- :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.

2 files changed, 72 insertions, 5 deletions

diff --git a/test/orm/test_attributes.py b/test/orm/test_attributes.py
index de44e4be3..c282bc44c 100644
--- a/test/orm/test_attributes.py
+++ b/test/orm/test_attributes.py
@@ -1339,7 +1339,7 @@ class PendingBackrefTest(fixtures.ORMTest):
             ]
         )
 
-    def test_lazy_history(self):
+    def test_lazy_history_collection(self):
         Post, Blog, lazy_posts = self._fixture()
 
         p1, p2, p3 = Post("post 1"), Post("post 2"), Post("post 3")
@@ -1511,6 +1511,12 @@ class HistoryTest(fixtures.TestBase):
         return Foo, Bar
 
     def _someattr_history(self, f, **kw):
+        passive = kw.pop('passive', None)
+        if passive is True:
+            kw['passive'] = attributes.PASSIVE_NO_INITIALIZE
+        elif passive is False:
+            kw['passive'] = attributes.PASSIVE_OFF
+
         return attributes.get_state_history(
                     attributes.instance_state(f),
                     'someattr', **kw)
@@ -1685,19 +1691,19 @@ class HistoryTest(fixtures.TestBase):
         Foo = self._fixture(uselist=True, useobject=True,
                                 active_history=True)
         f = Foo()
-        eq_(self._someattr_history(f, passive=True), ((), (), ()))
+        eq_(self._someattr_history(f, passive=True), (None, None, None))
 
     def test_scalar_obj_never_set(self):
         Foo = self._fixture(uselist=False, useobject=True,
                                 active_history=True)
         f = Foo()
-        eq_(self._someattr_history(f, passive=True), ((), (), ()))
+        eq_(self._someattr_history(f, passive=True), (None, None, None))
 
     def test_scalar_never_set(self):
         Foo = self._fixture(uselist=False, useobject=False,
                                 active_history=True)
         f = Foo()
-        eq_(self._someattr_history(f, passive=True), ((), (), ()))
+        eq_(self._someattr_history(f, passive=True), (None, None, None))
 
     def test_scalar_active_set(self):
         Foo = self._fixture(uselist=False, useobject=False,
@@ -1793,6 +1799,24 @@ class HistoryTest(fixtures.TestBase):
         eq_(self._someattr_history(f), (['two'], (), ()))
 
 
+    def test_scalar_passive_flag(self):
+        Foo = self._fixture(uselist=False, useobject=False,
+                                active_history=True)
+        f = Foo()
+        f.someattr = 'one'
+        eq_(self._someattr_history(f), (['one'], (), ()))
+
+        self._commit_someattr(f)
+
+        state = attributes.instance_state(f)
+        state._expire_attribute_pre_commit(state.dict, 'someattr')
+
+        def scalar_loader(state, toload):
+            state.dict['someattr'] = 'one'
+        state.manager.deferred_scalar_loader = scalar_loader
+
+        eq_(self._someattr_history(f), ((), ['one'], ()))
+
 
     def test_scalar_inplace_mutation_set(self):
         Foo = self._fixture(uselist=False, useobject=False,
@@ -1848,6 +1872,7 @@ class HistoryTest(fixtures.TestBase):
         f.someattr = ['a']
         eq_(self._someattr_history(f), ([['a']], (), ()))
 
+
     def test_use_object_init(self):
         Foo, Bar = self._two_obj_fixture(uselist=False)
         f = Foo()
diff --git a/test/orm/test_inspect.py b/test/orm/test_inspect.py
index 61c1fd93e..ed8ab32e9 100644
--- a/test/orm/test_inspect.py
+++ b/test/orm/test_inspect.py
@@ -365,7 +365,7 @@ class TestORMInspection(_fixtures.FixtureTest):
             []
         )
 
-    def test_instance_state_attr_hist(self):
+    def test_instance_state_collection_attr_hist(self):
         User = self.classes.User
         u1 = User(name='ed')
         insp = inspect(u1)
@@ -379,6 +379,48 @@ class TestORMInspection(_fixtures.FixtureTest):
             hist.unchanged, []
         )
 
+    def test_instance_state_scalar_attr_hist(self):
+        User = self.classes.User
+        u1 = User(name='ed')
+        sess = Session()
+        sess.add(u1)
+        sess.commit()
+        assert 'name' not in u1.__dict__
+        insp = inspect(u1)
+        hist = insp.attrs.name.history
+        eq_(
+            hist.unchanged, None
+        )
+        assert 'name' not in u1.__dict__
+
+    def test_instance_state_collection_attr_load_hist(self):
+        User = self.classes.User
+        u1 = User(name='ed')
+        insp = inspect(u1)
+        hist = insp.attrs.addresses.load_history()
+        eq_(
+            hist.unchanged, ()
+        )
+        u1.addresses
+        hist = insp.attrs.addresses.load_history()
+        eq_(
+            hist.unchanged, []
+        )
+
+    def test_instance_state_scalar_attr_hist_load(self):
+        User = self.classes.User
+        u1 = User(name='ed')
+        sess = Session()
+        sess.add(u1)
+        sess.commit()
+        assert 'name' not in u1.__dict__
+        insp = inspect(u1)
+        hist = insp.attrs.name.load_history()
+        eq_(
+            hist.unchanged, ['ed']
+        )
+        assert 'name' in u1.__dict__
+
     def test_instance_state_ident_transient(self):
         User = self.classes.User
         u1 = User(name='ed')