mirror of
https://github.com/django/django.git
synced 2024-12-27 19:46:22 +00:00
7d03ca9e86
git-svn-id: http://code.djangoproject.com/svn/django/trunk@9898 bcc190cf-cafb-0310-a4f2-bffc1f526a37
84 lines
3.3 KiB
Python
84 lines
3.3 KiB
Python
"""
|
|
Tests for F() query expression syntax.
|
|
"""
|
|
|
|
from django.db import models
|
|
|
|
class Employee(models.Model):
|
|
firstname = models.CharField(max_length=50)
|
|
lastname = models.CharField(max_length=50)
|
|
|
|
def __unicode__(self):
|
|
return u'%s %s' % (self.firstname, self.lastname)
|
|
|
|
class Company(models.Model):
|
|
name = models.CharField(max_length=100)
|
|
num_employees = models.PositiveIntegerField()
|
|
num_chairs = models.PositiveIntegerField()
|
|
ceo = models.ForeignKey(
|
|
Employee,
|
|
related_name='company_ceo_set')
|
|
point_of_contact = models.ForeignKey(
|
|
Employee,
|
|
related_name='company_point_of_contact_set',
|
|
null=True)
|
|
|
|
def __unicode__(self):
|
|
return self.name
|
|
|
|
|
|
__test__ = {'API_TESTS': """
|
|
>>> from django.db.models import F
|
|
|
|
>>> Company(name='Example Inc.', num_employees=2300, num_chairs=5,
|
|
... ceo=Employee.objects.create(firstname='Joe', lastname='Smith')).save()
|
|
>>> Company(name='Foobar Ltd.', num_employees=3, num_chairs=3,
|
|
... ceo=Employee.objects.create(firstname='Frank', lastname='Meyer')).save()
|
|
>>> Company(name='Test GmbH', num_employees=32, num_chairs=1,
|
|
... ceo=Employee.objects.create(firstname='Max', lastname='Mustermann')).save()
|
|
|
|
>>> company_query = Company.objects.values('name','num_employees','num_chairs').order_by('name','num_employees','num_chairs')
|
|
|
|
# We can filter for companies where the number of employees is greater than the
|
|
# number of chairs.
|
|
>>> company_query.filter(num_employees__gt=F('num_chairs'))
|
|
[{'num_chairs': 5, 'name': u'Example Inc.', 'num_employees': 2300}, {'num_chairs': 1, 'name': u'Test GmbH', 'num_employees': 32}]
|
|
|
|
# We can set one field to have the value of another field
|
|
# Make sure we have enough chairs
|
|
>>> _ = company_query.update(num_chairs=F('num_employees'))
|
|
>>> company_query
|
|
[{'num_chairs': 2300, 'name': u'Example Inc.', 'num_employees': 2300}, {'num_chairs': 3, 'name': u'Foobar Ltd.', 'num_employees': 3}, {'num_chairs': 32, 'name': u'Test GmbH', 'num_employees': 32}]
|
|
|
|
# We can perform arithmetic operations in expressions
|
|
# Make sure we have 2 spare chairs
|
|
>>> _ =company_query.update(num_chairs=F('num_employees')+2)
|
|
>>> company_query
|
|
[{'num_chairs': 2302, 'name': u'Example Inc.', 'num_employees': 2300}, {'num_chairs': 5, 'name': u'Foobar Ltd.', 'num_employees': 3}, {'num_chairs': 34, 'name': u'Test GmbH', 'num_employees': 32}]
|
|
|
|
# The relation of a foreign key can become copied over to an other foreign key.
|
|
>>> Company.objects.update(point_of_contact=F('ceo'))
|
|
3
|
|
|
|
>>> [c.point_of_contact for c in Company.objects.all()]
|
|
[<Employee: Joe Smith>, <Employee: Frank Meyer>, <Employee: Max Mustermann>]
|
|
|
|
>>> c = Company.objects.all()[0]
|
|
>>> c.point_of_contact = Employee.objects.create(firstname="Guido", lastname="van Rossum")
|
|
>>> c.save()
|
|
|
|
# F Expressions can also span joins
|
|
>>> Company.objects.filter(ceo__firstname=F('point_of_contact__firstname')).distinct()
|
|
[<Company: Foobar Ltd.>, <Company: Test GmbH>]
|
|
|
|
>>> _ = Company.objects.exclude(ceo__firstname=F('point_of_contact__firstname')).update(name='foo')
|
|
>>> Company.objects.exclude(ceo__firstname=F('point_of_contact__firstname')).get().name
|
|
u'foo'
|
|
|
|
>>> _ = Company.objects.exclude(ceo__firstname=F('point_of_contact__firstname')).update(name=F('point_of_contact__lastname'))
|
|
Traceback (most recent call last):
|
|
...
|
|
FieldError: Joined field references are not permitted in this query
|
|
|
|
"""}
|