fcurella / Django Fakery
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Django-fakery
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An easy-to-use implementation of Creation Methods_ (aka Object Factory) for Django, backed by Faker.
.. _Creation Methods: http://xunitpatterns.com/Creation%20Method.html
django_fakery will try to guess the field's value based on the field's name and type.
Installation
Install with::
$ pip install django-fakery
QuickStart
.. code-block:: python
from django_fakery import factory
from myapp.models import MyModel
factory.m(MyModel)(field='value')
If you're having issues with circular imports, you can also reference a model by using the M utility function:
.. code-block:: python
from django_fakery import factory, M
factory.m(M("myapp.MyModel"))(field="value")
If you really don't want to import things, you could also just reference a model by using the <app_label>.<ModelName> syntax. This is not encouraged, as it will likely break type-hinting:
.. code-block:: python
from django_fakery import factory
factory.m("myapp.MyModel")(field="value")
If you use pytest, you can use the fakery fixture (requires pytest and pytest-django):
.. code-block:: python
import pytest
from myapp.models import MyModel
@pytest.mark.django_db
def test_mymodel(fakery):
fakery.m(MyModel)(field='value')
If you'd rather, you can use a more wordy API:
.. code-block:: python
from django_fakery import factory
from myapp.models import MyModel
factory.make(
MyModel,
fields={
'field': 'value',
}
)
We will use the short API thorough the documentation.
The value of a field can be any python object, a callable, or a lambda:
.. code-block:: python
from django.utils import timezone
from django_fakery import factory
from myapp.models import MyModel
factory.m(MyModel)(created=timezone.now)
When using a lambda, it will receive two arguments: n is the iteration number, and f is an instance of faker:
.. code-block:: python
from django.contrib.auth.models import User
user = factory.m(User)(
username=lambda n, f: 'user_{}'.format(n),
)
django-fakery includes some pre-built lambdas for common needs. See shortcuts_ for more info.
You can create multiple objects by using the quantity parameter:
.. code-block:: python
from django_fakery import factory
from django.contrib.auth.models import User
factory.m(User, quantity=4)
For convenience, when the value of a field is a string, it will be interpolated with the iteration number:
.. code-block:: python
from myapp.models import MyModel
user = factory.m(User, quantity=4)(
username='user_{}',
)
Foreign keys
Non-nullable ForeignKey s create related objects automatically.
If you want to explicitly create a related object, you can pass a factory like any other value:
.. code-block:: python
from django.contrib.auth.models import User
from food.models import Pizza
pizza = factory.m(Pizza)(
chef=factory.m(User)(username='Gusteau'),
)
If you'd rather not create related objects and reuse the same value for a foreign key, you can use the special value django_fakery.rels.SELECT:
.. code-block:: python
from django_fakery import factory, rels
from food.models import Pizza
pizza = factory.m(Pizza, quantity=5)(
chef=rels.SELECT,
)
django-fakery will always use the first instance of the related model, creating one if necessary.
ManyToManies
Because ManyToManyField s are implicitly nullable (ie: they're always allowed to have their .count() equal to 0), related objects on those fields are not automatically created for you.
If you want to explicitly create a related objects, you can pass a list as the field's value:
.. code-block:: python
from food.models import Pizza, Topping
pizza = factory.m(Pizza)(
toppings=[
factory.m(Topping)(name='Anchovies')
],
)
You can also pass a factory, to create multiple objects:
.. code-block:: python
from food.models import Pizza, Topping
pizza = factory.m(Pizza)(
toppings=factory.m(Topping, quantity=5),
)
.. _shortcuts:
Shortcuts
django-fakery includes some shortcut functions to generate commonly needed values.
future_datetime(end='+30d')
Returns a ``datetime`` object in the future (that is, 1 second from now) up to the specified ``end``. ``end`` can be a string, anotther datetime, or a timedelta. If it's a string, it must start with `+`, followed by and integer and a unit, Eg: ``'+30d'``. Defaults to ``'+30d'``
Valid units are:
* ``'years'``, ``'y'``
* ``'weeks'``, ``'w'``
* ``'days'``, ``'d'``
* ``'hours'``, ``'hours'``
* ``'minutes'``, ``'m'``
* ``'seconds'``, ``'s'``
Example:
.. code-block:: python
from django_fakery import factory, shortcuts
from myapp.models import MyModel
factory.m(MyModel)(field=shortcuts.future_datetime('+1w'))
``future_date(end='+30d')``
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Returns a ``date`` object in the future (that is, 1 day from now) up to the specified ``end``. ``end`` can be a string, another date, or a timedelta. If it's a string, it must start with `+`, followed by and integer and a unit, Eg: ``'+30d'``. Defaults to ``'+30d'``
``past_datetime(start='-30d')``
Returns a datetime object in the past between 1 second ago and the specified start. start can be a string, another datetime, or a timedelta. If it's a string, it must start with -, followed by and integer and a unit, Eg: '-30d'. Defaults to '-30d'
past_date(start='-30d')
Returns a ``date`` object in the past between 1 day ago and the specified ``start``. ``start`` can be a string, another date, or a timedelta. If it's a string, it must start with `-`, followed by and integer and a unit, Eg: ``'-30d'``. Defaults to ``'-30d'``
Lazies
------
You can refer to the created instance's own attributes or method by using `Lazy` objects.
