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django-crashlog
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django-crashlog

Strategy Pattern with Django models

by Stefano Apostolico

1.2.0 (see all)License:BSD
pypi i django-crashlog
Readme

=====================

django-strategy-field

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

.. code-block:: python

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.

.. code-block:: python

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

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(AbstractStrategy)
registry.register(EmailStrategy)
registry.register(SMSStrategy)

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

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

More examples

Use callable


.. code-block:: python

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

    registry1 = Registry()
    registry2 = Registry()

    class A(model):
        sender = StrategyField(registry=lambda model: model._registry)
        class Meta:
            abstract = True

    class C1(A):
        _registry = registry1
        class Meta:
            abstract = True

    class C2(A):
        _registry = registry2
        class Meta:
            abstract = True


Project links
=============

+--------------------+----------------+--------------+---------------------------+
| Stable             | |master-build| | |master-cov| |                           |
+--------------------+----------------+--------------+---------------------------+
| Development        | |dev-build|    | |dev-cov|    |                           |
+--------------------+----------------+--------------+---------------------------+
| Project home page: |https://github.com/saxix/django-strategy-field             |
+--------------------+---------------+-------------------------------------------+
| Issue tracker:     |https://github.com/saxix/django-strategy-field/issues?sort |
+--------------------+---------------+-------------------------------------------+
| Download:          |http://pypi.python.org/pypi/django-strategy-field/         |
+--------------------+---------------+-------------------------------------------+

.. _Strategy Pattern: http://www.oodesign.com/strategy-pattern.html

.. |master-build| image:: https://secure.travis-ci.org/saxix/django-strategy-field.png?branch=master
    :target: http://travis-ci.org/saxix/django-strategy-field/

.. |master-cov| image:: https://codecov.io/github/saxix/django-strategy-field/coverage.svg?branch=master
    :target: https://codecov.io/github/saxix/django-strategy-field?branch=develop


.. |dev-build| image:: https://secure.travis-ci.org/saxix/django-strategy-field.png?branch=develop
    :target: http://travis-ci.org/saxix/django-strategy-field/

.. |dev-cov| image:: https://codecov.io/github/saxix/django-strategy-field/coverage.svg?branch=develop
    :target: https://codecov.io/github/saxix/django-strategy-field?branch=develop

GitHub Stars

12

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1

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VersionTagPublished
1.2.0
8mos ago
1.1.0
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1.0.0
4yrs ago
0.1.0
5yrs ago
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