django-behaviors 0.3.0

=============================
Django Behaviors
=============================

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Common behaviors for Django Models, e.g. Timestamps, Publishing, Authoring/Editing and more.

Inspired by Kevin Stone's `Django Model Behaviors`_.

Documentation
=============

Quickstart
----------

Install Django Behaviors::

pip install django-behaviors

Add it to your `INSTALLED_APPS`:

.. code-block:: python

INSTALLED_APPS = (
...
'behaviors.apps.BehaviorsConfig',
...
)

Features
--------

``behaviors`` makes it easy to integrate common behaviors into your django models:

- **Documented**, **tested**, and **easy to use**
- **Timestamped** to add ``created`` and ``modified`` attributes to your models
- **Authored** to add an ``author`` to your models
- **Editored** to add an ``editor`` to your models
- **Published** to add a ``publication_status`` (draft or published) to your models
- **Released** to add a ``release_date`` to your models
- **Slugged** to add a ``slug`` to your models (thanks @apirobot)
- Easily compose together multiple ``behaviors`` to get desired functionality (e.g. ``Authored`` and ``Editored``)
- Custom ``QuerySet`` methods added as managers to your models to utilize the added fields
- Easily compose together multiple ``queryset`` or ``manager`` to get desired functionality

Table of Contents
-----------------

- `Behaviors`_
- `Timestamped`_
- `Authored`_
- `Editored`_
- `Published`_
- `Released`_
- `Slugged`_
- `Mixing in with Custom Managers`_
- `Mixing Multiple Behaviors`_

Behaviors
---------

Timestamped Behavior
``````````````````````

The model adds a ``created`` and ``modified`` field to your model.

.. code-block:: python

class Timestamped(models.Model):
"""
An abstract behavior representing timestamping a model with``created`` and
``modified`` fields.
"""
created = models.DateTimeField(auto_now_add=True, db_index=True)
modified = models.DateTimeField(null=True, blank=True)

class Meta:
abstract = True

@property
def changed(self):
return True if self.modified else False

def save(self, *args, **kwargs):
if self.pk:
self.modified = timezone.now()
return super(Timestamped, self).save(*args, **kwargs)

``created`` is set on the next save and is set to the current UTC time.
``modified`` is set when the object already exists and is set to the current UTC time.

``MyModel.changed`` returns a boolean representing if the object has been updated after created (the ``modified`` field has been set).

Here is an example of using the model, note you do not need to add ``models.Model`` because ``Timestamped`` already inherits it.

.. code-block:: python

# models.py
from behaviors.behaviors import Authored, Editored, Timestamped, Published


class MyModel(Timestamped):
name = models.CharField(max_length=100)


>>> m = MyModel.objects.create(name='dj')
>>> m.created
'2017-02-14 17:20:19.835517+00:00'
>>> m.modified
None
>>> m.changed
False
>>> m.save()
>>> m.modified
'2017-02-14 17:20:46.836395+00:00'
>>> m.changed
True

Authored Behavior
``````````````````

The authored model adds an ``author`` attribute that is a foreign key to the ``settings.AUTH_USER_MODEL`` and adds manager methods through ``objects`` and ``authors``.

.. code-block:: python

class Authored(models.Model):
"""
An abstract behavior representing adding an author to a model based on the
AUTH_USER_MODEL setting.
"""
author = models.ForeignKey(
settings.AUTH_USER_MODEL,
related_name="%(app_label)s_%(class)s_author")

objects = AuthoredQuerySet.as_manager()
authors = AuthoredQuerySet.as_manager()

class Meta:
abstract = True

Here is an example of using the behavior and its ``authored_by()`` manager method:

.. code-block:: python

# models.py
from behaviors.behaviors import Authored


class MyModel(Authored):
name = models.CharField(max_length=100)

>>> m = MyModel.objects.create(author=User.objects.get(pk=2), name='tj')
>>> m.author
<User: ...>
>>> queryset = MyModel.objects.authored_by(User.objects.get(pk=2))
>>> queryset.count()
1

The author is a required field and must be provided on initial ``POST`` requests that create an object.

