diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/ref/models/instances.txt | 19 | ||||
| -rw-r--r-- | docs/releases/1.7.txt | 8 |
2 files changed, 27 insertions, 0 deletions
diff --git a/docs/ref/models/instances.txt b/docs/ref/models/instances.txt index 6295eb0407..da657a9a01 100644 --- a/docs/ref/models/instances.txt +++ b/docs/ref/models/instances.txt @@ -521,6 +521,25 @@ For example:: In previous versions only instances of the exact same class and same primary key value were considered equal. +``__hash__`` +------------ + +.. method:: Model.__hash__() + +The ``__hash__`` method is based on the instance's primary key value. It +is effectively hash(obj.pk). If the instance doesn't have a primary key +value then a ``TypeError`` will be raised (otherwise the ``__hash__`` +method would return different values before and after the instance is +saved, but changing the ``__hash__`` value of an instance `is forbidden +in Python`_). + +.. versionchanged:: 1.7 + + In previous versions instance's without primary key value were + hashable. + +.. _is forbidden in Python: http://docs.python.org/reference/datamodel.html#object.__hash__ + ``get_absolute_url`` -------------------- diff --git a/docs/releases/1.7.txt b/docs/releases/1.7.txt index 774d9d3161..6480a2505f 100644 --- a/docs/releases/1.7.txt +++ b/docs/releases/1.7.txt @@ -199,6 +199,14 @@ Miscellaneous equal when primary keys match. Previously only instances of exact same class were considered equal on primary key match. +* The :meth:`django.db.models.Model.__eq__` method has changed such that + two ``Model`` instances without primary key values won't be considered + equal (unless they are the same instance). + +* The :meth:`django.db.models.Model.__hash__` will now raise ``TypeError`` + when called on an instance without a primary key value. This is done to + avoid mutable ``__hash__`` values in containers. + Features deprecated in 1.7 ========================== |