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Django custom field to implement the strategy pattern

Project Description

Set of custom fields useful to implement the Strategy Pattern with Django models.

The Strategies are displayed in SelectBoxes as standard choice field

This package provides the following custom fields:

  • StrategyField
  • MultipleStrategyField
  • StrategyClassField
  • MultipleStrategyClassField

The StrategyField can be accessed as instance of the model with an attribute context that points to model that ‘owns’ the field (inverse relation). So:

Example

from strategy_field.fields import StrategyField
from django.core.mail.backends.filebased.EmailBackend


class Event(models.Model):
    backend = StrategyField()

Event(sender='django.core.mail.backends.filebased.EmailBackend')

Use case

As example we can imagine an application that manages \(Events\) that need to be notified to users. Each \(Occurrence\) of \(Event\) can be notified using different transport, (email, sms,…). We want to be able to add/change the way we send notification, per event basis, simply using the Django admin panel.

from strategy_field.fields import StrategyField

from strategy_field.registry import Registry
from strategy_field.fields import StrategyField

class TransportRegistry(Registry)
    pass

class AbstractStrategy(object):
    def __init__(self, context):
        self.context = context

    def send(self):
        raise NotImplementedError

class EmailStrategy(AbstractTransport):
    def send(self):
        ...

class SMSStrategy(AbstractTransport):
    def send(self):
        ...
registry = TransportRegistry(AbstractTransport)
registry.register(EmailStrategy)
registry.register(SMSStrategy)

class Event(models.Model):
    sender = StrategyField(registry)

Event.objects.get_or_create(sender=EmailStrategy)
...
...
e = Event.objects.get(sender=EmailStrategy)
e.sender.send() # e.sender.context == e
Release History

Release History

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1.0

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0.1

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django-strategy-field-1.0.tar.gz (16.7 kB) Copy SHA256 Checksum SHA256 Source Sep 19, 2016

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