1 files changed, 101 insertions, 0 deletions
diff --git a/django/db/models/manager.py b/django/db/models/manager.py
new file mode 100644
index 0000000000..d847631c82
--- /dev/null
+++ b/django/db/models/manager.py
@@ -0,0 +1,101 @@
+from django.utils.functional import curry
+from django.db import backend, connection
+from django.db.models.query import QuerySet
+from django.dispatch import dispatcher
+from django.db.models import signals
+from django.utils.datastructures import SortedDict
+
+# Size of each "chunk" for get_iterator calls.
+# Larger values are slightly faster at the expense of more storage space.
+GET_ITERATOR_CHUNK_SIZE = 100
+
+def ensure_default_manager(sender):
+    cls = sender
+    if not hasattr(cls, '_default_manager'):
+        # Create the default manager, if needed.
+        if hasattr(cls, 'objects'):
+            raise ValueError, "Model %s must specify a custom Manager, because it has a field named 'objects'" % name
+        cls.add_to_class('objects', Manager())
+
+dispatcher.connect(ensure_default_manager, signal=signals.class_prepared)
+
+class Manager(object):
+    # Tracks each time a Manager instance is created. Used to retain order.
+    creation_counter = 0
+
+    def __init__(self):
+        super(Manager, self).__init__()
+        # Increase the creation counter, and save our local copy.
+        self.creation_counter = Manager.creation_counter
+        Manager.creation_counter += 1
+        self.model = None
+
+    def contribute_to_class(self, model, name):
+        # TODO: Use weakref because of possible memory leak / circular reference.
+        self.model = model
+        setattr(model, name, ManagerDescriptor(self))
+        if not hasattr(model, '_default_manager') or self.creation_counter < model._default_manager.creation_counter:
+            model._default_manager = self
+
+    #######################
+    # PROXIES TO QUERYSET #
+    #######################
+
+    def get_query_set(self):
+        """Returns a new QuerySet object.  Subclasses can override this method
+        to easily customise the behaviour of the Manager.
+        """
+        return QuerySet(self.model)
+
+    def all(self):
+        return self.get_query_set()
+
+    def count(self):
+        return self.get_query_set().count()
+
+    def dates(self, *args, **kwargs):
+        return self.get_query_set().dates(*args, **kwargs)
+
+    def distinct(self, *args, **kwargs):
+        return self.get_query_set().distinct(*args, **kwargs)
+
+    def extra(self, *args, **kwargs):
+        return self.get_query_set().extra(*args, **kwargs)
+
+    def get(self, *args, **kwargs):
+        return self.get_query_set().get(*args, **kwargs)
+
+    def filter(self, *args, **kwargs):
+        return self.get_query_set().filter(*args, **kwargs)
+
+    def exclude(self, *args, **kwargs):
+        return self.get_query_set().exclude(*args, **kwargs)
+
+    def in_bulk(self, *args, **kwargs):
+        return self.get_query_set().in_bulk(*args, **kwargs)
+
+    def iterator(self, *args, **kwargs):
+        return self.get_query_set().iterator(*args, **kwargs)
+
+    def latest(self, *args, **kwargs):
+        return self.get_query_set().latest(*args, **kwargs)
+
+    def order_by(self, *args, **kwargs):
+        return self.get_query_set().order_by(*args, **kwargs)
+
+    def select_related(self, *args, **kwargs):
+        return self.get_query_set().select_related(*args, **kwargs)
+
+    def values(self, *args, **kwargs):
+        return self.get_query_set().values(*args, **kwargs)
+
+class ManagerDescriptor(object):
+    # This class ensures managers aren't accessible via model instances.
+    # For example, Poll.objects works, but poll_obj.objects raises AttributeError.
+    def __init__(self, manager):
+        self.manager = manager
+
+    def __get__(self, instance, type=None):
+        if instance != None:
+            raise AttributeError, "Manager isn't accessible via %s instances" % type.__name__
+        return self.manager