- :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, 12 insertions, 5 deletions

diff --git a/lib/sqlalchemy/orm/attributes.py b/lib/sqlalchemy/orm/attributes.py
index da9d62d13..e78973459 100644
--- a/lib/sqlalchemy/orm/attributes.py
+++ b/lib/sqlalchemy/orm/attributes.py
@@ -552,7 +552,6 @@ class AttributeImpl(object):
 
     def get(self, state, dict_, passive=PASSIVE_OFF):
         """Retrieve a value from the given object.
-
         If a callable is assembled on this object's attribute, and
         passive is False, the callable will be executed and the
         resulting value will be set as the new value for this attribute.
@@ -652,8 +651,16 @@ class ScalarAttributeImpl(AttributeImpl):
         del dict_[self.key]
 
     def get_history(self, state, dict_, passive=PASSIVE_OFF):
-        return History.from_scalar_attribute(
-            self, state, dict_.get(self.key, NO_VALUE))
+        if self.key in dict_:
+            return History.from_scalar_attribute(self, state, dict_[self.key])
+        else:
+            if passive & INIT_OK:
+                passive ^= INIT_OK
+            current = self.get(state, dict_, passive=passive)
+            if current is PASSIVE_NO_RESULT:
+                return HISTORY_BLANK
+            else:
+                return History.from_scalar_attribute(self, state, current)
 
     def set(self, state, dict_, value, initiator,
                 passive=PASSIVE_OFF, check_old=None, pop=False):
@@ -1226,7 +1233,7 @@ class History(History):
         original = state.committed_state.get(attribute.key, _NO_HISTORY)
 
         if original is _NO_HISTORY:
-            if current is NO_VALUE:
+            if current is NEVER_SET:
                 return cls((), (), ())
             else:
                 return cls((), [current], ())
@@ -1243,7 +1250,7 @@ class History(History):
                 deleted = ()
             else:
                 deleted = [original]
-            if current is NO_VALUE:
+            if current is NEVER_SET:
                 return cls((), (), deleted)
             else:
                 return cls([current], (), deleted)