Skip recursive map_object for scalars with no range

src/linkml_map/transformer/object_transformer.py

@@ -596,6 +596,11 @@ def _map_value_by_range(
                 if source_class_slot.multivalued and isinstance(v, list):
                     return [self.transform_enum(v1, any_of_enums, source_obj) for v1 in v]
                 return self.transform_enum(v, any_of_enums, source_obj)
+            # No range and no any_of enums: nothing to recurse into for scalars
+            if not isinstance(v, (dict, list)):
+                return v
+            if isinstance(v, list) and all(not isinstance(v1, (dict, list)) for v1 in v):
+                return v
 
         if source_class_slot.multivalued:
             if isinstance(v, list):

tests/test_transformer/test_no_range_scalar.py

@@ -0,0 +1,90 @@
+"""Regression test: scalar slots with no explicit range should not emit warnings.
+
+When a source slot has no range (and no default_range), _map_value_by_range
+should short-circuit for scalar and multivalued scalar values instead of
+falling through to map_object, which would log "Unexpected: <value>" warnings.
+
+See: https://github.com/linkml/linkml-map/pull/173
+"""
+
+import textwrap
+
+from linkml_runtime import SchemaView
+
+from linkml_map.transformer.object_transformer import ObjectTransformer
+
+SOURCE_SCHEMA = textwrap.dedent("""\
+    id: https://example.org/source
+    name: source
+    prefixes:
+      linkml: https://w3id.org/linkml/
+    imports:
+      - linkml:types
+
+    classes:
+      Record:
+        attributes:
+          id:
+            identifier: true
+          tag: {}
+          tags:
+            multivalued: true
+""")
+
+TARGET_SCHEMA = textwrap.dedent("""\
+    id: https://example.org/target
+    name: target
+    prefixes:
+      linkml: https://w3id.org/linkml/
+    imports:
+      - linkml:types
+
+    classes:
+      Output:
+        attributes:
+          id: {}
+          tag: {}
+          tags:
+            multivalued: true
+""")
+
+
+def _make_transformer() -> ObjectTransformer:
+    """Build a transformer with schemas that have slots without explicit ranges."""
+    transform = {
+        "source_schema": "https://example.org/source",
+        "target_schema": "https://example.org/target",
+        "class_derivations": {
+            "Output": {
+                "populated_from": "Record",
+                "slot_derivations": {
+                    "id": {"populated_from": "id"},
+                    "tag": {"populated_from": "tag"},
+                    "tags": {"populated_from": "tags"},
+                },
+            }
+        },
+    }
+    tr = ObjectTransformer()
+    tr.source_schemaview = SchemaView(SOURCE_SCHEMA)
+    tr.target_schemaview = SchemaView(TARGET_SCHEMA)
+    tr.create_transformer_specification(transform)
+    return tr
+
+
+def test_scalar_no_range_no_warning(caplog):
+    """Mapping a scalar slot with no range should not emit an 'Unexpected' warning."""
+    tr = _make_transformer()
+    result = tr.map_object({"id": "r1", "tag": "important"}, "Record")
+
+    assert result["tag"] == "important"
+    assert "Unexpected" not in caplog.text
+
+
+def test_multivalued_scalar_no_range_no_warning(caplog):
+    """Mapping a multivalued scalar slot with no range should not emit an 'Unexpected' warning."""
+    tr = _make_transformer()
+    result = tr.map_object({"id": "r1", "tags": ["a", "b", "c"]}, "Record")
+
+    assert result["tags"] == ["a", "b", "c"]
+    assert "Unexpected" not in caplog.text