Node.js中使用OpenAI GPT-4o API实现本地图片OCR报错求助

问题重现 #

尝试用Node.js调用OpenAI的GPT-4O实现本地图片OCR，编写的代码如下：

const api_key = "mykey"
import OpenAI from 'openai';
import fs from "fs"

const openai = new OpenAI({
    apiKey: api_key, 
});

function convertToBase64(filePath) {
    const bitmap = fs.readFileSync(filePath);
    return Buffer.from(bitmap).toString('base64');
}

(async () => {
    const chatCompletion = await openai.chat.completions.create({
        model: "gpt-4o",
        messages: [
            {
                content: [
                    {
                        role: 'user',
                        content: 'Return me the text of this image.'
                    },
                    {
                        role: 'system',
                        content: 'image_url',
                        image_url: `data:image/png;base64${convertToBase64('./image12.png')}`
                    }
                ]
            }

        ]
    });

    console.log(chatCompletion.choices[0].message.content);

})();

运行后出现错误：

(node:23388) [DEP0040] DeprecationWarning: The punycode module is
deprecated. Please use a userland alternative instead. (Use node --trace-deprecation ... to show where the warning was created) url-state-machine.js:2 Uncaught BadRequestError Error: 400 Invalid
chat format. Expected 'role' fields in all messages.
at generate (path\node_modules\openai\error.mjs:41:20)
at makeStatusError (path\node_modules\openai\core.mjs:268:25)
at makeRequest (path\node_modules\openai\core.mjs:311:30)
at processTicksAndRejections (internal/process/task_queues:95:5) error.mjs:41 Process exited with code 1

错误原因 #

代码存在3个关键格式问题，不符合OpenAI多模态API的要求：

• 消息结构错误：外层消息对象缺少role字段，且错误地将不同角色的内容嵌套在同一个content数组中。多模态消息应是单个角色（通常为user）的content数组，包含文本和图片元素。
• 图片URL格式错误：Base64前缀data:image/png;base64后缺少逗号，正确格式应为data:image/png;base64,。
• 图片内容格式错误：图片元素需要指定type: "image_url"，并将图片URL放在image_url对象的url字段中，而非直接写image_url属性。

修正后的代码 #

const api_key = "mykey";
import OpenAI from 'openai';
import fs from "fs";

const openai = new OpenAI({
    apiKey: api_key, 
});

function convertToBase64(filePath) {
    const bitmap = fs.readFileSync(filePath);
    return Buffer.from(bitmap).toString('base64');
}

(async () => {
    try {
        const chatCompletion = await openai.chat.completions.create({
            model: "gpt-4o",
            messages: [
                {
                    role: "user", // 外层消息必须指定角色
                    content: [
                        {
                            type: "text", // 文本内容需指定类型
                            text: "Return me the text of this image."
                        },
                        {
                            type: "image_url", // 图片内容指定类型为image_url
                            image_url: {
                                url: `data:image/png;base64,${convertToBase64('./image12.png')}` // 修复Base64格式，添加逗号
                            }
                        }
                    ]
                }
            ]
        });

        console.log(chatCompletion.choices[0].message.content);
    } catch (error) {
        console.error("调用失败:", error);
    }
})();

额外说明 #

• 关于punycode模块的 deprecation warning：这是依赖库内部的问题，不影响功能，可忽略或更新OpenAI SDK版本解决。
• 确保图片路径正确，且图片格式与URL中指定的image/png一致（如果是JPG则改为image/jpeg）。

内容的提问来源于stack exchange，提问作者Pipo