For example, if you'd like to create user with email as username, and have them always match, you could do:
.. code-block:: python
from django_fakery import factory, Lazy
from django.contrib.auth.models import User
factory.m(auth.User)(
username=Lazy('email'),
)
If you want to assign a value returned by a method on the instance, you can pass the method's arguments to the ``Lazy`` object:
.. code-block:: python
from django_fakery import factory, Lazy
from myapp.models import MyModel
factory.m(MyModel)(
myfield=Lazy('model_method', 'argument', keyword='keyword value'),
)
Pre-save and Post-save hooks
----------------------------
You can define functions to be called right before the instance is saved or right after:
.. code-block:: python
from django.contrib.auth.models import User
from django_fakery import factory
factory.m(
User,
pre_save=[
lambda u: u.set_password('password')
],
)(username='username')
Since settings a user's password is such a common case, we special-cased that scenario, so you can just pass it as a field:
.. code-block:: python
from django.contrib.auth.models import User
from django_fakery import factory
factory.m(User)(
username='username',
password='password',
)
Get or Make
-----------
You can check for existance of a model instance and create it if necessary by using the ``g_m`` (short for ``get_or_make``) method:
.. code-block:: python
from myapp.models import MyModel
myinstance, created = factory.g_m(
MyModel,
lookup={
'myfield': 'myvalue',
}
)(myotherfield='somevalue')
If you're looking for a more explicit API, you can use the ``.get_or_make()`` method:
.. code-block:: python
from myapp.models import MyModel
myinstance, created = factory.get_or_make(
MyModel,
lookup={
'myfield': 'myvalue',
},
fields={
'myotherfield': 'somevalue',
},
)
Get or Update
-------------
You can check for existence of a model instance and update it by using the ``g_u`` (short for ``get_or_update``) method:
.. code-block:: python
from myapp.models import MyModel
myinstance, created = factory.g_u(
MyModel,
lookup={
'myfield': 'myvalue',
}
)(myotherfield='somevalue')
If you're looking for a more explicit API, you can use the ``.get_or_update()`` method:
.. code-block:: python
from myapp.models import MyModel
myinstance, created = factory.get_or_update(
MyModel,
lookup={
'myfield': 'myvalue',
},
fields={
'myotherfield': 'somevalue',
},
)
Non-persistent instances
------------------------
You can build instances that are not saved to the database by using the ``.b()`` method, just like you'd use ``.m()``:
.. code-block:: python
from django_fakery import factory
from myapp.models import MyModel
factory.b(MyModel)(
field='value',
)
Note that since the instance is not saved to the database, ``.build()`` does not support ManyToManies or post-save hooks.
If you're looking for a more explicit API, you can use the ``.build()`` method:
.. code-block:: python
from django_fakery import factory
from myapp.models import MyModel
factory.build(
MyModel,
fields={
'field': 'value',
}
)
Blueprints
----------
Use a blueprint:
.. code-block:: python
from django.contrib.auth.models import User
from django_fakery import factory
user = factory.blueprint(User)
user.make(quantity=10)
Blueprints can refer other blueprints:
.. code-block:: python
from food.models import Pizza
pizza = factory.blueprint(Pizza).fields(
chef=user,
)
)
You can also override the field values you previously specified:
.. code-block:: python
from food.models import Pizza
pizza = factory.blueprint(Pizza).fields(
chef=user,
thickness=1
)
)
pizza.m(quantity=10)(thickness=2)
Or, if you'd rather use the explicit api:
.. code-block:: python
from food.models import Pizza
pizza = factory.blueprint(Pizza).fields(
chef=user,
thickness=1
)
)
thicker_pizza = pizza.fields(thickness=2)
thicker_pizza.make(quantity=10)
Seeding the faker
-----------------
.. code-block:: python
from django.contrib.auth.models import User
from django_fakery import factory
factory.m(User, seed=1234, quantity=4)(
username='regularuser_{}'
)
Credits
-------
The API is heavily inspired by `model_mommy`_.
.. _model_mommy: https://github.com/vandersonmota/model_mommy
License
-------
This software is released under the MIT License.