如何同时配置多种流式处理模式

本指南介绍如何同时配置多种流式处理模式。

设置

首先，我们需要安装所需的软件包

npm install @langchain/langgraph @langchain/openai @langchain/core

接下来，我们需要为 OpenAI（我们将使用的 LLM）设置 API 密钥

export OPENAI_API_KEY=your-api-key

可选地，我们可以为 LangSmith 追踪设置 API 密钥，这将为我们提供一流的可观察性。

export LANGCHAIN_TRACING_V2="true"
export LANGCHAIN_CALLBACKS_BACKGROUND="true"
export LANGCHAIN_API_KEY=your-api-key

定义图

在本指南中，我们将使用预构建的 ReAct 代理。

import { ChatOpenAI } from "@langchain/openai";
import { tool } from '@langchain/core/tools';
import { z } from 'zod';
import { createReactAgent } from "@langchain/langgraph/prebuilt";

const model = new ChatOpenAI({
    model: "gpt-4o",
  });

const getWeather = tool((input) => {
  if (["sf", "san francisco", "san francisco, ca"].includes(input.location.toLowerCase())) {
    return "It's 60 degrees and foggy.";
  } else {
    return "It's 90 degrees and sunny.";
  }
}, {
  name: "get_weather",
  description: "Call to get the current weather.",
  schema: z.object({
    location: z.string().describe("Location to get the weather for."),
  })
})

const graph = createReactAgent({ llm: model, tools: [getWeather] });

流式传输多种模式

要获取多种类型的流式块，请在 .stream() 的第二个参数中，在 streamMode 键下传递一个值数组

let inputs = { messages: [{ role: "user", content: "what's the weather in sf?" }] };

let stream = await graph.stream(inputs, {
  streamMode: ["updates", "debug"],
});

for await (const chunk of stream) {
  console.log(`Receiving new event of type: ${chunk[0]}`);
  console.log(chunk[1]);
  console.log("\n====\n");
}

Receiving new event of type: debug
{
  type: 'task',
  timestamp: '2024-08-30T20:58:58.404Z',
  step: 1,
  payload: {
    id: '768110dd-6004-59f3-8671-6ca699cccd71',
    name: 'agent',
    input: { messages: [Array] },
    triggers: [ 'start:agent' ],
    interrupts: []
  }
}

====

Receiving new event of type: updates
{
  agent: {
    messages: [
      AIMessage {
        "id": "chatcmpl-A22zqTwumhtW8TMjQ1FxlzCEMBk0R",
        "content": "",
        "additional_kwargs": {
          "tool_calls": [
            {
              "id": "call_HAfilebE1q9E9OQHOlL3JYHP",
              "type": "function",
              "function": "[Object]"
            }
          ]
        },
        "response_metadata": {
          "tokenUsage": {
            "completionTokens": 15,
            "promptTokens": 59,
            "totalTokens": 74
          },
          "finish_reason": "tool_calls",
          "system_fingerprint": "fp_157b3831f5"
        },
        "tool_calls": [
          {
            "name": "get_weather",
            "args": {
              "location": "San Francisco"
            },
            "type": "tool_call",
            "id": "call_HAfilebE1q9E9OQHOlL3JYHP"
          }
        ],
        "invalid_tool_calls": [],
        "usage_metadata": {
          "input_tokens": 59,
          "output_tokens": 15,
          "total_tokens": 74
        }
      }
    ]
  }
}

====

Receiving new event of type: debug
{
  type: 'task_result',
  timestamp: '2024-08-30T20:58:59.072Z',
  step: 1,
  payload: {
    id: '768110dd-6004-59f3-8671-6ca699cccd71',
    name: 'agent',
    result: [ [Array] ]
  }
}

====

Receiving new event of type: debug
{
  type: 'task',
  timestamp: '2024-08-30T20:58:59.074Z',
  step: 2,
  payload: {
    id: '76459c18-5621-5893-9b93-13bc1db3ba6d',
    name: 'tools',
    input: { messages: [Array] },
    triggers: [ 'branch:agent:shouldContinue:tools' ],
    interrupts: []
  }
}

====

Receiving new event of type: updates
{
  tools: {
    messages: [
      ToolMessage {
        "content": "It's 60 degrees and foggy.",
        "name": "get_weather",
        "additional_kwargs": {},
        "response_metadata": {},
        "tool_call_id": "call_HAfilebE1q9E9OQHOlL3JYHP"
      }
    ]
  }
}

====

Receiving new event of type: debug
{
  type: 'task_result',
  timestamp: '2024-08-30T20:58:59.076Z',
  step: 2,
  payload: {
    id: '76459c18-5621-5893-9b93-13bc1db3ba6d',
    name: 'tools',
    result: [ [Array] ]
  }
}

====

Receiving new event of type: debug
{
  type: 'task',
  timestamp: '2024-08-30T20:58:59.077Z',
  step: 3,
  payload: {
    id: '565d8a53-1057-5d83-bda8-ba3fada24b70',
    name: 'agent',
    input: { messages: [Array] },
    triggers: [ 'tools' ],
    interrupts: []
  }
}

====

Receiving new event of type: updates
{
  agent: {
    messages: [
      AIMessage {
        "id": "chatcmpl-A22zrdeobsBzkiES0C6Twh3p7I344",
        "content": "The weather in San Francisco right now is 60 degrees and foggy.",
        "additional_kwargs": {},
        "response_metadata": {
          "tokenUsage": {
            "completionTokens": 16,
            "promptTokens": 90,
            "totalTokens": 106
          },
          "finish_reason": "stop",
          "system_fingerprint": "fp_157b3831f5"
        },
        "tool_calls": [],
        "invalid_tool_calls": [],
        "usage_metadata": {
          "input_tokens": 90,
          "output_tokens": 16,
          "total_tokens": 106
        }
      }
    ]
  }
}

====

Receiving new event of type: debug
{
  type: 'task_result',
  timestamp: '2024-08-30T20:58:59.640Z',
  step: 3,
  payload: {
    id: '565d8a53-1057-5d83-bda8-ba3fada24b70',
    name: 'agent',
    result: [ [Array] ]
  }
}

====