Model Mommy: Smart fixtures for better tests¶
Model-mommy offers you a smart way to create fixtures for testing in Django. With a simple and powerful API you can create many objects with a single line of code.
Contributing to Model Mommy¶
As an open source project, Model Mommy welcomes contributions of many forms
Examples of contributions include:
- Code Patches
- Documentation improvements
- Bug reports
Contributing¶
- Prepare a virtual environment.
pip install virtualenvwrapper
mkvirtualenv model_mommy --no-site-packages --distribute
- Install the requirements.
pip install -r dev_requirements.txt
- Run the tests.
make test
Inspiration¶
Model-mommy was inspired by many great open source software like ruby’s ObjectDaddy and FactoryGirl.
Doubts? Loved it? Hated it? Suggestions?¶
Join our mailing list for support, development and ideas!
Contents:
Basic Usage¶
Let’s say you have an app family with a model like this:
File: model.py
class Kid(models.Model):
"""
Model class Kid of family app
"""
happy = models.BooleanField()
name = models.CharField(max_length=30)
age = models.IntegerField()
bio = models.TextField()
wanted_games_qtd = models.BigIntegerField()
birthday = models.DateField()
appointment = models.DateTimeField()
To create a persisted instance, just call Mommy:
File: test_model.py
# -*- coding:utf-8 -*-
#Core Django imports
from django.test import TestCase
#Third-party app imports
from model_mommy import mommy
from model_mommy.recipe import Recipe, foreign_key
# Relative imports of the 'app-name' package
from .models import Kid
class KidTestModel(TestCase):
"""
Class to test the model
Kid
"""
def setUp(self):
"""
Set up all the tests
"""
self.kid = mommy.make(Kid)
No need to pass attributes every damn time.
Importing every model over and over again is boring. So let Mommy import them for you:
from model_mommy import mommy
# 1st form: app_label.model_name
kid = mommy.make('family.Kid')
# 2nd form: model_name
dog = mommy.make('Dog')
Note
You can only use the 2nd form on unique model names. If you have an app family with a Dog, and an app farm with a Dog, you must use the app_label.model_name form.
Note
model_name is case insensitive.
Model Relationships¶
Mommy also handles relationships. Say the kid has a dog:
File: model.py
class Kid(models.Model):
"""
Model class Kid of family app
"""
happy = models.BooleanField()
name = models.CharField(max_length=30)
age = models.IntegerField()
bio = models.TextField()
wanted_games_qtd = models.BigIntegerField()
birthday = models.DateField()
appointment = models.DateTimeField()
class Meta:
verbose_name = _(u'Kid')
verbose_name_plural = _(u'Kids')
def __unicode__(self):
"""
Return the name of kid
"""
return u'%s' % (self.name)
class Dog(models.Model):
"""
Model class Dog of family app
"""
owner = models.ForeignKey('Kid')
when you ask Mommy:
File: test_model.py
# -*- coding:utf-8 -*-
#Core Django imports
from django.test import TestCase
#Third-party app imports
from model_mommy import mommy
from model_mommy.recipe import Recipe, foreign_key
# Relative imports of the 'app-name' package
class DogTestModel(TestCase):
"""
Class to test the model
Dog
"""
def setUp(self):
"""
Set up all the tests
"""
self.rex = mommy.make('family.Dog')
She will also create the Kid, automagically. NOTE: ForeignKeys and OneToOneFields Since Django 1.8, ForeignKey and OneToOne fields don’t accept unpersisted model instances anymore. This means if you do:
mommy.prepare(‘family.Dog’)
You’ll end with a persisted “Kid” instance.
M2M Relationships¶
File: test_model.py
# -*- coding:utf-8 -*-
#Core Django imports
from django.test import TestCase
#Third-party app imports
from model_mommy import mommy
from model_mommy.recipe import Recipe, foreign_key
# Relative imports of the 'app-name' package
class DogTestModel(TestCase):
"""
Class to test the model
Dog
"""
def setUp(self):
"""
Set up all the tests
"""
self.rex = mommy.make('family.Dog', make_m2m=True)
Defining some attributes¶
Of course it’s possible to explicitly set values for attributes.
