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-rw-r--r--lib/sqlalchemy/orm/attributes.py18
1 files changed, 18 insertions, 0 deletions
diff --git a/lib/sqlalchemy/orm/attributes.py b/lib/sqlalchemy/orm/attributes.py
index 879b88a92..1b8c8c7f3 100644
--- a/lib/sqlalchemy/orm/attributes.py
+++ b/lib/sqlalchemy/orm/attributes.py
@@ -1724,6 +1724,17 @@ def get_history(obj, key, passive=PASSIVE_OFF):
"""Return a :class:`.History` record for the given object
and attribute key.
+ This is the **pre-flush** history for a given attribute, which is
+ reset each time the :class:`.Session` flushes changes to the
+ current database transaction.
+
+ .. note::
+
+ Prefer to use the :attr:`.AttributeState.history` and
+ :meth:`.AttributeState.load_history` accessors to retrieve the
+ :class:`.History` for instance attributes.
+
+
:param obj: an object whose class is instrumented by the
attributes package.
@@ -1735,6 +1746,13 @@ def get_history(obj, key, passive=PASSIVE_OFF):
:attr:`.PASSIVE_OFF` indicating all necessary SQL
should be emitted.
+ .. seealso::
+
+ :attr:`.AttributeState.history`
+
+ :meth:`.AttributeState.load_history` - retrieve history
+ using loader callables if the value is not locally present.
+
"""
if passive is True:
util.warn_deprecated(