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from functools import partial
from mongoengine.queryset.queryset import QuerySet
__all__ = ("queryset_manager", "QuerySetManager")
class QuerySetManager:
"""
The default QuerySet Manager.
Custom QuerySet Manager functions can extend this class and users can
add extra queryset functionality. Any custom manager methods must accept a
:class:`~mongoengine.Document` class as its first argument, and a
:class:`~mongoengine.queryset.QuerySet` as its second argument.
The method function should return a :class:`~mongoengine.queryset.QuerySet`
, probably the same one that was passed in, but modified in some way.
"""
get_queryset = None
default = QuerySet
def __init__(self, queryset_func=None):
if queryset_func:
self.get_queryset = queryset_func
def __get__(self, instance, owner):
"""Descriptor for instantiating a new QuerySet object when
Document.objects is accessed.
"""
if instance is not None:
# Document object being used rather than a document class
return self
# owner is the document that contains the QuerySetManager
queryset_class = owner._meta.get("queryset_class", self.default)
queryset = queryset_class(owner, owner._get_collection())
if self.get_queryset:
arg_count = self.get_queryset.__code__.co_argcount
if arg_count == 1:
queryset = self.get_queryset(queryset)
elif arg_count == 2:
queryset = self.get_queryset(owner, queryset)
else:
queryset = partial(self.get_queryset, owner, queryset)
return queryset
def queryset_manager(func):
"""Decorator that allows you to define custom QuerySet managers on
:class:`~mongoengine.Document` classes. The manager must be a function that
accepts a :class:`~mongoengine.Document` class as its first argument, and a
:class:`~mongoengine.queryset.QuerySet` as its second argument. The method
function should return a :class:`~mongoengine.queryset.QuerySet`, probably
the same one that was passed in, but modified in some way.
"""
return QuerySetManager(func)
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