NodeJS 在自定义API中返回随机图像时出现问题

6rvt4ljy 于 2023-02-03 发布在 Node.js

关注(0)|答案(2)|浏览(111)

使用Express和Node JS，我正在做一个返回随机猫图像的东西。但是，我在下面的代码中遇到了一些问题，正在寻找解决方案。

app.get("/media/funnycats", (req, res, next) => {
    let file = Math.floor(Math.random()*catarray.length)
        let fileurl = catarray[file]
        let fileimg = fetch(fileurl)
    let img = Buffer.from(fileimg, 'base64');
    res.writeHead(200, {
        'Content-Type': 'image/png',
        'Content-Length': img.length
    });
    res.end(img); 
});

我的目标是得到一个随机的猫图像回来，他们都在pngs和链接到cdn。错误我不断得到下面列出，我有麻烦解决它：

TypeError [ERR_INVALID_ARG_TYPE]: The first argument must be of type string or an instance of Buffer, ArrayBuffer, or Array or an Array-like Object. Received an instance of Promise
    at Function.from (buffer.js:330:9)
    at /home/runner/api/index.js:21:22
    at Layer.handle [as handle_request] (/home/runner/api/node_modules/express/lib/router/layer.js:95:5)
    at next (/home/runner/api/node_modules/express/lib/router/route.js:137:13)
    at Route.dispatch (/home/runner/api/node_modules/express/lib/router/route.js:112:3)
    at Layer.handle [as handle_request] (/home/runner/api/node_modules/express/lib/router/layer.js:95:5)
    at /home/runner/api/node_modules/express/lib/router/index.js:281:22
    at Function.process_params (/home/runner/api/node_modules/express/lib/router/index.js:335:12)
    at next (/home/runner/api/node_modules/express/lib/router/index.js:275:10)
    at expressInit (/home/runner/api/node_modules/express/lib/middleware/init.js:40:5)

我使用的是node.js项目，不知道在这种情况下会出现什么问题。

node.js

来源：https://stackoverflow.com/questions/70087178/trouble-w-returning-random-image-in-my-custom-api

2条答案

按热度按时间

fbcarpbf1#

fetch是一个承诺，因此您需要等待fetch并返回blob响应

app.get("/media/bigfootjinx", async (req, res, next) => {
    let file = Math.floor(Math.random()*catarray.length)
        let fileurl = catarray[file]
        let response = await fetch(fileurl)
        let fileimg = await response.blob()
    let img = await blobToBase64(fileimg);
    res.writeHead(200, {
        'Content-Type': 'image/png',
        'Content-Length': img.length
    });
    res.end(img); 
});

从blob到base64的转换函数：

function blobToBase64(blob) {
  return new Promise((resolve, _) => {
    const reader = new FileReader();
    reader.onloadend = () => resolve(reader.result);
    reader.readAsDataURL(blob);
  });
}

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xqkwcwgp2#

以下代码行导致该错误：

let img = Buffer.from(fileimg, 'base64');
let fileimg = fetch(fileurl)

fetch()函数返回一个Promise<Buffer>，你只需 * 等待 * 获取结果，你可以这样做：

let fileimg = await fetch(fileurl)
let img = Buffer.from(fileimg, 'base64');

**注意：**get端点的回调函数必须是异步的：

app.get("/media/bigfootjinx", async (req, res, next) => {

赞(0）回复(0）举报 2023-02-03

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NodeJS 在自定义API中返回随机图像时出现问题

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