How to route to a specific node based on tool return in LangGraph

[nimishdm-airindia]

I'm working on a chatbot using LangGraph, and I need to implement proper routing after tool execution. My setup uses a state graph with conditional edges, and I want to route to a specific node if the tool returns a goto command, otherwise route back to the main processing node.

Here's my current approach:

def route_tools_to_node(self, state: State, config: RunnableConfig):
    # TODO: If a command with goto is returned from the tool, route to that node. Otherwise route to self.name.
    return self.name

I need to modify this to check if the last tool call returned a Command with a goto field, and route accordingly.

Here's the relevant part of my graph setup code:

def build_graph(self, checkpointer=None) -> CompiledStateGraph:
    """Build the LangGraph for this workflow."""
    workflow = StateGraph(State)

    # add nodes
    workflow.add_node(self.name, self.process)
    workflow.add_node(
        "tools",
        ToolNode(self.tools),
    )
    # define edges
    workflow.set_entry_point(self.name)
    workflow.add_conditional_edges(self.name, tools_condition)
    workflow.add_conditional_edges("tools", self.route_tools_to_node)
    return workflow.compile(checkpointer=checkpointer)

For example, one of my tools returns a Command with a goto field that should end the flow:

@tool
def get_user_choice(
    state: Annotated[State, InjectedState],
    tool_call_id: Annotated[str, InjectedToolCallId],
    prompt: str,
    options: list[OptionBase],
) -> str:
    # ...implementation...
    
    return Command(
        update={
            "messages": [ToolMessage("Waiting for user input.", tool_call_id=tool_call_id)],
        },
        goto=END
    )

How can I properly implement route_tools_to_node to check if the most recent tool execution returned a Command with a goto field, and route to that node instead of always returning to the main processing node?

[Haoyuan-L]

Hi, have you solved your problem? I have a similar problem with the usage of the conditional edge. Can we use both the "goto" command and a conditional edge at the same time? Since both of them are used to route to the next node.