类 Send<Node, Args>

发送到图中特定节点的消息或数据包。

Send 类在 StateGraph 的条件边中使用，用于在下一步中使用自定义状态动态调用节点。

重要的是，发送的状态可以与图的核心状态不同，从而实现灵活和动态的工作流管理。

一个典型的例子是“map-reduce”工作流，其中您的图使用不同的状态并行多次调用同一个节点，然后将结果聚合回主图的状态。

示例

import { Annotation, Send, StateGraph } from "@langchain/langgraph";

const ChainState = Annotation.Root({
  subjects: Annotation<string[]>,
  jokes: Annotation<string[]>({
    reducer: (a, b) => a.concat(b),
  }),
});

const continueToJokes = async (state: typeof ChainState.State) => {
  return state.subjects.map((subject) => {
    return new Send("generate_joke", { subjects: [subject] });
  });
};

const graph = new StateGraph(ChainState)
  .addNode("generate_joke", (state) => ({
    jokes: [`Joke about ${state.subjects}`],
  }))
  .addConditionalEdges("__start__", continueToJokes)
  .addEdge("generate_joke", "__end__")
  .compile();

const res = await graph.invoke({ subjects: ["cats", "dogs"] });
console.log(res);

// Invoking with two subjects results in a generated joke for each
// { subjects: ["cats", "dogs"], jokes: [`Joke about cats`, `Joke about dogs`] }
Copy