如何在课堂上制作快速中间件?

Question

我目前使用的多中间件如下

const storage = multer.diskStorage({
destination: function (req, file, cb) {
cb(null, "public");
},
filename: function (req, file, cb) {
cb(null, req.params.id + "_" + file.originalname);
},
});

export const multerUploadSingle = (req: Request, res: Response, next: NextFunction) => {
const upload = multer({ storage: storage }).single("file");
upload(req, res, (error: unknown) => {
if (error instanceof multer.MulterError) {
const message = `file upload fail: ${error.message}`;
next(new HttpException(message, HttpStatus.BadRequest));
} else if (error instanceof Error) {
const message = `file upload fail: ${error.message}`;
next(new HttpException(message, HttpStatus.InternalServerError));
} else {
// upload success
next();
}
});
}

并在路由器中使用

FileRouter.post("/upload/:id", multerUploadSingle, (req, res) => {...});

然而，我觉得我想在类中重构这个中间件，并像这样重写代码，

export class Multer {
private readonly storage: multer.StorageEngine;
constructor() {
this.storage = multer.diskStorage({
destination: function (req, file, cb) {
cb(null, "public");
},
filename: function (req, file, cb) {
cb(null, req.params.id + "_" + file.originalname);
},
});
}
uploadSingle(req: Request, res: Response, next: NextFunction) {
const upload = multer({ storage: this.storage }).single("file");

upload(req, res, (error: unknown) => {
if (error instanceof multer.MulterError) {
const message = `file upload fail: ${error.message}`;
next(new HttpException(message, HttpStatus.BadRequest));

} else if (error instanceof Error) {
const message = `file upload fail: ${error.message}`;
next(new HttpException(message, HttpStatus.InternalServerError));

} else {
// upload success
next();
}
});
}
}

const multer = new Multer();
FileRouter.post("/upload/:id", multer.uploadSingle, (req, res) => {...});

以我简短的知识，我认为这两种情况应该有相同的结果，但后一种情况下，使用类制作的中间件根本不起作用。好像是uploadsingle方法永远不会被调用，从而避免不上传文件。

我在类用法上有什么错误吗?还是仅仅表示只能使用函数定义的中间件?

Answer 1

您的代码应该遵循MVC模式。你可以这样做:

routerFile.js

const upload = require("../../configs/multer");
const postController = require("../../controllers/postController");
const multiUploadEvent = upload.fields([
{ name: "images", maxCount: 2 },
{ name: "video", maxCount: 2 }
]);
router.post("/add-event-post", multiUploadEvent, postController.addEventPost);
module.exports = router;

multer.js

const multer = require('multer');
const multerFilter = (req, file, cb) => {
console.log("Mime type :", file.mimetype.split('/')[0]);
if (file.mimetype.split('/')[0] === 'image' || file.mimetype.split('/')[0] === 'video' || file.mimetype.split('/')[0] === 'audio') {
cb(null, true);
} else {
cb(new Error('Please upload img, audio, or video file only.'), false);
}
};
const storage = multer.memoryStorage();
const upload = multer({
storage: storage,
fileFilter: multerFilter,
limits: {
fileSize: , 50 * 1024 * 1024// 50 Mb
},
});
module.exports = upload;

postController.js

const addEventPost = async (request, response) => {
try {
let { title, ..... } = request.body;
const images = request.files.images;
const video = request.files.video;

console.log(title);
console.log(images);
console.log(videos);
//upload to services likes aws and save to database
.
.
.
return response
.status(200)
.json({
message: "Event post added successfully"
});
} catch (error) {
console.log(error);
response.status(500).json({
error: "Something went wrong",
});
}

}