A custom ``models.ModelForm`` is provided to automatically add the ``author``
on object creation:

.. code-block:: python

# forms.py
from behaviors.forms import AuthoredModelForm
from .models import MyModel


class MyModelForm(AuthoredModelForm):
class Meta:
model = MyModel
fields = ['name']

# views.py
from django.views.generic.edit import CreateView
from .forms import MyModelForm
from .models import MyModel


class MyModelCreateView(CreateView):
model = MyModel
form = MyModelForm

# add request to form kwargs
def get_form_kwargs(self):
kwargs = super(MyModelCreateView, self).get_form_kwargs()
kwargs['request'] = self.request
return kwargs

Now when the object is created the ``author`` will be added on the call
to ``form.save()``.

If you are using functional views or another view type you simply need
to make sure you pass the request object along with the form.

.. code-block:: python
# views.py

class MyModelView(View):
template_name = "myapp/mymodel_form.html"

def get(self, request, *args, **kwargs):
context = {
'form': MyModelForm(),
}
return render(request, self.template_name, context=context)

def post(self, request, *args, **kwargs):
# pass in request object to the request keyword argument
form = MyModelForm(self.request.POST, request=request)
if form.is_valid():
form.save()
return reverse(..)
context = {
'form': form,
}
return render(request, self.template_name, context=context)

If for some reason you don't want to mixin the ``AuthoredModelForm`` with your existing
form you can just add the user like so:

.. code-block:: python
...
if form.is_valid()
obj = form.save(commit=False)
obj.author = request.user
obj.save()
return reverse(..)
...

But it isn't recommended, the ``AuthoredModelForm`` is tested and doesn't reassign the
author on every save.

The ``related_name`` is set so that it will never create conflicts. Given the above example if you wanted to do a reverse foreign key lookup from the User model and ``MyModel`` was part of the ``blogs`` app it could be done like so:

.. code-block:: python
>>> user = User.objects.get(pk=2)
>>> user.blogs_mymodel_author.all()
[<MyModel: ...>]

That would give a list of all ``MyModel`` objects that ``user`` has ``authored``.

Authored QuerySet
..................

The ``Authored`` behavior attaches a custom model manager to the default ``objects``
and to the ``authors`` variables on the model it is mixed into. If you haven't overrode
the ``objects`` variable with a custom manager then you can use that, otherwise the
``authors`` variable is a fallback.

To get all ``MyModel`` instances authored by people whose name starts with 'Jo'

.. code-block:: python

# case is insensitive so 'joe' or 'Joe' matches
>>> MyModel.objects.authored_by('Jo')
[<MyModel: ...>, <MyModel: ...>, ...]

# or use the authors manager variable
>>> MyModel.authors.authored_by('Jo')
[<MyModel: ...>, <MyModel: ...>, ...]

See `Mixing in with Custom Managers`_ for details on how
to mix in this behavior with a custom manager you have that overrides the ``objects``
default manager.


