Python Containers Simple Models on NoSQL (and SQL) storage. Supporting: Redis, Riak, MongoDB, Sqlite and MySQL

TODO Redisco allows you to store objects in Redis. It is inspired by the Ruby library Ohm and its design and code are loosely based on Ohm and the Django ORM. It is built on top of redis-py. It includes container classes that allow easier access to Redis sets, lists, and sorted sets.

TODO Redisco requires redis-py 2.0.0 so get it first.

pip install redis

Then install redisco.

pip install redisco

TODO The documentation is available at : https://redisco.readthedocs.org

from datetime import datetime
import modelplus

class Person(modelplus.Model):
    name        = modelplus.Attribute(required=True)
    created_at  = modelplus.DateTimeField(default=datetime.now)
    fave_colors = modelplus.ListField(str)

>>> person = Person(name="Conchita")
>>> person.is_valid()
True
>>> person.save()
True
>>> conchita = Person.objects.filter(name='Conchita')[0]
>>> conchita.name
'Conchita'
>>> conchita.created_at
datetime.datetime(2010, 5, 24, 16, 0, 31, 954704)

IntegerField

Stores an int. Ints are stringified using unicode() before saving.

StringField

Stores an int. Ints are stringified using unicode() before saving.

Counter

An IntegerField that can only be accessed via Model.incr and Model.decr.

DateTimeField

Can store a DateTime object. Saved in the Redis store as a float.

DateField

Can store a Date object. Saved in Redis as a float.

FloatField

Can store floats.

BooleanField

Can store bools. Saved in Redis as 1's and 0's.

ReferenceField

Can reference other redisco model.

ListField

Can store a list of unicode, int, float, as well as other redisco models.

required

If True, the attirbute cannot be None or empty. Strings are stripped to check if they are empty. Default is False.

default

Sets the default value of the attribute. Default is None. If default is a function, set it to the result of the function.

indexed

If True, redisco will create index entries for the attribute. Indexes are used in filtering and ordering results of queries. For large bodies of strings, this should be set to False. Default is True.

validator

Set this to a callable that accepts two arguments -- the field name and the value of the attribute. The callable should return a list of tuples with the first item is the field name, and the second item is the error.

unique

The field must be unique. Default is False.

DateField and DateTimeField Options

auto_now

Automatically set the datetime/date field to now/today everytime the object is saved. Default is False.

You can specify some options in your Model to control the behaviour of the back scene.

::

class User(models.Model):

firstname = models.StringField() lastname = models.StringField()

@property def fullname(self): return "%s %s" % (self.firstname, self.lastname)

class Meta:

indices = ['fullname'] db = redis.Redis(host="localhost", db="6666") key = 'Account'

indices is used to add extra indices that will be saved in the model. db object will be used instead of the global client key will be used as the main key in the redis Hash (and sub objects) instead of the class name.

To save an object, call its save method. This returns True on success (i.e. when the object is valid) and False otherwise.

Calling Model.is_valid will validate the attributes and lists. Model.is_valid is called when the instance is being saved. When there are invalid fields, Model.errors will hold the list of tuples containing the invalid fields and the reason for its invalidity. E.g. [('name', 'required'),('name', 'too short')]

Fields can be validated using the validator argument of the attribute. Just pass a callable that accepts two arguments -- the field name and the value of the attribute. The callable should return a list of errors.

Model.validate will also be called before saving the instance. Override it to validate instances not related to attributes.

def not_me(field_name, value):
    if value == 'Me':
        return ((field_name, 'it is me'),)

class Person(models.Model):
    name = models.Attribute(required=True, validator=not_me)
    age = models.IntegerField()

    def validate(self):
        if self.age and self.age < 21:
            self._errors.append(('age', 'below 21'))

>>> person = Person(name='Me')
>>> person.is_valid()
False
>>> person.errors
[('name', 'it is me')]

Queries are executed using a manager, accessed via the objects class attribute.

Person.objects.all()
Person.objects.filter(name='Conchita')
Person.objects.filter(name='Conchita').first()
Person.objects.all().order('name')
Person.objects.filter(fave_colors='Red')

All models and containers use a global Redis client object to interact with the key-value storage. By default, it connects to localhost:6379, selecting db 0. If you wish to specify settings:

import redisco
redisco.connection_setup(host='localhost', port=6380, db=10)

The arguments to connect are simply passed to the redis.Redis init method.

For the containers, you can specify a second argument as the Redis client. That client object will be used instead of the default.

>>> import redis >>> r = redis.Redis(host='localhost', port=6381) >>> Set('someset', r)

Most of the concepts are taken from Soveran's Redis related Ruby libraries. cyx for sharing his expertise in indexing in Redis. Django, of course, for the popular model API.