How to make a validation of size image and type of image like .jpg and .png with multer?

Question

I am using the multer to receive the files from FrontEnd and after I want to do a validation in this image to know if it's less than 1MB, because if not, I will return that image is big and must be less than 1MB and I want to make too a validation to accept only images type of .jpg, .jpeg and .png.

const multer = require("multer");
const path = require("path");
const shortid = require("shortid");

const diskStorage = multer.diskStorage({    
    destination: (req, file, cb) =>{
        cb(null, 'imagens')
    },

    filename: (req, file, cb) =>{
        cb(null, Date.now() + shortid.generate() + path.extname(file.originalname)); //o nome de como eu quero salvar o nome de cada imagem, tem que ser unico
    }
});

module.exports = diskStorage;

After receive the datas from FrontEnd.

const diskStorage = require("../classes/uploadImagem");
const upload = multer({ storage: diskStorage }); //configurando o multer para dizer aonde vai salvar as imagens e como vai ficar o nome do arquivo

router.post("/criarconta", upload.fields([{ name: "photos" }]), async(req, res) =>{       
    var files = [];

    if (req.files) {
        files = req.files.photos;    
        //console.log(files);    
    }

let photos = []; //criei array de fotos com image path

        if (files && files.length > 0) { //para saber se foram enviados as fotos pela requisição
            files.forEach((photo, i) => {
                photos[i] = photo.path; //salvando todas as fotos
            });
        }

        if (files.length > 1) {
            return res.status(400).json({ erro: "Não é permitido o upload de mais de 1 imagem!" });
        }

return res.status(200).json({ erro: null, foto: photos });

});

Answer 1

Add the following verifications in the route handler:

const multer = require("multer");
const path = require("path");
const shortid = require("shortid");

const diskStorage = multer.diskStorage({    
  destination: (req, file, cb) => {
    cb(null, 'imagens');
  },
  filename: (req, file, cb) => {
    cb(null, Date.now() + shortid.generate() + path.extname(file.originalname));
  }
});

const upload = multer({
  storage: diskStorage,
  limits: {
    fileSize: 1 * 1024 * 1024 // 1Mb
  },
  fileFilter: (req, file, cb) => {
    const acceptedExtensionsList = [".jpg", ".jpeg", ".png"];
    const extname = path.extname(file.originalname).toLowerCase();
    if (acceptedExtensionsList.includes(extname)) {
      cb(null, true); // Accept the file
    } else {
      cb(new Error("Invalid file extension"));
    }
  }
});

// Error handler middleware for Multer errors
const errorHandler = (err, req, res, next) => {
  if (err instanceof multer.MulterError) {
    // Multer error occurred (e.g., file size limit exceeded)
    return res.status(400).json({ error: "File upload error: " + err.message });
  } else if (err.code === "LIMIT_FILE_SIZE") {
    // File size limit exceeded
    return res.status(400).json({ error: "File size limit exceeded. Max file size is 1MB." });
  } else {
    // Other errors
    return res.status(500).json({ error: "Internal server error" });
  }
};

router.post("/criarconta", upload.fields([{ name: "photos" }]), async (req, res) => {
  var files = [];

  if (req.files) {
    files = req.files.photos;    
  }

  if (files.length > 1) {
    return res.status(400).json({ erro: "Não é permitido o upload de mais de 1 imagem!" });
  }

  let photos = [];

  if (files && files.length > 0) {
    files.forEach((photo, i) => {
      photos[i] = photo.path;
    });
  }

  return res.status(200).json({ erro: null, foto: photos });
});