multer not uploading multiple images node.js

Question

I have a react application trying to upload multiple files using formdata. It seems to be able to do upload.single() but not upload.array() on the backend. And I cannot figure out why.

Function handling the upload when a button is clicked

  const handleUpload = async () => {
    let data = new FormData();
    data.append("files", imageList);
    data.append("title", title);
    data.append("short_text", shortText);
    data.append("news", news);
    const response = newsUpload(data);
    console.log(response);
  };

The api function on the front-end

export const newsUpload = async (data) => {
  return await api
    .post(`api/news/upload`, data)
    .then((data) => {
      return "DONE!";
    })
    .catch((err) => {
      console.log(err.response.data);
    });
};

Back-end: I instantiate the multer instance in the server.js file which is the run file.

var storage = multer.diskStorage({
  destination: function (req, file, cb) {
    cb(null, "uploads/");
  },
  filename: function (req, file, cb) {
    cb(null, req.userId + Date.now() + ".jpeg");
  },
});
const upload = multer({ storage: storage });

and I then send the upload function into the router:

require("./app/routes/news.routes")(app, upload);

news.routes.js defines the route for api/news/upload with the upload.array() being sent through:

app.post(
    "/api/news/upload",
    [authJwt.verifyToken, authJwt.isAdmin],
    upload.array("files",5),
    controller.upload
  );

If I change the upload.array("files",5) to upload.single("file") and change the front-end accordingly, it works by uploading one file.

I have no idea why upload.array() doesnt work.

Sweet · Accepted Answer · 2022-04-06 12:44:50Z

2

The problem was that data.append("files", imageList); was essentially appending an array to an array, so the file array sent to the api was [[Files]], instead of a required [Files].

Changing it to

for (let i = 0; i < imageList.length; i++) {
  data.append("files", imageList[i]);
}

Fixed the problem.

answered Apr 6, 2022 at 12:44

Sweet

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