cr

libs/core/langchain_core/load/load.py

@@ -3,6 +3,7 @@ import json
 import os
 from typing import Any, Dict, List, Optional
 
+from langchain_core.load.mapping import SERIALIZABLE_MAPPING
 from langchain_core.load.serializable import Serializable
 
 DEFAULT_NAMESPACES = ["langchain", "langchain_core", "langchain_community"]
@@ -62,8 +63,21 @@ class Reviver:
             if len(namespace) == 1 and namespace[0] == "langchain":
                 raise ValueError(f"Invalid namespace: {value}")
 
-            mod = importlib.import_module(".".join(namespace))
-            cls = getattr(mod, name)
+            # Get the importable path
+            key = tuple(namespace + [name])
+            if key not in SERIALIZABLE_MAPPING:
+                raise ValueError(
+                    "Trying to deserialize something that cannot "
+                    "be deserialized in current version of langchain-core: "
+                    f"{key}"
+                )
+            import_path = SERIALIZABLE_MAPPING[key]
+            # Split into module and name
+            import_dir, import_obj = import_path[:-1], import_path[-1]
+            # Import module
+            mod = importlib.import_module(".".join(import_dir))
+            # Import class
+            cls = getattr(mod, import_obj)
 
             # The class must be a subclass of Serializable.
             if not issubclass(cls, Serializable):