Fix FilterExpression to prevent incorrect matching

CHANGELOG.md

@@ -30,6 +30,7 @@
 * fix `confluent_kafka.store_offsets` if `last_valid_record` is `None`, can happen if a rebalancing happens
   before the first message was pulled.
 * fix pseudonymizer cache metrics not updated
+* fix `_get_value` in `FilterExpression` so that keys don't match on values
 * fix `auto_rule_tester` to work with `LOGPREP_BYPASS_RULE_TREE` enabled
 
 ## 14.0.0

logprep/filter/expression/filter_expression.py

@@ -87,7 +87,10 @@ def _get_value(key: List[str], document: dict) -> Any:
         for item in key:
             if item not in current:
                 raise KeyDoesNotExistError
-            current = current[item]
+            try:
+                current = current[item]
+            except TypeError as error:
+                raise KeyDoesNotExistError from error
         return current
 
     def __eq__(self, other):

tests/unit/filter/test_filter_expression.py

@@ -36,6 +36,11 @@ def test_get_value_fails_empty_key(self):
         with pytest.raises(KeyDoesNotExistError):
             FilterExpression._get_value([], {"some": "value"})
 
+    def test_get_value_fails_when_key_matches_value_instead_of_key(self):
+        document = {"key": "not_a_key"}
+        with pytest.raises(KeyDoesNotExistError):
+            FilterExpression._get_value(["key", "not_a_key"], document)
+
     def test_get_value_returns_expected_value(self):
         document = {"one": {"two": "value"}, "ten": {"eleven": "another value"}}