一个或多个用于更新图状态并向节点发送消息的命令。可用于替代条件边,将路由逻辑与状态更新结合起来。

示例

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

// Define graph state
const StateAnnotation = Annotation.Root({
foo: Annotation<string>,
});

// Define the nodes
const nodeA = async (_state: typeof StateAnnotation.State) => {
console.log("Called A");
// this is a replacement for a real conditional edge function
const goto = Math.random() > .5 ? "nodeB" : "nodeC";
// note how Command allows you to BOTH update the graph state AND route to the next node
return new Command({
// this is the state update
update: {
foo: "a",
},
// this is a replacement for an edge
goto,
});
};

// Nodes B and C are unchanged
const nodeB = async (state: typeof StateAnnotation.State) => {
console.log("Called B");
return {
foo: state.foo + "|b",
};
}

const nodeC = async (state: typeof StateAnnotation.State) => {
console.log("Called C");
return {
foo: state.foo + "|c",
};
}

import { StateGraph } from "@langchain/langgraph";

// NOTE: there are no edges between nodes A, B and C!
const graph = new StateGraph(StateAnnotation)
.addNode("nodeA", nodeA, {
ends: ["nodeB", "nodeC"],
})
.addNode("nodeB", nodeB)
.addNode("nodeC", nodeC)
.addEdge("__start__", "nodeA")
.compile();

await graph.invoke({ foo: "" });

// Randomly oscillates between
// { foo: 'a|c' } and { foo: 'a|b' }

类型参数

  • R = unknown

构造函数

属性

goto?: string | Send | (string | Send)[]

可以是以下任意一种:

  • 要导航到的下一个节点的名称(属于指定 graph 的任何节点)
  • 要导航到的下一个节点名称序列
  • Send 对象(使用 Send 对象中提供的精确输入执行节点)
  • Send 对象序列
graph?: string

发送命令到的图。支持的值包括:

  • None:当前图(默认)
  • 发送命令到的图的具体名称
  • Command.PARENT:最近的父图(仅在从子图中的节点返回时支持)
lc_direct_tool_output: boolean
lg_name: "Command" = "Command"
resume?: R

用于恢复执行的值。与 interrupt 一起使用。

update?: Record<string, unknown> | [string, unknown][]

应用于图状态的更新,作为执行返回此命令的节点的结果。写入状态时,就像节点直接返回此值而不是 Command 对象一样。

PARENT: string

方法

  • 返回 {
        goto: undefined | string | {
            args: any;
            lg_name: string;
            node: string;
        } | (string | {
            args: any;
            lg_name: string;
            node: string;
        })[];
        lg_name: string;
        resume: undefined | R;
        update: undefined | Record<string, unknown> | [string, unknown][];
    }

    • goto: undefined | string | {
          args: any;
          lg_name: string;
          node: string;
      } | (string | {
          args: any;
          lg_name: string;
          node: string;
      })[]
    • lg_name: string
    • resume: undefined | R
    • update: undefined | Record<string, unknown> | [string, unknown][]