- :func:`.attributes.get_history()` when used with a scalar column-mapped

attribute will now honor the "passive" flag
passed to it; as this defaults to ``PASSIVE_OFF``, the function will
by default query the database if the value is not present.
This is a behavioral change vs. 0.8.  [ticket:2787]
- Added new method :meth:`.AttributeState.load_history`, works like
:attr:`.AttributeState.history` but also fires loader callables.

1 files changed, 31 insertions, 1 deletions

diff --git a/lib/sqlalchemy/orm/state.py b/lib/sqlalchemy/orm/state.py
index 8d73c9426..957e29700 100644
--- a/lib/sqlalchemy/orm/state.py
+++ b/lib/sqlalchemy/orm/state.py
@@ -16,7 +16,7 @@ from .. import util
 from . import exc as orm_exc, interfaces
 from .path_registry import PathRegistry
 from .base import PASSIVE_NO_RESULT, SQL_OK, NEVER_SET, ATTR_WAS_SET, \
-        NO_VALUE, PASSIVE_NO_INITIALIZE
+        NO_VALUE, PASSIVE_NO_INITIALIZE, INIT_OK, PASSIVE_OFF
 from . import base
 
 class InstanceState(interfaces._InspectionAttr):
@@ -555,10 +555,40 @@ class AttributeState(object):
         """Return the current pre-flush change history for
         this attribute, via the :class:`.History` interface.
 
+        This method will **not** emit loader callables if the value of the
+        attribute is unloaded.
+
+        .. seealso::
+
+            :meth:`.AttributeState.load_history` - retrieve history
+            using loader callables if the value is not locally present.
+
+            :func:`.attributes.get_history` - underlying function
+
         """
         return self.state.get_history(self.key,
                     PASSIVE_NO_INITIALIZE)
 
+    def load_history(self):
+        """Return the current pre-flush change history for
+        this attribute, via the :class:`.History` interface.
+
+        This method **will** emit loader callables if the value of the
+        attribute is unloaded.
+
+        .. seealso::
+
+            :attr:`.AttributeState.history`
+
+            :func:`.attributes.get_history` - underlying function
+
+        .. versionadded:: 0.9.0
+
+        """
+        return self.state.get_history(self.key,
+                    PASSIVE_OFF ^ INIT_OK)
+
+
 
 class PendingCollection(object):
     """A writable placeholder for an unloaded collection.