A model instances generator for Django
Project description
An easy-to-use implementation of Creation Methods (aka Object Factory) for Django, backed by Faker.
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
from django_fakery import factory
factory.m('app.Model')(field='value')Alternatively, you can use a more explicit API:
from django_fakery import factory
factory.make(
'app.Model',
fields={
'field': 'value',
}
)We will use the short API throught the documentation.
The value of a field can be any python object, a callable, or a lambda:
from django_fakery import factory
from django.utils import timezone
factory.m('app.Model')(created=timezone.now)When using a lambda, it will receive two arguments: n is the iteration number, and f is an instance of faker:
user = factory.m('auth.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:
from django_fakery import factory
factory.m('app.Model', quantity=4)For convenience, when the value of a field is a string, it will be interpolated with the iteration number:
user = factory.m('auth.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:
pizza = factory.m('food.Pizza')(
chef=factory.m('auth.User)(username='Gusteau'),
)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:
pizza = factory.m('food.Pizza')(
toppings=[
factory.m('food.Topping')(name='Anchovies')
],
)You can also pass a factory, to create multiple objects:
pizza = factory.m('food.Pizza')(
toppings=factory.m('food.Topping', quantity=5),
)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:
from django_fakery import factory, shortcuts
factory.m('app.Model')(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:
from django_fakery import factory, Lazy
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:
from django_fakery import factory, Lazy
factory.m('myapp.Model')(
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:
from django_fakery import factory
factory.m(
'auth.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:
from django_fakery import factory
factory.m('auth.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:
myinstance, created = factory.g_m(
'myapp.Model',
lookup={
'myfield': 'myvalue',
}
)(myotherfield='somevalue')If you’re looking for a more explicit API, you can use the .get_or_make() method:
myinstance, created = factory.get_or_make(
'myapp.Model',
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:
myinstance, created = factory.g_u(
'myapp.Model',
lookup={
'myfield': 'myvalue',
}
)(myotherfield='somevalue')If you’re looking for a more explicit API, you can use the .get_or_update() method:
myinstance, created = factory.get_or_update(
'myapp.Model',
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():
from django_fakery import factory
factory.b('app.Model')(
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:
from django_fakery import factory
factory.build(
'app.Model',
fields={
'field': 'value',
}
)Blueprints
Use a blueprint:
from django_fakery import factory
user = factory.blueprint('auth.User')
user.make(quantity=10)Blueprints can refer other blueprints:
pizza = factory.blueprint('food.Pizza').fields(
chef=user,
)
)You can also override the field values you previously specified:
pizza = factory.blueprint('food.Pizza').fields(
chef=user,
thickness=1
)
)
pizza.m(quantity=10)(thickness=2)Or, if you’d rather use the explicit api:
pizza = factory.blueprint('food.Pizza').fields(
chef=user,
thickness=1
)
)
thicker_pizza = pizza.fields(thickness=2)
thicker_pizza.make(quantity=10)Seeding the faker
from django_fakery import factory
factory.m('auth.User', seed=1234, quantity=4)(
username='regularuser_{}'
)Credits
The API is heavily inspired by model_mommy.
License
This software is released under the MIT License.
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