamp} ZADD sequere:uid:{from_uid}:followings{to_identifier} {to_uid} {timestamp}
Retrieve the followers uids
ZRANGEBYSCORE sequere:uid:{uid}:followers -inf +inf
Retrieve the followings uids
ZRANGEBYSCORE sequere:uid:{uid}:followings =inf +inf
With this implementation you can retrieve your followers ordered
ZREVRANGEBYSCORE sequere:uid:{uid}:followers +inf -inf
sequere.backends.redis.RedisFallbackBackend
If you want to store follows in Redis and in your database with asynchronous tasks, this backend is for you.
To run asynchronous tasks, we are using Celery tasks.
To use this backend you will have to install both sequere.backends.database and sequere.backends.redis to your INSTALLED_APPS
INSTALLED_APPS = ( 'sequere', 'sequere.backends.database', 'sequere.backends.redis', )
Configuration
SEQUERE_BACKEND_CLASS
The backend used to store follows
Defaults to sequere.backends.database.Databasebackend.
SEQUERE_REDIS_CONNECTION
A dictionary of parameters to pass to the to Redis client, e.g.:
SEQUERE_REDIS_CONNECTION = { 'host': 'localhost', 'port': 6379, 'db': 0, }
Alternatively you can use a URL to do the same:
SEQUERE_REDIS_CONNECTION = 'redis://username:password@localhost:6379/0'
SEQUERE_REDIS_CONNECTION_CLASS
An (optional) dotted import path to a connection to use, e.g.:
SEQUERE_REDIS_CONNECTION_CLASS = 'myproject.myapp.mockup.Connection'
SEQUERE_REDIS_PREFIX
The (optional) prefix to be used for the key when storing in the Redis database. Defaults to ‘sequere:’. E.g.:
SEQUERE_REDIS_PREFIX = 'sequere:myproject:'
Defaults to sequere:.
Resources
haplocheirus: a Redis backed storage engine for timelines written in Scala
Case study from Redis documentation: write a twitter clone
Amico: relationships backed by Redis
django-constance: a multi-backends settings management application
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