Described solution for issue #18

Author: anikolaienko

tests/test_issue_18_implicit_child_field_mapping.py

@@ -0,0 +1,41 @@
+from dataclasses import dataclass
+from typing import Optional
+
+from automapper import mapper
+
+
+@dataclass
+class UserDomain:
+    id: int
+    name: str
+    email: str
+
+
+@dataclass
+class TodoDomain:
+    description: str
+    user: UserDomain
+
+
+@dataclass
+class TodoModel:
+    description: str
+    user: UserDomain
+    user_id: Optional[int] = None
+
+
+def test_map__implicit_mapping_of_child_obj_field_to_parent_obj_field_not_supported():
+    user = UserDomain(id=123, name="carlo", email="mail_carlo")
+    todo = TodoDomain(description="todo_carlo", user=user)
+
+    mapper.add(TodoDomain, TodoModel)
+    todo_model: TodoModel = mapper.map(todo)
+
+    # Implicit field mapping between parent and child objects is not supported
+    # TodoDomain.user.user_id should not map to TodoModel.user_id implicitly
+    assert todo_model.user_id is None
+
+    # Workaround: use explicit mapping
+    todo_model1: TodoModel = mapper.map(todo, fields_mapping={"user_id": todo.user.id})
+
+    assert todo_model1.user_id == 123