Editored Behavior
``````````````````

The editored model adds an ``editor`` attribute that is a foreign key to the ``settings.AUTH_USER_MODEL`` and adds manager methods through ``objects`` and ``editors`` variables.


.. code-block:: python

class Editored(models.Model):
"""
An abstract behavior representing adding an editor to a model based on the
AUTH_USER_MODEL setting.
"""
editor = models.ForeignKey(
settings.AUTH_USER_MODEL,
related_name="%(app_label)s_%(class)s_editor",
blank=True, null=True)

objects = EditoredQuerySet.as_manager()
editors = EditoredQuerySet.as_manager()

class Meta:
abstract = True

The ``Editored`` model is similar to the ``Authored`` model except the foreign key is **not required**. Here is an example of its usage:

.. code-block:: python

# models.py
from behaviors.behaviors import Editored


class MyModel(Editored):
name = models.CharField(max_length=100)

>>> m = MyModel.objects.create(name='pj')
>>> m.editor
None
>>> m.editor = User.objects.all()[0]
>>> m.save()
>>> queryset = MyModel.objects.edited_by(User.objects.all()[0])
>>> queryset.count()
1

By default the ``editor`` is blank and null, if a ``request`` object is supplied to the form it will assign a new editor and erase the previous editor (or the null editor).

Instead of using the ``AuthoredModelForm`` use the ``EditoredModelForm`` as a mixin to
your form.

.. code-block:: python

# forms.py
from behaviors.forms import EditoredModelForm
from .models import MyModel


class MyModelForm(EditoredModelForm):
class Meta:
model = MyModel
fields = ['name']

# views.py
from django.views.generic.edit import CreateView, UpdateView
from .forms import MyModelForm
from .models import MyModel


MyModelRequestFormMixin(object):
# add request to form kwargs
def get_form_kwargs(self):
kwargs = super(MyModelCreateView, self).get_form_kwargs()
kwargs['request'] = self.request
return kwargs


class MyModelCreateView(MyModelRequestFormMixin, CreateView):
model = MyModel
form = MyModelForm


class MyModelUpdateView(MyModelRequestFormMixin, UpdateView):
model = MyModel
form = MyModelForm


Now when the object is created or updated the ``editor`` will be updated
on the call to ``form.save()``.

If you are using functional views or another view type you simply need
to make sure you pass the request object along with the form.

.. code-block:: python

# views.py

class MyModelView(View):
template_name = "myapp/mymodel_form.html"

def get(self, request, *args, **kwargs):
context = {
'form': MyModelForm(),
}
return render(request, self.template_name, context=context)

def post(self, request, *args, **kwargs):
# pass in request object to the request keyword argument
form = MyModelForm(self.request.POST, request=request)
if form.is_valid():
form.save()
return reverse(..)
context = {
'form': form,
}
return render(request, self.template_name, context=context)

If for some reason you don't want to mixin the ``EditoredModelForm`` with your existing
form you can just add the user like so:

.. code-block:: python

...
if form.is_valid()
obj = form.save(commit=False)
obj.editor = request.user
obj.save()
return reverse(..)
...

But it isn't recommended, the ``EditoredModelForm`` is tested and doesn't cause errors
if request.user is invalid.

The ``related_name`` is set so that it will never create conflicts. Given the above example if you wanted to do a reverse foreign key lookup from the User model and ``MyModel`` was part of the ``blogs`` app it could be done like so:

.. code-block:: python

>>> user = User.objects.get(pk=2)
>>> user.blogs_mymodel_editor.all()
[<MyModel: ...>]

That would give a list of all ``MyModel`` objects that ``user`` is an ``editor``.

Editored QuerySet
..................

The ``Editored`` behavior attaches a custom model manager to the default ``objects``
and to the ``editors`` variables on the model it is mixed into. If you haven't overrode
the ``objects`` variable with a custom manager then you can use that, otherwise the
``editors`` variable is a fallback.

To get all ``MyModel`` instances edited by people whose name starts with 'Jo'

.. code-block:: python

# case is insensitive so 'joe' or 'Joe' matches
>>> MyModel.objects.edited_by('Jo')
[<MyModel: ...>, <MyModel: ...>, ...]

# or use the editors manager variable
>>> MyModel.editors.edited_by('Jo')
[<MyModel: ...>, <MyModel: ...>, ...]

See `Mixing in with Custom Managers`_ for details on how
to mix in this behavior with a custom manager you have that overrides the ``objects``
default manager.

Published Behavior
````````````````````

The ``Published`` behavior adds a field ``publication_status`` to your model. The status
has two states: 'Draft' or 'Published'.

.. code-block:: python

class Published(models.Model):
"""
An abstract behavior representing adding a publication status. A
``publication_status`` is set on the model with Draft or Published
options.
"""
DRAFT = 'd'
PUBLISHED = 'p'

PUBLICATION_STATUS_CHOICES = (
(DRAFT, 'Draft'),
(PUBLISHED, 'Published'),
)

publication_status = models.CharField(
"Publication Status", max_length=1,
choices=PUBLICATION_STATUS_CHOICES, default=DRAFT)

class Meta:
abstract = True

objects = PublishedQuerySet.as_manager()
publications = PublishedQuerySet.as_manager()

@property
def draft(self):
return self.publication_status == self.DRAFT

@property
def published(self):
return self.publication_status == self.PUBLISHED

The class offers two properties ``draft`` and ``published`` to know object state. The ``DRAFT`` and ``PUBLISHED`` class constants will be available from the class the ``Published`` behavior is mixed into. There is also a custom manager attached to ``objects`` and ``publications`` variables to get ``published()`` or ``draft()`` querysets.

