DbAPiHook: Don't log a warning message if placeholder is None and make sure warning message is formatted correctly

airflow/providers/common/sql/hooks/sql.py

@@ -185,14 +185,15 @@ def __init__(self, *args, schema: str | None = None, log_sql: bool = True, **kwa
     def placeholder(self):
         conn = self.get_connection(getattr(self, self.conn_name_attr))
         placeholder = conn.extra_dejson.get("placeholder")
-        if placeholder in SQL_PLACEHOLDERS:
-            return placeholder
-        self.log.warning(
-            "Placeholder defined in Connection '%s' is not listed in 'DEFAULT_SQL_PLACEHOLDERS' "
-            "and got ignored. Falling back to the default placeholder '%s'.",
-            placeholder,
-            self._placeholder,
-        )
+        if placeholder:
+            if placeholder in SQL_PLACEHOLDERS:
+                return placeholder
+            self.log.warning(
+                "Placeholder defined in Connection '%s' is not listed in 'DEFAULT_SQL_PLACEHOLDERS' "
+                "and got ignored. Falling back to the default placeholder '%s'.",
+                self.conn_name_attr,
+                self._placeholder,
+            )
         return self._placeholder
 
     def get_conn(self):

tests/providers/common/sql/hooks/test_dbapi.py

@@ -421,6 +421,56 @@ def test_get_uri_without_auth_and_empty_host(self):
         )
         assert self.db_hook.get_uri() == "conn-type://@:3306/schema?charset=utf-8"
 
+    def test_placeholder(self):
+        self.db_hook.get_connection = mock.MagicMock(
+            return_value=Connection(
+                conn_type="conn-type",
+                login=None,
+                password=None,
+                schema="schema",
+                port=3306,
+            )
+        )
+        assert self.db_hook.placeholder == "%s"
+
+        self.db_hook.log.warning.assert_not_called()
+
+    def test_placeholder_with_valid_placeholder_in_extra(self):
+        self.db_hook.get_connection = mock.MagicMock(
+            return_value=Connection(
+                conn_type="conn-type",
+                login=None,
+                password=None,
+                schema="schema",
+                port=3306,
+                extra=json.dumps({"placeholder": "?"}),
+            )
+        )
+        assert self.db_hook.placeholder == "?"
+
+        self.db_hook.log.warning.assert_not_called()
+
+    def test_placeholder_with_invalid_placeholder_in_extra(self):
+        self.db_hook.get_connection = mock.MagicMock(
+            return_value=Connection(
+                conn_type="conn-type",
+                login=None,
+                password=None,
+                schema="schema",
+                port=3306,
+                extra=json.dumps({"placeholder": "!"}),
+            )
+        )
+
+        assert self.db_hook.placeholder == "%s"
+
+        self.db_hook.log.warning.assert_called_once_with(
+            "Placeholder defined in Connection '%s' is not listed in 'DEFAULT_SQL_PLACEHOLDERS' "
+            "and got ignored. Falling back to the default placeholder '%s'.",
+            "test_conn_id",
+            self.db_hook._placeholder,
+        )
+
     def test_run_log(self):
         statement = "SQL"
         self.db_hook.run(statement)