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)