.. code-block:: python

# models.py
from behaviors.behaviors import Published


class MyModel(Published):
name = models.CharField(max_length=100)

>>> m = MyModel.objects.create(name='cj')
>>> m.publication_status
u'd'
>>> m.draft
True
>>> m.published
False
>>> m.get_publication_status_display()
u'Draft'
>>> MyModel.objects.published().count()
0
>>> MyModel.objects.draft().count()
1
>>> m.publication_status = MyModel.PUBLISHED
>>> m.save()
>>> m.publication_status
u'p'
>>> m.draft
False
>>> m.published
True
>>> m.get_publication_status_display()
u'Published'
>>> MyModel.objects.published().count()
1
>>> MyModel.PUBLISHED
u'p'
>>> MyModel.PUBLISHED == m.publication_status
True

The ``publication_status`` field defaults to ``Published.DRAFT`` when you make new
models unless you supply the ``Published.PUBLISHED`` attribute to the ``publication_status``
field.

.. code-block:: python

MyModel.objects.create(name='Jim-bob Cooter', publication_status=MyModel.PUBLISHED)

Published QuerySet
...................

The ``Published`` behavior attaches to the default ``objects`` variable and
the ``publications`` variable as a fallback if ``objects`` is overrode.

.. code-block:: python

# returns all MyModel.PUBLISHED
MyModel.objects.published()
MyModel.publications.published()

# returns all MyModel.DRAFT
MyModel.objects.draft()
MyModel.publications.draft()


Released Behavior
``````````````````

The ``Released`` behavior adds a field ``release_date`` to your model. The field
is **not_required**. The release date can be set with the ``release_on(datetime)`` method.

.. code-block:: python

class Released(models.Model):
"""
An abstract behavior representing a release_date for a model to
indicate when it should be listed publically.
"""
release_date = models.DateTimeField(null=True, blank=True)

class Meta:
abstract = True

objects = ReleasedQuerySet.as_manager()
releases = ReleasedQuerySet.as_manager()

def release_on(self, date=None):
if not date:
date = timezone.now()
self.release_date = date
self.save()

@property
def released(self):
return self.release_date and self.release_date < timezone.now()

There is a ``released`` property added which determines if the object has been released. There is a custom manager attached to ``objects`` and ``releases`` variables to filter querysets on their release date.

Here is an example of using the behavior:

.. code-block:: python

# models.py
from django.utils import timezone
from datetime import timedelta
from behaviors.behaviors import Released


class MyModel(Released):
name = models.CharField(max_length=100)

>>> m = MyModel.objects.create(name='rj')
>>> m.release_date
None
>>> MyModel.objects.no_release_date().count()
1
>>> m.release_on()
>>> MyModel.objects.no_release_date().count()
0
>>> MyModel.objects.released().count()
1
>>> m.release_on(timezone.now() + timedelta(weeks=1))
>>> MyModel.objects.not_released().count()
1
>>> MyModel.objects.released().count()
0

The ``release_on`` method defaults to the current time so that the object is immediately
released. You can also provide a date to the method to release on a certain date. ``release_on()`` just serves as a wrapper to setting and saving the date.

You can always provide a ``release_date`` on object creation:

.. code-block:: python

MyModel.objects.create(name='Jim-bob Cooter', release_date=timezone.now())


Released QuerySet
...................

The ``Released`` behavior attaches to the default ``objects`` variable and
the ``releases`` variable as a fallback if ``objects`` is overrode.

.. code-block:: python

# returns all not released MyModel objects
MyModel.objects.not_released()
MyModel.releases.not_released()

# returns all released MyModel objects
MyModel.objects.released()
MyModel.releases.released()

# returns all null release date MyModel objects
MyModel.objects.no_release_date()
MyModel.releases.no_release_date()

Slugged Behavior
``````````````````

The ``Slugged`` behavior allows you to easily add a ``slug`` field to your model. The slug is generated on the first model creation or the next model save and is based on the ``slug_source`` attribute.

