Merge remote branch 'nvie/dev' into dev

mongoengine/queryset.py

@@ -10,11 +10,18 @@ import copy
 import itertools
 
 __all__ = ['queryset_manager', 'Q', 'InvalidQueryError',
-           'InvalidCollectionError']
+           'InvalidCollectionError', 'DO_NOTHING', 'NULLIFY', 'CASCADE', 'DENY']
+
 
 # The maximum number of items to display in a QuerySet.__repr__
 REPR_OUTPUT_SIZE = 20
 
+# Delete rules
+DO_NOTHING = 0
+NULLIFY = 1
+CASCADE = 2
+DENY = 3
+
 
 class DoesNotExist(Exception):
     pass
@@ -947,6 +954,28 @@ class QuerySet(object):
 
         :param safe: check if the operation succeeded before returning
         """
+        doc = self._document
+
+        # Check for DENY rules before actually deleting/nullifying any other
+        # references
+        for rule_entry in doc._meta['delete_rules']:
+            document_cls, field_name = rule_entry
+            rule = doc._meta['delete_rules'][rule_entry]
+            if rule == DENY and document_cls.objects(**{field_name + '__in': self}).count() > 0:
+                msg = u'Could not delete document (at least %s.%s refers to it)' % \
+                        (document_cls.__name__, field_name)
+                raise OperationError(msg)
+
+        for rule_entry in doc._meta['delete_rules']:
+            document_cls, field_name = rule_entry
+            rule = doc._meta['delete_rules'][rule_entry]
+            if rule == CASCADE:
+                document_cls.objects(**{field_name + '__in': self}).delete(safe=safe)
+            elif rule == NULLIFY:
+                document_cls.objects(**{field_name + '__in': self}).update(
+                        safe_update=safe,
+                        **{'unset__%s' % field_name: 1})
+
         self._collection.remove(self._query, safe=safe)
 
     @classmethod