Assign copy of new field which is created in lookup

aggify/aggify.py

@@ -22,6 +22,7 @@
     convert_match_query,
     check_field_already_exists,
     get_db_field,
+    copy_class,
 )
 
 AggifyType = TypeVar("AggifyType", bound=Callable[..., "Aggify"])
@@ -56,9 +57,7 @@ def __init__(self, base_model: Type[Document]):
             base_model: The base model class.
         """
         # Create a separate copy of the main class for safety and flexibility
-        self.base_model = type(
-            "Aggify_base_model", base_model.__bases__, dict(base_model.__dict__)
-        )
+        self.base_model = copy_class(base_model)
         self.pipelines: List[Dict[str, Union[dict, Any]]] = []
         self.start = None
         self.stop = None
@@ -656,7 +655,7 @@ def lookup(
         self.pipelines.append(lookup_stage)
 
         # Add this new field to base model fields, which we can use it in the next stages.
-        self.base_model._fields[as_name] = from_collection  # noqa
+        self.base_model._fields[as_name] = copy_class(from_collection)  # noqa
 
         return self
 

aggify/utilty.py

@@ -168,3 +168,22 @@ def get_nested_field_model(model: CollectionType, field: str) -> CollectionType:
     if model._fields[field].__dict__.get("__module__"):  # noqa
         return model
     return model._fields[field].__dict__["document_type_obj"]  # noqa
+
+
+def copy_class(original_class):
+    """
+    Copies a class, creating a new class with the same bases and attributes.
+
+    Parameters:
+    original_class (class): The class to be copied.
+
+    Returns:
+    class: A new class with the same bases and attributes as the original class.
+    """
+    # Create a new class with the same name, bases, and attributes
+    copied_class = type(
+        "Aggify" + original_class.__name__,
+        original_class.__bases__,
+        dict(original_class.__dict__),
+    )
+    return copied_class