File: test_model.py
# -*- coding:utf-8 -*-
#Core Django imports
from django.test import TestCase
#Third-party app imports
from model_mommy import mommy
from model_mommy.recipe import Recipe, foreign_key
# Relative imports of the 'app-name' package
from .models import Kid
class KidTestModel(TestCase):
"""
Class to test the model
Kid
"""
def setUp(self):
"""
Set up all the tests
"""
self.kid = mommy.make(
Kid,
age=3
)
self.another_kid = mommy.make(
'family.Kid',
age=6
)
Related objects attributes are also reachable by their name or related names:
File: test_model.py
# -*- coding:utf-8 -*-
#Core Django imports
from django.test import TestCase
#Third-party app imports
from model_mommy import mommy
from model_mommy.recipe import Recipe, foreign_key
# Relative imports of the 'app-name' package
from .models import Dog
class DogTestModel(TestCase):
"""
Class to test the model
Dog
"""
def setUp(self):
"""
Set up all the tests
"""
self.bobs_dog = mommy.make(
'family.Dog',
owner__name='Bob'
)
Non persistent objects¶
If you don’t need a persisted object, Mommy can handle this for you as well:
from model_mommy import mommy
kid = mommy.prepare('family.Kid')
It works like make, but it doesn’t persist the instance neither the related instances.
If you want to persist only the related instances but not your model, you can use the _save_related parameter for it:
from model_mommy import mommy
dog = mommy.prepare('family.Dog', _save_related=True)
assert dog.id is None
assert bool(dog.owner.id) is True
More than one instance¶
If you need to create more than one instance of the model, you can use the _quantity parameter for it:
from model_mommy import mommy
kids = mommy.make('family.Kid', _quantity=3)
assert len(kids) == 3
It also works with prepare:
from model_mommy import mommy
kids = mommy.prepare('family.Kid', _quantity=3)
assert len(kids) == 3
How mommy behaves?¶
By default, model-mommy skips fields with null=True or blank=True. Also if a field has a default value, it will be used.
You can override this behavior by:
- Explicitly defining values
# from "Basic Usage" page, assume all fields either null=True or blank=True
from .models import Kid
from model_mommy import mommy
kid = mommy.make(Kid, happy=True, bio='Happy kid')
- Passing _fill_optional with a list of fields to fill with random data
kid = mommy.make(Kid, _fill_optional=['happy', 'bio'])
- Passing _fill_optional=True to fill all fields with random data
kid = mommy.make(Kid, _fill_optional=True)
When shouldn’t you let mommy generate things for you?¶
If you have fields with special validation, you should set their values by yourself.
Model-mommy should handle fields that:
- don’t matter for the test you’re writing;
- don’t require special validation (like unique, etc);
- are required to create the object.
Currently supported fields¶
- BooleanField, IntegerField, BigIntegerField, SmallIntegerField, PositiveIntegerField, PositiveSmallIntegerField, FloatField, DecimalField
- CharField, TextField, BinaryField, SlugField, URLField, EmailField, IPAddressField, GenericIPAddressField
- ForeignKey, OneToOneField, ManyToManyField (even with through model)
- DateField, DateTimeField, TimeField
- FileField, ImageField
- JSONField, ArrayField, HStoreField
Custom fields¶
Model-mommy allows you to define generators methods for your custom fields or overrides its default generators. This could be achieved by specifing the field and generator function for the generators.add function. Both can be the real python objects imported in settings or just specified as import path string.
Examples:
from model_mommy import mommy
def gen_func():
return 'value'
mommy.generators.add('test.generic.fields.CustomField', gen_func)
# in the module code.path:
def gen_func():
return 'value'
# in your tests.py file:
from model_mommy import mommy
mommy.generatos.add('test.generic.fields.CustomField', 'code.path.gen_func')
Customizing Mommy¶
In some rare cases, you might need to customize the way Mommy behaves. This can be achieved by creating a new class and specifying it in your settings files. It is likely that you will want to extend Mommy, however the minimum requirement is that the custom class have make and prepare functions. In order for the custom class to be used, make sure to use the model_mommy.mommy.make and model_mommy.mommy.prepare functions, and not model_mommy.mommy.Mommy directly.
