ResultProxy won't autoclose connection until state flag is set

Changed the mechanics of :class:`.ResultProxy` to unconditionally
delay the "autoclose" step until the :class:`.Connection` is done
with the object; in the case where Postgresql ON CONFLICT with
RETURNING returns no rows, autoclose was occurring in this previously
non-existent use case, causing the usual autocommit behavior that
occurs unconditionally upon INSERT/UPDATE/DELETE to fail.

Change-Id: I235a25daf4381b31f523331f810ea04450349722
Fixes: #3955
(cherry picked from commit 8ee363e4917b0dcd64a83b6d26e465c9e61e0ea5)
(cherry picked from commit f52fb5282a046d26b6ee2778e03b995eb117c2ee)

1 files changed, 12 insertions, 4 deletions

diff --git a/lib/sqlalchemy/engine/base.py b/lib/sqlalchemy/engine/base.py
index f680edada..91f4493c2 100644
--- a/lib/sqlalchemy/engine/base.py
+++ b/lib/sqlalchemy/engine/base.py
@@ -1203,14 +1203,22 @@ class Connection(Connectable):
         else:
             result = context.get_result_proxy()
             if result._metadata is None:
-                result._soft_close(_autoclose_connection=False)
+                result._soft_close()
 
         if context.should_autocommit and self._root.__transaction is None:
             self._root._commit_impl(autocommit=True)
 
-        if result._soft_closed and self.should_close_with_result:
-            self.close()
-
+        # for "connectionless" execution, we have to close this
+        # Connection after the statement is complete.
+        if self.should_close_with_result:
+            # ResultProxy already exhausted rows / has no rows.
+            # close us now
+            if result._soft_closed:
+                self.close()
+            else:
+                # ResultProxy will close this Connection when no more
+                # rows to fetch.
+                result._autoclose_connection = True
         return result
 
     def _cursor_execute(self, cursor, statement, parameters, context=None):