| Name | Type | Description |
|---|---|---|
node* | str | The name of the target node to send the message to. |
arg* | Any | The state or message to send to the target node. |
timeout | float | timedelta | TimeoutPolicy | None | Default: None |
| Name | Type |
|---|---|
| node | str |
| arg | Any |
| timeout | float | timedelta | TimeoutPolicy | None |
A message or packet to send to a specific node in the graph.
The Send class is used within a StateGraph's conditional edges to
dynamically invoke a node with a custom state at the next step.
Importantly, the sent state can differ from the core graph's state, allowing for flexible and dynamic workflow management.
One such example is a "map-reduce" workflow where your graph invokes the same node multiple times in parallel with different states, before aggregating the results back into the main graph's state.
from typing import Annotated
from langgraph.types import Send
from langgraph.graph import END, START
from langgraph.graph import StateGraph
import operator
class OverallState(TypedDict):
subjects: list[str]
jokes: Annotated[list[str], operator.add]
def continue_to_jokes(state: OverallState):
return [Send("generate_joke", {"subject": s}) for s in state["subjects"]]
builder = StateGraph(OverallState)
builder.add_node("generate_joke", lambda state: {"jokes": [f"Joke about {state['subject']}"]})
builder.add_conditional_edges(START, continue_to_jokes)
builder.add_edge("generate_joke", END)
graph = builder.compile()
# Invoking with two subjects results in a generated joke for each
graph.invoke({"subjects": ["cats", "dogs"]})
# {'subjects': ['cats', 'dogs'], 'jokes': ['Joke about cats', 'Joke about dogs']}Optional timeout policy for this specific pushed task. A
number or timedelta is treated as a hard run_timeout.
