OpenAI function calling 实践-工具盒子

OpenAI 的 function calling 是什么？

function calling 即函数调用，是 OpenAI 引入的一项功能，可以增强模型在执行特定任务时的能力。这项功能允许模型在对话过程中调用预定义的函数，完成特定的任务或获取外部系统的信息。这种功能使模型不仅能生成文本，还能通过调用外部函数执行操作，扩展其能力。

OpenAI 的模型在无 function calling 时存在的不足？

无法自动执行某些变成或者工具调用，例如自动化的数据处理、API 调用、数据库查询等，导致需要手动执行操作，增加了工作量。
无法获取实时信息，如当前的天气、股票价格、最近的新闻等，导致提供了过时的信息。
无法获取特定领域的知识，如专业领域的医学知识、金融知识、法律知识，导致无法准确地回答一些专业性很强的问题。

总的来说，function calling 增强了模型在处理复杂任务、精确性、实时性和用户交互等方面的能力，缺乏这一功能将限制模型在这些领域的表现。

无函数调用时对话处理过程 {#1-无函数调用时对话处理过程}

无函数调用的时候，对话处理过程如下：

Client 发送请求到 Chat Server
Chat Server 发送 Prompt 给 OpenAI Server
OpenAI Server 响应文本给 Chat Server
Chat Server 将响应结果返回给用户
重复执行

首次请求如下：

|-----------------------|-----------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 | { "messages": [ { "role": "user", "content": "今天天气怎么样？" } ], "model": "gpt-4o", "stream": false } |

再次请求如下：

|---------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 9 | { "messages": [ { "role": "user", "content": "今天天气怎么样？" }, { "role": "assistant", "content": "很抱歉，我无法实时获取天气信息。" }, { "role": "user", "content": "北京今天天气怎么样？" } ], "model": "gpt-4o", "stream": false } |

实现的 nextjs 代码如下：

|------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | import { NextApiRequest, NextApiResponse } from 'next' export default async function createMessage(req: NextApiRequest, res: NextApiResponse) { const { messages } = req.body const apiKey = process.env.OPENAI_API_KEY // https://api.openai.com/v1 const baseUrl = process.env.OPENAI_BASE_URL // sk-xxx const body = JSON.stringify({ messages, model: 'gpt-4o', stream: false }) try { const response = await fetch(`${baseUrl}/chat/completions`, { method: 'POST', headers: { 'Content-Type': 'application/json', Authorization: `Bearer ${apiKey}`, }, body }) const data = await response.json() res.status(200).json({ data }) } catch (error: any) { res.status(500).json({ error: error.message }) } } |

有函数调用时对话处理过程 {#2-有函数调用时对话处理过程}

有函数调用的时候，对话处理过程如下：

Client 发送 user prompt 到 Chat Server
Chat Server 将用户提示词和函数定义一并发送给 OpenAI Server
OpenAI Server 根据用户的提示词，判断是用普通文本响应还是函数调用的格式响应
如果是函数调用则返回调用的函数名及参数，Chat Server 执行该函数，并将结果再次发送给 OpenAI
如果需要调用多个函数，则重复执行 3-4 步
OpenAI Server 根据提供的数据，使用普通文本响应

首次请求如下：

|------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | { "messages": [ { "role": "user", "content": "今天天气怎么样？" } ], "model": "gpt-4o", "stream": false, "tools": [ { "type": "function", "function": { "name": "getLocation", "description": "Get the user's current location", "parameters": { "type": "object", "properties": {}, "required": [] } } }, { "type": "function", "function": { "name": "getCurrentWeather", "description": "Get the current weather for a location", "parameters": { "type": "object", "properties": { "latitude": { "type": "number" }, "longitude": { "type": "number" } }, "required": ["latitude", "longitude"] } } } ], "tool_choice": "auto" } |

再次请求如下（携带位置信息）：

|---------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 | { "messages": [ { "role": "user", "content": "今天天气怎么样？" }, { "role": "function", "name": "getLocation", "content": "{\n \"latitude\": 40.7128,\n \"longitude\": -74.006\n}" } ], "model": "gpt-4o", "stream": false, "tools": [ { "type": "function", "function": { "name": "getLocation", "description": "Get the user's current location", "parameters": { "type": "object", "properties": {}, "required": [] } } }, { "type": "function", "function": { "name": "getCurrentWeather", "description": "Get the current weather for a location", "parameters": { "type": "object", "properties": { "latitude": { "type": "number" }, "longitude": { "type": "number" } }, "required": ["latitude", "longitude"] } } } ], "tool_choice": "auto" } |

