Default state value idea

[bluemeat0724]

Are there good ways to manupulate state value.

Here is what I tried to set up default state:

class GraphState(BaseModel):
sys_msg: Optional[str] = 'You are a helpful assistant'
messages: Annotated[list[AnyMessage], add_messages]

def node(state: GraphState):
return {"messages": [{'role':"user","content":"just add something",'name':'G'}]}

builder = StateGraph(GraphState)
builder.add_node(node)
builder.add_edge(START, "node")
builder.add_edge("node", END)
graph = builder.compile()

graph.invoke({"messages": "hello"})

expect:

{'sys_msg': 'You are a helpful assistant',
'messages': [HumanMessage(content='hello', additional_kwargs={}, response_metadata={}, id='5aa8a2b4-77c3-46df-b2c5-14adc3ca3d54'),
HumanMessage(content='just add something', additional_kwargs={}, response_metadata={}, name='G', id='888011a5-8ca7-4ebf-aed1-fe88f096adbc')]}

got:
{'messages': [HumanMessage(content='hello', additional_kwargs={}, response_metadata={}, id='76912a86-3ffb-4e92-9e3d-2cb77a6430fc'),
HumanMessage(content='just add something', additional_kwargs={}, response_metadata={}, name='G', id='eaf45e81-0067-45e6-b58f-c65bb180e41f')]}

[bluemeat0724]

I was hoping to incorporate more logic into the Pydantic model. Will such features be supported in the future?

[vbarda]

@bluemeat0724 you can achieve your desired behavior by passing Pydantic model into the graph.invoke:

graph.invoke(GraphState(messages=[{'type':"human", "content": "hello"}]))

Note that your default value of sys_msg is also available as part of the state dict inside the node function (even if you invoke the graph with a dict input)

hope this helps!