- The MySQL dialect will now disable :meth:`.ConnectionEvents.handle_error`

events from firing for those statements which it uses internally
to detect if a table exists or not.   This is achieved using an
execution option ``skip_user_error_events`` that disables the handle
error event for the scope of that execution.   In this way, user code
that rewrites exceptions doesn't need to worry about the MySQL
dialect or other dialects that occasionally need to catch
SQLAlchemy specific exceptions.

1 files changed, 28 insertions, 0 deletions

diff --git a/test/engine/test_execute.py b/test/engine/test_execute.py
index 33e116cdf..50cf41311 100644
--- a/test/engine/test_execute.py
+++ b/test/engine/test_execute.py
@@ -1659,6 +1659,34 @@ class HandleErrorTest(fixtures.TestBase):
         is_(ctx.is_disconnect, False)
         is_(ctx.original_exception, nope)
 
+    def test_exception_event_disable_handlers(self):
+        engine = engines.testing_engine()
+
+        class MyException1(Exception):
+            pass
+
+        @event.listens_for(engine, 'handle_error')
+        def err1(context):
+            stmt = context.statement
+
+            if "ERROR_ONE" in str(stmt):
+                raise MyException1("my exception short circuit")
+
+        with engine.connect() as conn:
+            assert_raises(
+                tsa.exc.DBAPIError,
+                conn.execution_options(
+                    skip_user_error_events=True
+                ).execute, "SELECT ERROR_ONE FROM I_DONT_EXIST"
+            )
+
+            assert_raises(
+                MyException1,
+                conn.execution_options(
+                    skip_user_error_events=False
+                ).execute, "SELECT ERROR_ONE FROM I_DONT_EXIST"
+            )
+
     def _test_alter_disconnect(self, orig_error, evt_value):
         engine = engines.testing_engine()