Zyp/Moksha: Improve error reporting when rule evaluation fails

Author: amotl

CHANGES.md

@@ -2,6 +2,7 @@
 
 ## Unreleased
 - DynamoDB CDC: Fix `MODIFY` operation by propagating `NewImage` fully
+- Zyp/Moksha: Improve error reporting when rule evaluation fails
 
 ## 2024/09/25 v0.0.18
 - MongoDB: Improved `MongoDBCrateDBConverter.decode_canonical` to also

src/zyp/model/moksha.py

@@ -78,6 +78,8 @@ def apply(self, data: t.Any) -> t.Any:
                 data = rule.evaluate(data)
             except Exception:
                 logger.exception(f"Error evaluating rule: {rule}")
+                if isinstance(data, map):
+                    data = list(data)
                 logger.debug(f"Error payload:\n{data}")
                 raise
         return data

tests/zyp/moksha/test_model.py

@@ -49,7 +49,7 @@ def test_moksha_transformation_success_jq():
     assert moksha.apply(4242) == 42.42
 
 
-def test_moksha_transformation_error_jq(caplog):
+def test_moksha_transformation_error_jq_scalar(caplog):
     moksha = MokshaTransformation().jq(". /= 100")
     with pytest.raises(ValueError) as ex:
         moksha.apply("foo")
@@ -59,6 +59,16 @@ def test_moksha_transformation_error_jq(caplog):
     assert "Error payload:\nfoo" in caplog.messages
 
 
+def test_moksha_transformation_error_jq_map(caplog):
+    moksha = MokshaTransformation().jq(".foo")
+    with pytest.raises(ValueError) as ex:
+        moksha.apply(map(lambda x: x, ["foo"]))  # noqa: C417
+    assert ex.match(re.escape('Cannot index array with string "foo"'))
+
+    assert "Error evaluating rule: MokshaRuntimeRule(type='jq'" in caplog.text
+    assert "Error payload:\n[]" in caplog.messages
+
+
 def test_moksha_transformation_empty():
     """
     Empty JSON Pointer expression means "root node".