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.
It’s also possible to store the Recipes in a module called mommy_recipes.py at your app’s root directory. This recipes can later be used with the make_recipe function:
fixtures/ migrations/ templates/ tests/ __init__.py admin.py managers.py models.py mommy_recipes.py urls.py views.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() )
You don’t have to declare all the fields if you don’t want to. Omitted fields will be generated automatically.
from django.test import TestCase 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): # Load the recipe 'person' from 'family/mommy_recipes.py' 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')
You can use the _quantity parameter as well if you want to create more than one object from a single recipe.
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.
company_recipe = Recipe(Company, name='WidgetCo')
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 date, 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(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)
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.
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', )