From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Fri, 22 Nov 2019 15:27:02 +0000 (-0500)
Subject: Don't raise w/ raiseload strategy for many-to-one history in flush
X-Git-Tag: rel_1_3_12~12
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2e6754ac0da5c1985485c8c075c6585bc6d1f00e;p=thirdparty%2Fsqlalchemy%2Fsqlalchemy.git

Don't raise w/ raiseload strategy for many-to-one history in flush

Fixed issue involving ``lazy="raise"`` strategy where an ORM delete of an
object would raise for a simple "use-get" style many-to-one relationship
that had lazy="raise" configured.  This is inconsistent vs. the change
introduced in 1.3 as part of :ticket:`4353`, where it was established that
a history operation that does not expect emit SQL should bypass the
``lazy="raise"`` check, and instead effectively treat it as
``lazy="raise_on_sql"`` for this case.  The fix adjusts the lazy loader
strategy to not raise for the case where the lazy load was instructed that
it should not emit SQL if the object were not present.

Fixes: #4997
Change-Id: I4deb8c129900f28321c4a5c48301db5fe2aedf78
(cherry picked from commit ff4b63c2bc5f118d5ec1aacff06708dbc08a37a7)
---

diff --git a/doc/build/changelog/unreleased_13/4997.rst b/doc/build/changelog/unreleased_13/4997.rst
new file mode 100644
index 0000000000..f58caf0436
--- /dev/null
+++ b/doc/build/changelog/unreleased_13/4997.rst
@@ -0,0 +1,13 @@
+.. change::
+    :tags: bug, orm
+    :tickets: 4997
+
+    Fixed issue involving ``lazy="raise"`` strategy where an ORM delete of an
+    object would raise for a simple "use-get" style many-to-one relationship
+    that had lazy="raise" configured.  This is inconsistent vs. the change
+    introduced in 1.3 as part of :ticket:`4353`, where it was established that
+    a history operation that does not expect emit SQL should bypass the
+    ``lazy="raise"`` check, and instead effectively treat it as
+    ``lazy="raise_on_sql"`` for this case.  The fix adjusts the lazy loader
+    strategy to not raise for the case where the lazy load was instructed that
+    it should not emit SQL if the object were not present.
diff --git a/lib/sqlalchemy/orm/strategies.py b/lib/sqlalchemy/orm/strategies.py
index caf708950c..576e148cbb 100644
--- a/lib/sqlalchemy/orm/strategies.py
+++ b/lib/sqlalchemy/orm/strategies.py
@@ -532,9 +532,11 @@ class LazyLoader(AbstractRelationshipLoader, util.MemoizedSlots):
         self.is_aliased_class = inspect(self.entity).is_aliased_class
 
         join_condition = self.parent_property._join_condition
-        self._lazywhere, self._bind_to_col, self._equated_columns = (
-            join_condition.create_lazy_clause()
-        )
+        (
+            self._lazywhere,
+            self._bind_to_col,
+            self._equated_columns,
+        ) = join_condition.create_lazy_clause()
 
         (
             self._rev_lazywhere,
@@ -679,7 +681,22 @@ class LazyLoader(AbstractRelationshipLoader, util.MemoizedSlots):
         ):
             return attributes.PASSIVE_NO_RESULT
 
-        if self._raise_always and not passive & attributes.NO_RAISE:
+        if (
+            # we were given lazy="raise"
+            self._raise_always
+            # the no_raise history-related flag was not passed
+            and not passive & attributes.NO_RAISE
+            and (
+                # if we are use_get and related_object_ok is disabled,
+                # which means we are at most looking in the identity map
+                # for history purposes or otherwise returning
+                # PASSIVE_NO_RESULT, don't raise.  This is also a
+                # history-related flag
+                not self.use_get
+                or passive & attributes.RELATED_OBJECT_OK
+            )
+        ):
+
             self._invoke_raise_load(state, passive, "raise")
 
         session = _state_session(state)
diff --git a/test/orm/test_relationships.py b/test/orm/test_relationships.py
index 60cfde3c3d..fdacdc80c0 100644
--- a/test/orm/test_relationships.py
+++ b/test/orm/test_relationships.py
@@ -5356,6 +5356,17 @@ class InactiveHistoryNoRaiseTest(_fixtures.FixtureTest):
 
         s.commit()
 
+        eq_(s.query(Address).count(), 1)
+        eq_(s.query(User).count(), 1)
+
+        # test for issue #4997
+        # delete of Address should proceed, as User object does not
+        # need to be loaded
+        s.delete(a1)
+        s.commit()
+        eq_(s.query(Address).count(), 0)
+        eq_(s.query(User).count(), 1)
+
 
 class RelationDeprecationTest(fixtures.MappedTest):