Examples:
# in the module code.path:
class CustomMommy(mommy.Mommy)
def get_fields(self):
return [
field
for field in super(CustomMommy, self).get_fields()
if not field isinstance CustomField
]
# in your settings.py file:
MOMMY_CUSTOM_CLASS = 'code.path.CustomMommy'
Save method custom parameters¶
If you have overwritten the save method for a model, you can pass custom parameters to it using model mommy. Example:
class ProjectWithCustomSave(models.Model)
# some model fields
created_by = models.ForeignKey(settings.AUTH_USER_MODEL)
def save(self, user, *args, **kwargs):
self.created_by = user
return super(ProjectWithCustomSave, self).save(*args, **kwargs)
#with model mommy:
user = mommy.make(settings.AUTH_USER_MODEL)
project = mommy.make(ProjectWithCustomSave, _save_kwargs={'user': user})
assert user == project.user
Recipes¶
If you’re not comfortable with random data or even you just want to improve the semantics of the generated data, there’s hope for you.
You can define a recipe, which is a set of rules to generate data for your models. Create a module called mommy_recipes.py at your app’s root directory:
fixtures/
migrations/
templates/
tests/
__init__.py
admin.py
managers.py
models.py
mommy_recipes.py
urls.py
views.py
File: mommy_recipes.py
from model_mommy.recipe import Recipe
from family.models import Person
person = Recipe(
Person,
name = 'John Doe',
nickname = 'joe',
age = 18,
birthday = date.today(),
appointment = datetime.now()
)
Note
You don’t have to declare all the fields if you don’t want to. Omitted fields will be generated automatically.
File: test_model.py
# -*- coding:utf-8 -*-
#Core Django imports
from django.test import TestCase
#Third-party app imports
from model_mommy import mommy
from model_mommy.recipe import Recipe, foreign_key
# Relative imports of the 'app-name' package
from .models import Person, Contact
class PersonTestModel(TestCase):
"""
Class to test the model
Person
"""
def setUp(self):
"""
Set up all the tests
"""
self.person_one = mommy.make_recipe(
'family.person'
)
self.person_simpsons = Recipe(
Person,
name='Moe',
)
self.contact = Recipe(
Contact,
person=foreign_key(self.person_simpsons),
tel='3333333eeeeR'
)
def test_kind_contact_create_instance(self):
"""
True if create instance
"""
contact = self.contact.make()
self.assertIsInstance(contact, Contact)
Or if you don’t want a persisted instance:
from model_mommy import mommy
mommy.prepare_recipe('family.person')
Another examples
Note
You can use the _quantity parameter as well if you want to create more than one object from a single recipe.
Note
You can define recipes locally to your module or test case as well. This can be useful for cases where a particular set of values may be unique to a particular test case, but used repeatedly there.
Look:
File: mommy_recipes.py
company_recipe = Recipe(Company, name='WidgetCo'
File: test_model.py
class EmployeeTest(TestCase):
def setUp(self):
self.employee_recipe = Recipe(
Employee,
name=seq('Employee '),
company=company_recipe.make()
)
def test_employee_list(self):
self.employee_recipe.make(_quantity=3)
# test stuff....
def test_employee_tasks(self):
employee1 = self.employee_recipe.make()
task_recipe = Recipe(Task, employee=employee1)
task_recipe.make(status='done')
task_recipe.make(due_date=datetime(2014, 1, 1))
# test stuff....
Recipes with foreign keys¶
You can define foreign_key relations:
from model_mommy.recipe import Recipe, foreign_key
from family.models import Person, Dog
person = Recipe(Person,
name = 'John Doe',
nickname = 'joe',
age = 18,
birthday = date.today(),
appointment = datetime.now()
)
dog = Recipe(Dog,
breed = 'Pug',
owner = foreign_key(person)
)
Notice that person is a recipe.
You may be thinking: “I can put the Person model instance directly in the owner field”. That’s not recommended.
Using the foreign_key is important for 2 reasons:
- Semantics. You’ll know that attribute is a foreign key when you’re reading;
- The associated instance will be created only when you call make_recipe and not during recipe definition;
You can also use related, when you want two or more models to share the same parent:
from model_mommy.recipe import related, Recipe
dog = Recipe(Dog,
breed = 'Pug',
)
other_dog = Recipe(Dog,
breed = 'Boxer',
)
person_with_three_dogs = Recipe(Person,
dog_set = related('dog', 'other_dog')
)
Note this will only work when calling make_recipe because the related manager requires the objects in the related_set to be persisted. That said, calling prepare_recipe the related_set will be empty.
