With django-delegate, you get AUTOMATICALLY CHAINABLE MANAGER/QUERYSET DELEGATE METHODS.
Normally, by defining manager methods, Django lets you do this:
>>> SomeModel.objects.custom_query()... but it WON'T let you do this:
>>> SomeModel.objects.custom_query().another_custom_query()... unless you duplicate your methods and define a redundant queryset subclass... UNTIL NOW.
With DelegateManager and @delegate, you can write maintainable custom-query logic with free chaining. instead of defining manager methods, you define queryset methods, decorate those you'd like to delegate, and a two-line DelegateManager subclass specifying the queryset. ET VIOLA. Like so:
from delegate import DelegateManager, delegate
class CustomQuerySet(models.query.QuerySet):
@delegate
def qs_method(self, some_value):
return self.filter(some_param__icontains=some_value)
def dont_delegate_me(self):
return self.filter(some_other_param="something else")
class CustomManager(DelegateManager):
__queryset__ = CustomQuerySet
class SomeModel(models.Model):
objects = CustomManager()
# this will work:
SomeModel.objects.qs_method('yo dogg')
# this will also work:
SomeModel.objects.qs_method('yo dogg').qs_method('i heard you like queryset method delegation')To delegate all of the methods in a QuerySet automatically, you can create a subclass of DelegateQuerySet. These two QuerySet subclasses work identically:
from delegate import DelegateQuerySet, delegate
class ManualDelegator(models.query.QuerySet):
@delegate
def qs_method(self):
# ...
class AutomaticDelegator(DelegateQuerySet):
def qs_method(self):
# ...You can also apply the @delegate decorator directly to a class -- this permits you to delegate all the methods in a class without disrupting its inheritance chain. This example works identically to the previous two:
from delegate import delegate
@delegate
class CustomQuerySet(models.query.QuerySet):
def qs_method(self, some_value):
return self.filter(some_param__icontains=some_value)