**The** ``slug_source`` **property has no set default, you must add it to your model for the behavior to work.**

.. code-block:: python

class Slugged(models.Model):
"""
An abstract behavior representing adding a unique slug to a model
based on the slug_source property.
"""
slug = models.SlugField(max_length=255, unique=True)

class Meta:
abstract = True

def save(self, *args, **kwargs):
if not self.slug:
self.slug = self.generate_unique_slug()
super(Slugged, self).save(*args, **kwargs)

def get_slug(self):
return slugify(getattr(self, "slug_source"), to_lower=True)

def is_unique_slug(self, slug):
qs = self.__class__.objects.filter(slug=slug)
return not qs.exists()

def generate_unique_slug(self):
slug = self.get_slug()
new_slug = slug

iteration = 1
while not self.is_unique_slug(new_slug):
new_slug = "%s-%d" % (slug, iteration)
iteration += 1

return new_slug

The ``slug`` uses the awesome-slugify package which will preserve unicode character slugs. The ``slug`` must be unique and is guaranteed to be unique by the class appending a number ``-[0-9+]`` to the end of the slug if it is not unique. The ``unique`` field type `adds an index`_ to the ``slug`` field.

Add the ``slug_source`` property to your class when mixing in the behavior.

.. code-block:: python

# models.py
from behaviors.behaviors import Slugged


class MyModel(Slugged):
name = models.CharField(max_length=100)

# slug_source is required for the slug to be set
@property
def slug_source(self):
return "prepended-text-for-fun-{}".format(self.name)

# you can now use the slug for your get_absolute_url() method
def get_absolute_url(self):
return reverse('myapp:mymodel_detail', args=[self.slug])

>>> m = MyModel.objects.create(name='aj')
>>> m.slug
'prepended-text-for-fun-aj'
>>> m2 = MyModel.objects.create(name='aj')
>>> m.slug
'prepended-text-for-fun-aj-1'
>>> m.get_absolute_url()
'/myapp/prepended-text-for-fun-aj/detail'

Your ``slug_source`` attribute can be a mix of any of the model data available at the time of save, generally it is some ``name`` type of field. You could also hash the primary key and/or some other data as a ``slug_source``. The ``slug`` is unique so it can be used to define the ``get_absolute_url()`` method on your model.

Thanks to @apirobot for sending the PR for the ``Slugged`` behavior.

Mixing in with Custom Managers
------------------------------

If you have a custom manager on your model already:

.. code-block:: python

# models.py
from behaviors.behaviors import Authored, Editored, Published, Timestamped

from django.db import models


class MyModelCustomManager(models.Manager):

def get_queryset(self):
return super(MyModelCustomManager).get_queryset(self)

def custom_manager_method(self):
return self.get_queryset().filter(name='Jim-bob')

class MyModel(Authored):
name = models.CharField(max_length=100)

# MyModel.objects.authored_by(..) won't work
# MyModel.authors.authored_by(..) still will
objects = MyModelCustomManager()

Simply add ``AuthoredManager`` from ``behaviors.managers`` as a mixin to
``MyModelCustomManager`` so they can share the ``objects`` variable.

.. code-block:: python

# models.py
from behaviors.behaviors import Authored, Editored, Published, Timestamped
from behaviors.managers import AuthoredManager, EditoredManager, PublishedManager

from django.db import models


class MyModelCustomManager(AuthoredManager, models.Manager):

def get_queryset(self):
return super(MyModelCustomManager).get_queryset(self)

def custom_manager_method(self):
return self.get_queryset().filter(name='Jim-bob')

class MyModel(Authored):
name = models.CharField(max_length=100)

# MyModel.objects.authored_by(..) now works
objects = MyModelCustomManager()

Similarly if you are using a custom QuerySet and calling its ``as_manager()``
method to attach it to ``objects`` you can import from ``behaviors.querysets``
and mix it in.