If you want to set m2m relationship you can use related as well:
class Dog(models.Model):
owner = models.ForeignKey('Person')
breed = models.CharField(max_length=50)
created = models.DateTimeField(auto_now_add=True)
friends_with = models.ManyToManyField('Dog')
from model_mommy.recipe import related, Recipe
dog = Recipe(Dog,
breed = 'Pug',
)
dog_with_friends = dog.extend(
friends_with=related(dog, dog),
)
Recipes with callables¶
It’s possible to use callables as recipe’s attribute value.
from datetime import date
from model_mommy.recipe import Recipe
from family.models import Person
person = Recipe(Person,
birthday = date.today,
)
When you call make_recipe, Mommy will set the attribute to the value returned by the callable.
Recipes with iterators¶
You can also use iterators (including generators) to provide multiple values to a recipe.
from itertools import cycle
colors = ['red', 'green', 'blue', 'yellow']
person = Recipe(Person,
favorite_color = cycle(colors)
)
Mommy will use the next value in the iterator every time you create a model from the recipe.
Sequences in recipes¶
Sometimes, you have a field with an unique value and using make can cause random errors. Also, passing an attribute value just to avoid uniqueness validation problems can be tedious. To solve this you can define a sequence with seq
from model_mommy.recipe import Recipe, seq
from family.models import Person
person = Recipe(Person,
name = seq('Joe'),
age = seq(15)
)
p = mommy.make_recipe('myapp.person')
p.name
>>> 'Joe1'
p.age
>>> 16
p = mommy.make_recipe('myapp.person')
p.name
>>> 'Joe2'
p.age
>>> 17
This will append a counter to strings to avoid uniqueness problems and it will sum the counter with numerical values.
You can also provide an optional increment_by argument which will modify incrementing behaviour. This can be an integer, float, Decimal or timedelta.
from datetime import datetime, timedelta
from model_mommy.recipe import Recipe, seq
from family.models import Person
person = Recipe(Person,
age = seq(15, increment_by=3)
height_ft = seq(5.5, increment_by=.25)
# assume today's date is 21/07/2014
appointment = seq(datetime.date(2014, 7, 21), timedelta(days=1))
)
p = mommy.make_recipe('myapp.person')
p.age
>>> 18
p.height_ft
>>> 5.75
p.appointment
>>> datetime.date(2014, 7, 22)
p = mommy.make_recipe('myapp.person')
p.age
>>> 21
p.height_ft
>>> 6.0
p.appointment
>>> datetime.date(2014, 7, 23)
Note
If your Python’s interpreter version is 2.6.x or earlier then increment_by is not available for you. seq will simply ignore this argument.
Overriding recipe definitions¶
Passing values when calling make_recipe or prepare_recipe will override the recipe rule.
from model_mommy import mommy
mommy.make_recipe('model_mommy.person', name='Peter Parker')
This is useful when you have to create multiple objects and you have some unique field, for instance.
Recipe inheritance¶
If you need to reuse and override existent recipe call extend method:
dog = Recipe(Dog,
breed = 'Pug',
owner = foreign_key(person)
)
extended_dog = dog.extend(
breed = 'Super basset',
)
Deprecation Warnings¶
Because of the changes of model_mommy’s API, the following methods are deprecated and will be removed in one of the future releases:
- mommy.make_one -> should use the method mommy.make instead
- mommy.prepare_one -> should use the method mommy.prepare instead
- mommy.make_many -> should use the method mommy.make with the _quantity parameter instead
- mommy.make_many_from_recipe -> should use the method mommy.make_recipe with the _quantity parameter instead
- MOMMY_CUSTOM_FIELDS_GEN -> should use the method mommy.generators.add instead
Known Issues¶
django-taggit¶
Model-mommy identifies django-taggit’s TaggableManager as a normal Django field, which can lead to errors:
TypeError: <class 'taggit.managers.TaggableManager'> is not supported by mommy.
The fix for this is to set blank=True
on your TaggableManager
.
Extensions¶
GeoDjango¶
Works with it? This project has some custom generators for it: https://github.com/sigma-consultoria/mommy_spatial_generators