typescript - Multer 处理错误， typescript 类型有问题

Question

我有以下代码:

import multer from "multer";
const upload = multer().single('file');
router.post('/add', async (req, res) => {
    upload(req, res, async (err: any) => {
        if (err) {
            res.status(500).send(err.toString())
        }
        else {
            res.status(200).send(await addMedia(req.file.filename))
        }
    })
});

我正在尝试确定类型，所以我想用适当的错误类型替换 any。当我尝试用 MulterError 替换它时，出现以下错误:

Argument of type '(err: MulterError) => Promise' is not assignable to parameter of type 'NextFunction'. Types of parameters 'err' and 'deferToNext' are incompatible. Type 'string' is not assignable to type 'MulterError'.

由于 .toString()，

unknown 不起作用。 string 确实有效，但它绝对不是正确的类型，因为记录它显示我有一个 MulterError。

我也不完全理解 upload 函数的第三个参数是什么 - 所以这可能是我的问题。

Answer 1

这是我处理错误的方式

const storage: multer.StorageEngine = multer.diskStorage({
    destination: (_req, _file, callback) => {
        const path = `./uploads/`;
        // creates folder if not exist
        fs.mkdirSync(path, { recursive: true });
        callback(null, path);
    },
    filename: (_req, file, callback) => {
        callback(null, new Date().toISOString() + file.originalname);
    }
});

const fileLimit = {
    fileSize: 1024 * 1024 * 10 // limits the file size to 10MB
};
const fileFilter = (
    _req: Request,
    file: Express.Multer.File,
    callback: FileFilterCallback
) => {
    // return error if the file type is not image
    if (!file || file.mimetype.split('/')[0] != 'image') {
        return callback(new Error('Only images allowed'));
    }
    callback(null, true);
};

const upload: multer.Multer = multer({
    storage: storage,
    limits: fileLimit,
    fileFilter: fileFilter
});

const galleryUpload = upload.single('galleryImage');
// Upload gallery image
router.post('/', async (req: Request, res: Response) => {
    galleryUpload(req, res, (err: unknown) => {
        if (err instanceof multer.MulterError) {
            // A Multer error occurred when uploading.
            return res.status(400).send({ message: err.message });
        } else if (err instanceof Error) {
            // An unknown error occurred when uploading.
            return res.status(400).send({ message: err.message });
        }
        return res.status(200).send({ message: 'Image uploaded successfully' });
    });
});