Ticket #17270: manager.5.py

File manager.5.py, 2.3 KB (added by Wojciech Banaś <fizista@…>, 13 years ago)

Another solution, tested, working, downwards compatible, decorator

Line 
1from types import MethodType
2from django.db import models
3from django.db.models.query import QuerySet
4from django.db.models.query import EmptyQuerySet
5
6class ManagerQuerySetDecorator(models.Manager):
7 """
8 Extends the operation methods of the manager on subqueries QuerySet objects.
9
10 How to use:
11
12 class ManagerQuerySet(models.query.QuerySet):
13 def get_fun_people(self):
14 return self.filter(fun=True)
15
16 def get_not_fun_people(self):
17 return self.filter(fun=False)
18
19 class PersonManager(models.Manager):
20 def __init__(self):
21 super(PersonManager, self).__init__()
22 self.implement_queryset_cls(ManagerQuerySet)
23 self.implement_queryset_methods('get_fun_people', 'get_not_fun_people')
24
25 class Person(models.Model):
26 first_name = models.CharField(max_length=30)
27 last_name = models.CharField(max_length=30)
28 fun = models.BooleanField()
29 objects = PersonManager()
30 objects_second = PersonManagerSecond(ManagerQuerySet, ['get_fun_people', 'get_not_fun_people'])
31
32 def __unicode__(self):
33 return u"%s %s" % (self.first_name, self.last_name)
34
35 # This works without a decorator
36 Person.objects.get_fun_people().filter(firstname='John')
37
38 # The decorator also provides such a possibility, which does not work currently in django.
39 Person.objects.filter(firstname='John').get_fun_people()
40 """
41 def __init__(self, queryset_cls=None, queryset_method_names=[]):
42 super(ManagerQuerySetDecorator, self).__init__()
43 self._queryset_cls = queryset_cls or QuerySet
44 self.implement_queryset_methods(*queryset_method_names)
45
46 def implement_queryset_cls(self, cls):
47 self._queryset_cls = cls
48
49 def implement_queryset_methods(self, *method_names):
50 for method_name in method_names:
51 self.implement_queryset_method(method_name)
52
53 def implement_queryset_method(self, name):
54 def queryset_method_deco(*args, **kwarg):
55 return getattr(self.get_query_set(), name)(*args, **kwarg)
56 setattr(self, name, queryset_method_deco)
57
58 def get_empty_query_set(self):
59 return self._queryset_cls(self.model, using=self._db).none()
60
61 def get_query_set(self):
62 return self._queryset_cls(self.model, using=self._db)
63
64
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