最后一次请求如下（携带位置和天气信息）：

|------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 | { "messages": [ { "role": "user", "content": "今天天气怎么样？" }, { "role": "function", "name": "getLocation", "content": "{\n \"latitude\": 40.7128,\n \"longitude\": -74.006\n}" }, { "role": "function", "name": "getCurrentWeather", "content": "{\n \"temperature\": 22,\n \"condition\": \"sunny\"\n}" } ], "model": "gpt-4o", "stream": false, "tools": [ { "type": "function", "function": { "name": "getLocation", "description": "Get the user's current location", "parameters": { "type": "object", "properties": {}, "required": [] } } }, { "type": "function", "function": { "name": "getCurrentWeather", "description": "Get the current weather for a location", "parameters": { "type": "object", "properties": { "latitude": { "type": "number" }, "longitude": { "type": "number" } }, "required": ["latitude", "longitude"] } } } ], "tool_choice": "auto" } |

实现的 nextjs 代码如下：

|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------| | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 | import { NextApiRequest, NextApiResponse } from 'next' export default async function createMessage(req: NextApiRequest, res: NextApiResponse) { const { messages } = req.body const apiKey = process.env.OPENAI_API_KEY const baseUrl = process.env.OPENAI_BASE_URL try { while (true) { const body = JSON.stringify({ messages, model: 'openai/gpt-4o-2024-08-06', stream: false, tools: functions, tool_choice: 'auto' }) const response = await fetch(`${baseUrl}/chat/completions`, { method: 'POST', headers: { 'Content-Type': 'application/json', Authorization: `Bearer ${apiKey}` }, body }) const data = await response.json() const { finish_reason, message } = data.choices[0] if (finish_reason === 'tool_calls') { const functionName = message.tool_calls[0].function.name const fucntionArguments = message.tool_calls[0].function.arguments const functionArgsArr = Object.values(fucntionArguments) const functionToCall = availableFunctions[functionName] const functionResponse = await functionToCall.apply(null, functionArgsArr) messages.push({ role: 'function', name: functionName, content: `${JSON.stringify(functionResponse, null, 2)}` }) } else if (finish_reason === 'stop') { res.status(200).json({ data }) return } } } catch (error: any) { res.status(500).json({ error: error.message }) } } async function getLocation() { return { latitude: 40.7128, longitude: -74.0060 } } async function getCurrentWeather(latitude: any, longitude: any) { return { temperature: 22, condition: "sunny" } } const functions = [ { type: 'function', function: { name: 'getLocation', description: "Get the user's current location", parameters: { type: 'object', properties: {}, required: [] } } }, { type: 'function', function: { name: 'getCurrentWeather', description: 'Get the current weather for a location', parameters: { type: 'object', properties: { latitude: { type: 'number' }, longitude: { type: 'number' } }, required: ['latitude', 'longitude'] } } } ] const availableFunctions = { getCurrentWeather, getLocation } |

完整的代码：nextjs-chatgpt-tutorial

3.问题 {#3问题}

GPT 大模型如何知道获取天气需要调用 getLocation() 和 getCurrentWeather() 函数的？

自然语言理解能力：通过对用户输入"今天天气怎么样？"的理解，知道用户想要获取天气信息。
上下文分析：模型分析了所有的请求上下文，包括可用的工具函数。它理解了 getLocation() 和 getCurrentWeather() 函数的功能和参数。
任务分解：模型将"获取天气"任务分解为两个步骤：首先获取位置，然后根据位置获取天气。
工具选择能力：模型基于对任务的理解，选择了最适合的工具组合来完成任务。
参数依赖分析：模型分析到 getCurrentWeather() 函数需要经度和纬度作为输入，而 getLocation 函数刚好可以提供。因此，它推断出需要现调用 getLocation()，再调用 getCurrentWeather()。
训练数据中的模式：模型训练过类似的场景，学习到了处理天气查询时常用的步骤和工具组合。
推理能力：基于以上所有信息，模型推理后得出需要依次调用这两个函数才能回答用户的问题。