.. code-block:: python

# models.py
from behaviors.behaviors import Authored, Editored, Published, Timestamped
from behaviors.querysets import AuthoredQuerySet, EditoredQuerySet, PublishedQuerySet

from django.db import models


class MyModelCustomQuerySet(AuthoredQuerySet, models.QuerySet):

def custom_queryset_method(self):
return self.filter(name='Jim-bob')

class MyModel(Authored):
name = models.CharField(max_length=100)

# MyModel.objects.authored_by(..) works
objects = MyModelCustomQuerySet.as_manager()


Mixing in Multiple Behaviors
----------------------------

Many times you will want multiple behaviors on a model. You can simply mix in
multiple behaviors and, if you'd like to have all their custom ``QuerySet``
methods work on ``objects``, provide a custom manager with all the mixins.

.. code-block:: python

# models.py
from behaviors.behaviors import Authored, Editored, Published, Timestamped
from behaviors.querysets import AuthoredQuerySet, EditoredQuerySet, PublishedQuerySet

from django.db import models


class MyModelQuerySet(AuthoredQuerySet, EditoredQuerySet, PublishedQuerySet):
pass

class MyModel(Authored, Editored, Published, Timestamped):
name = models.CharField(max_length=100)

# MyModel.objects.authored_by(..) works
# MyModel.objects.edited_by(..) works
# MyModel.objects.published() works
# MyModel.objects.draft() works
objects = MyModelQuerySet.as_manager()

# you can also chain queryset methods
>>> u = User.objects.all()[0]
>>> u2 = User.objects.all()[1]
>>> m = MyModel.objects.create(author=u, editor=u2)
>>> MyModel.objects.published().authored_by(u).count()
1


Running Tests
-------------

Does the code actually work?

::

source <YOURVIRTUALENV>/bin/activate
(myenv) $ pip install tox
(myenv) $ tox

Credits
-------

Tools used in rendering this package:

* Cookiecutter_
* `cookiecutter-djangopackage`_

.. _Cookiecutter: https://github.com/audreyr/cookiecutter
.. _`cookiecutter-djangopackage`: https://github.com/pydanny/cookiecutter-djangopackage

.. _`Timestamped`: #timestamped-behavior
.. _`Authored`: #authored-behavior
.. _`Editored`: #editored-behavior
.. _`Published`: #published-behavior
.. _`Released`: #released-behavior
.. _`Slugged`: #slugged-behavior
.. _`settings.AUTH_USER_MODEL`: https://docs.djangoproject.com/en/1.10/ref/settings/#std:setting-AUTH_USER_MODEL
.. _`Mixing in with Custom Managers`: #mixing-in-with-custom-managers
.. _`Mixing Multiple Behaviors`: #mixing-in-multiple-behaviors
.. _`Django Model Behaviors`: http://blog.kevinastone.com/django-model-behaviors.html
.. _`adds an index`: https://docs.djangoproject.com/en/dev/ref/models/fields/#unique




History
-------

0.3.0 (2017-03-11)
++++++++++++++++++

* Add ``Slugged`` behavior adding a slug to models
* Update documentation

0.2.0 (2017-02-14)
++++++++++++++++++

* Add ``Released`` behavior for a release date on models
* Update documentation

0.1.7 (2017-02-14)
++++++++++++++++++

* Remove an unused import
* Integrate with Lintly

0.1.6 (2017-02-14)
++++++++++++++++++

* Drop python3.3 support for Django 1.8 because 1.8 no longer supports it

0.1.5 (2017-02-14)
++++++++++++++++++

* Fix import error for py2.7 builds

0.1.4 (2017-02-14)
++++++++++++++++++

* Fix Syntax Error

0.1.3 (2017-02-14)
++++++++++++++++++

* Fixed Circular Import

0.1.2 (2017-02-13)
++++++++++++++++++

* Travis CI Fixes

0.1.1 (2017-02-13)
++++++++++++++++++

* First release on PyPI
* Flake8 adherence fixes

0.1.0 (2017-02-13)
++++++++++++++++++

* First push of project