f4132140f5
The regression was caused by using .none() when querying for related models, and the origin field's value was None. This resulted in missing custom related manager subclass as .none() returns plain QuerySet. This isn't backport from master, in master .none() correctly preserves the queryset's class. Patch provided by Simon Charette, with some minor polish by committer.
87 lines
2.4 KiB
Python
87 lines
2.4 KiB
Python
"""
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23. Giving models a custom manager
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You can use a custom ``Manager`` in a particular model by extending the base
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``Manager`` class and instantiating your custom ``Manager`` in your model.
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There are two reasons you might want to customize a ``Manager``: to add extra
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``Manager`` methods, and/or to modify the initial ``QuerySet`` the ``Manager``
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returns.
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"""
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from __future__ import unicode_literals
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from django.db import models
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from django.utils.encoding import python_2_unicode_compatible
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# An example of a custom manager called "objects".
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class PersonManager(models.Manager):
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def get_fun_people(self):
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return self.filter(fun=True)
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@python_2_unicode_compatible
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class Person(models.Model):
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first_name = models.CharField(max_length=30)
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last_name = models.CharField(max_length=30)
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fun = models.BooleanField()
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objects = PersonManager()
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def __str__(self):
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return "%s %s" % (self.first_name, self.last_name)
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# An example of a custom manager that sets get_query_set().
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class PublishedBookManager(models.Manager):
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def get_query_set(self):
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return super(PublishedBookManager, self).get_query_set().filter(is_published=True)
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@python_2_unicode_compatible
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class Book(models.Model):
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title = models.CharField(max_length=50)
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author = models.CharField(max_length=30)
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is_published = models.BooleanField()
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published_objects = PublishedBookManager()
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authors = models.ManyToManyField(Person, related_name='books')
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def __str__(self):
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return self.title
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# An example of providing multiple custom managers.
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class FastCarManager(models.Manager):
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def get_query_set(self):
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return super(FastCarManager, self).get_query_set().filter(top_speed__gt=150)
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@python_2_unicode_compatible
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class Car(models.Model):
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name = models.CharField(max_length=10)
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mileage = models.IntegerField()
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top_speed = models.IntegerField(help_text="In miles per hour.")
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cars = models.Manager()
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fast_cars = FastCarManager()
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def __str__(self):
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return self.name
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# Bug #19652
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class ObjectQuerySet(models.query.QuerySet):
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pass
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class ObjectManager(models.Manager):
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use_for_related_fields = True
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def get_query_set(self):
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return ObjectQuerySet(self.model, using=self._db)
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class RelatedObject(models.Model):
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pass
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class Object(models.Model):
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related = models.ForeignKey(RelatedObject, related_name='objs')
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objects = ObjectManager()
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