diff options
Diffstat (limited to 'lib/sqlalchemy')
| -rw-r--r-- | lib/sqlalchemy/orm/attributes.py | 20 | ||||
| -rw-r--r-- | lib/sqlalchemy/util/__init__.py | 3 | ||||
| -rw-r--r-- | lib/sqlalchemy/util/_collections.py | 30 |
3 files changed, 46 insertions, 7 deletions
diff --git a/lib/sqlalchemy/orm/attributes.py b/lib/sqlalchemy/orm/attributes.py index 5ba8be439..b08c46741 100644 --- a/lib/sqlalchemy/orm/attributes.py +++ b/lib/sqlalchemy/orm/attributes.py @@ -1273,19 +1273,27 @@ def backref_listeners(attribute, key, uselist): if not child_impl.collection and not child_impl.dynamic: check_remove_token = child_impl._remove_token check_replace_token = child_impl._replace_token + check_for_dupes_on_remove = uselist and not parent_impl.dynamic else: check_remove_token = child_impl._remove_token check_replace_token = child_impl._bulk_replace_token \ if child_impl.collection else None + check_for_dupes_on_remove = False if initiator is not check_remove_token and \ initiator is not check_replace_token: - child_impl.pop( - child_state, - child_dict, - state.obj(), - initiator, - passive=PASSIVE_NO_FETCH) + + if not check_for_dupes_on_remove or \ + not util.has_dupes( + # when this event is called, the item is usually + # present in the list, except for a pop() operation. + state.dict[parent_impl.key], child): + child_impl.pop( + child_state, + child_dict, + state.obj(), + initiator, + passive=PASSIVE_NO_FETCH) if uselist: event.listen(attribute, "append", diff --git a/lib/sqlalchemy/util/__init__.py b/lib/sqlalchemy/util/__init__.py index 9229d0797..d8c28d6af 100644 --- a/lib/sqlalchemy/util/__init__.py +++ b/lib/sqlalchemy/util/__init__.py @@ -21,7 +21,8 @@ from ._collections import KeyedTuple, ImmutableContainer, immutabledict, \ UniqueAppender, PopulateDict, EMPTY_SET, to_list, to_set, \ to_column_set, update_copy, flatten_iterator, has_intersection, \ LRUCache, ScopedRegistry, ThreadLocalRegistry, WeakSequence, \ - coerce_generator_arg, lightweight_named_tuple, collections_abc + coerce_generator_arg, lightweight_named_tuple, collections_abc, \ + has_dupes from .langhelpers import iterate_attributes, class_hierarchy, \ portable_instancemethod, unbound_method_to_callable, \ diff --git a/lib/sqlalchemy/util/_collections.py b/lib/sqlalchemy/util/_collections.py index 3152458bf..43440134a 100644 --- a/lib/sqlalchemy/util/_collections.py +++ b/lib/sqlalchemy/util/_collections.py @@ -1057,3 +1057,33 @@ def _iter_id(iterable): for item in iterable: yield id(item), item + + +def has_dupes(sequence, target): + """Given a sequence and search object, return True if there's more + than one, False if zero or one of them. + + + """ + # compare to .index version below, this version introduces less function + # overhead and is usually the same speed. At 15000 items (way bigger than + # a relationship-bound collection in memory usually is) it begins to + # fall behind the other version only by microseconds. + c = 0 + for item in sequence: + if item is target: + c += 1 + if c > 1: + return True + return False + +# .index version. the two __contains__ calls as well +# as .index() and isinstance() slow this down. +# def has_dupes(sequence, target): +# if target not in sequence: +# return False +# elif not isinstance(sequence, collections_abc.Sequence): +# return False +# +# idx = sequence.index(target) +# return target in sequence[idx + 1:] |