community[patch]: Databricks SerDe uses cloudpickle instead of pickle (…

…langchain-ai#18607)

- **Description:** Databricks SerDe uses cloudpickle instead of pickle
when serializing a user-defined function transform_input_fn since pickle
does not support functions defined in `__main__`, and cloudpickle
supports this.
- **Dependencies:** cloudpickle>=2.0.0

Added a unit test.

libs/community/langchain_community/llms/databricks.py

@@ -1,5 +1,4 @@
 import os
-import pickle
 import re
 import warnings
 from abc import ABC, abstractmethod
@@ -225,7 +224,12 @@ def _is_hex_string(data: str) -> bool:
 def _load_pickled_fn_from_hex_string(data: str) -> Callable:
     """Loads a pickled function from a hexadecimal string."""
     try:
-        return pickle.loads(bytes.fromhex(data))
+        import cloudpickle
+    except Exception as e:
+        raise ValueError(f"Please install cloudpickle>=2.0.0. Error: {e}")
+
+    try:
+        return cloudpickle.loads(bytes.fromhex(data))
     except Exception as e:
         raise ValueError(
             f"Failed to load the pickled function from a hexadecimal string. Error: {e}"
@@ -235,7 +239,12 @@ def _load_pickled_fn_from_hex_string(data: str) -> Callable:
 def _pickle_fn_to_hex_string(fn: Callable) -> str:
     """Pickles a function and returns the hexadecimal string."""
     try:
-        return pickle.dumps(fn).hex()
+        import cloudpickle
+    except Exception as e:
+        raise ValueError(f"Please install cloudpickle>=2.0.0. Error: {e}")
+
+    try:
+        return cloudpickle.dumps(fn).hex()
     except Exception as e:
         raise ValueError(f"Failed to pickle the function: {e}")
 

libs/community/pyproject.toml

@@ -81,6 +81,7 @@ hologres-vector = {version = "^0.0.6", optional = true}
 praw = {version = "^7.7.1", optional = true}
 msal = {version = "^1.25.0", optional = true}
 databricks-vectorsearch = {version = "^0.21", optional = true}
+cloudpickle = {version = ">=2.0.0", optional = true}
 dgml-utils = {version = "^0.3.0", optional = true}
 datasets = {version = "^2.15.0", optional = true}
 tree-sitter = {version = "^0.20.2", optional = true}
@@ -249,6 +250,7 @@ extended_testing = [
  "hologres-vector",
  "praw",
  "databricks-vectorsearch",
+ "cloudpickle",
  "dgml-utils",
  "cohere",
  "tree-sitter",
@@ -260,7 +262,8 @@ extended_testing = [
  "elasticsearch",
  "hdbcli",
  "oci",
- "rdflib"
+ "rdflib",
+ "cloudpickle",
 ]
 
 [tool.ruff]

libs/community/tests/unit_tests/llms/test_databricks.py

@@ -1,10 +1,13 @@
 """test Databricks LLM"""
-import pickle
 from typing import Any, Dict
 
+import pytest
 from pytest import MonkeyPatch
 
-from langchain_community.llms.databricks import Databricks
+from langchain_community.llms.databricks import (
+    Databricks,
+    _load_pickled_fn_from_hex_string,
+)
 
 
 class MockDatabricksServingEndpointClient:
@@ -29,7 +32,10 @@ def transform_input(**request: Any) -> Dict[str, Any]:
     return request
 
 
+@pytest.mark.requires("cloudpickle")
 def test_serde_transform_input_fn(monkeypatch: MonkeyPatch) -> None:
+    import cloudpickle
+
     monkeypatch.setattr(
         "langchain_community.llms.databricks._DatabricksServingEndpointClient",
         MockDatabricksServingEndpointClient,
@@ -42,5 +48,9 @@ def test_serde_transform_input_fn(monkeypatch: MonkeyPatch) -> None:
         transform_input_fn=transform_input,
     )
     params = llm._default_params
-    pickled_string = pickle.dumps(transform_input).hex()
+    pickled_string = cloudpickle.dumps(transform_input).hex()
     assert params["transform_input_fn"] == pickled_string
+
+    request = {"prompt": "What is the meaning of life?"}
+    fn = _load_pickled_fn_from_hex_string(params["transform_input_fn"])
+    assert fn(**request) == transform_input(**request)