How to register type in langgraph

OSS Product Help LangGraph
1

I met this warning:
Deserializing unregistered type src.schemas.resume_models.QuestionRecord from checkpoint. This will be blocked in a future version. Add to allowed_msgpack_modules to silence: [(‘src.schemas.resume_models’, ‘QuestionRecord’)]
I used os.environ[“LANGCHAIN_ALLOWED_MSGPACK_MODULES”] = “src.schemas.resume_models” at the top of entry file of my project but no effects.
So how to elimate this warning?

versions:
langchain-core 1.2.23
langchain-openai 1.1.12
langgraph 1.1.4
langgraph-checkpoint 4.0.1
langgraph-checkpoint-sqlite 3.0.3
langgraph-prebuilt 1.0.8
langgraph-sdk 0.3.12
langsmith 0.7.23

2

hi @sog

what I can see in the source code, the env var LANGCHAIN_ALLOWED_MSGPACK_MODULES doesn’t exist. Only LANGGRAPH_STRICT_MSGPACK is read - it’s a boolean, parsed once at import time and cannot carry module names.

Try this: register types via the Python API and wire the serializer into the checkpointer:

  from langgraph.checkpoint.sqlite import SqliteSaver
  from langgraph.checkpoint.serde.jsonplus import JsonPlusSerializer
  from src.schemas.resume_models import QuestionRecord

  serde = JsonPlusSerializer(allowed_msgpack_modules=[QuestionRecord])
  checkpointer = SqliteSaver(conn, serde=serde)  # or set checkpointer.serde = serde