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rsinger86
558 Stars 38 Forks MIT License 162 Commits 7 Opened issues

Description

Declarative model lifecycle hooks, an alternative to Signals.

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Django Lifecycle Hooks

Package version Python versions Python versions PyPI - Django Version

This project provides a

@hook
decorator as well as a base model and mixin to add lifecycle hooks to your Django models. Django's built-in approach to offering lifecycle hooks is Signals. However, my team often finds that Signals introduce unnecessary indirection and are at odds with Django's "fat models" approach.

Django Lifecycle Hooks supports Python 3.5, 3.6, 3.7 and 3.8, Django 2.0.x, 2.1.x, 2.2.x and 3.0.x.

In short, you can write model code like this:

from django_lifecycle import LifecycleModel, hook, BEFORE_UPDATE, AFTER_UPDATE


class Article(LifecycleModel): contents = models.TextField() updated_at = models.DateTimeField(null=True) status = models.ChoiceField(choices=['draft', 'published']) editor = models.ForeignKey(AuthUser)

@hook(BEFORE_UPDATE, when='contents', has_changed=True)
def on_content_change(self):
    self.updated_at = timezone.now()

@hook(AFTER_UPDATE, when="status", was="draft", is_now="published")
def on_publish(self):
    send_email(self.editor.email, "An article has published!")

Instead of overriding

save
and
__init__
in a clunky way that hurts readability:
    # same class and field declarations as above ...

def __init__(self, *args, **kwargs):
    super().__init__(*args, **kwargs)
    self._orig_contents = self.contents
    self._orig_status = self.status


def save(self, *args, **kwargs):
    if self.pk is not None and self.contents != self._orig_contents:
        self.updated_at = timezone.now()

    super().save(*args, **kwargs)

    if self.status != self._orig_status:
        send_email(self.editor.email, "An article has published!")


Documentation: https://rsinger86.github.io/django-lifecycle

Source Code: https://github.com/rsinger86/django-lifecycle


Changelog

0.8.0 (October 2020)

  • Significant performance improvements. Thanks @dralley!

0.7.7 (August 2020)

  • Fixes issue with
    GenericForeignKey
    . Thanks @bmbouter!

0.7.6 (May 2020)

  • Updates to use constants for hook names; updates docs to indicate Python 3.8/Django 3.x support. Thanks @thejoeejoee!

0.7.5 (April 2020)

  • Adds static typed variables for hook names; thanks @Faisal-Manzer!
  • Fixes some typos in docs; thanks @tomdyson and @bmispelon!

0.7.1 (January 2020)

  • Fixes bug in
    utils._get_field_names
    that could cause recursion bug in some cases.

0.7.0 (December 2019)

  • Adds
    changes_to
    condition - thanks @samitnuk! Also some typo fixes in docs.

0.6.1 (November 2019)

  • Remove variable type annotation for Python 3.5 compatability.

0.6.0 (October 2019)

  • Adds
    when_any
    hook parameter to watch multiple fields for state changes

0.5.0 (September 2019)

  • Adds
    was_not
    condition
  • Allow watching changes to FK model field values, not just FK references

0.4.2 (July 2019)

  • Fixes missing README.md issue that broke install.

0.4.1 (June 2019)

0.4.0 (May 2019)

  • Fixes
    initial_value(field_name)
    behavior - should return value even if no change. Thanks @adamJLev!

0.3.2 (February 2019)

  • Fixes bug preventing hooks from firing for custom PKs. Thanks @atugushev!

0.3.1 (August 2018)

  • Fixes m2m field bug, in which accessing auto-generated reverse field in
    before_create
    causes exception b/c PK does not exist yet. Thanks @garyd203!

0.3.0 (April 2018)

  • Resets model's comparison state for hook conditions after
    save
    called.

0.2.4 (April 2018)

  • Fixed support for adding multiple
    @hook
    decorators to same method.

0.2.3 (April 2018)

  • Removes residual mixin methods from earlier implementation.

0.2.2 (April 2018)

  • Save method now accepts
    skip_hooks
    , an optional boolean keyword argument that controls whether hooked methods are called.

0.2.1 (April 2018)

  • Fixed bug in
    _potentially_hooked_methods
    that caused unwanted side effects by accessing model instance methods decorated with
    @cache_property
    or
    @property
    .

0.2.0 (April 2018)

  • Added Django 1.8 support. Thanks @jtiai!
  • Tox testing added for Python 3.4, 3.5, 3.6 and Django 1.8, 1.11 and 2.0. Thanks @jtiai!

Testing

Tests are found in a simplified Django project in the

/tests
folder. Install the project requirements and do
./manage.py test
to run them.

License

See License.

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