How to use Multer middleware to upload array of images - node.js

Question

Im trying to use Multer to upload an array of images. At the client side i have a FormData called pictures.
pictures array, from react-native-image-picker:
const [pictures, setPictures] = useState([]);
const imagePickerCallBack = data => {
const picturesData = [...pictures];
const index = picturesData.length;
const image = {
image: data.uri,
fileName: data.fileName,
type: data.type,
index: index,
};
picturesData.push(image);
setPictures(picturesData);
setLoad(false);
};
Step 1 - Create formData with all images:
const data = new FormData();
pictures.forEach(pic => {
data.append('pictures', {
fileName: pic.fileName,
uri: pic.image,
type: pic.type,
});
});
const headers = {
'Content-Type': 'multipart/form-data',
'x-access-token': token,
};
const diaryUpdatePost = await post(`diary/uploadPictures/${diary}`, body, {
headers,
});
Step 2 - Get the request at server side. Im setting up multer and routers:
const router = express.Router();
const multer = require('multer');
const storage = multer.diskStorage({
destination(req, file, cb) {
cb(null, 'uploads/');
},
filename(req, file, cb) {
cb(null, `${file.fieldname}-${Date.now()}`);
},
});
const upload = multer({ storage, limits: { fieldSize: 25 * 1024 * 1024 } });
// Multer with the same FormData (client)
router.post('/uploadPictures/:name', upload.array('pictures'), diaryController.uploadDiaryPictures);
And finally my diaryController, where i need to get all files:
exports.uploadDiaryPictures = async (req, res) => {
// Logging []. I cant access files from here
console.log(`files ${req.files}...`);
};
I already tried to use express-fileupload, but req.files return undefined. Some ideia to help? Thx.

Answer 1

You need to give a count of files you expect to upload:
upload.array('pictures', <number_of_pictures>)
Or if it is allowed to be any number:
upload.any('pictures')
You should also add the file itself to your form data
data.append('pictures', {
name: pic.fileName,
file: pic.image,
type: pic.type,
});

Answer 2

None of the answers here helped. The solution for me was to iteratively append EACH file object from the files array to the same field name given in Multer, instead of appending the files array itself to the field name given in Multer.
So from this:
export const addFiles= createAsyncThunk(
"addFiles",
async (payload: any, thunkApi) => {
const formData = new FormData();
// Here was the problem -- I was appending the array itself
// to the "files" field
formData.append("files", payload.files);
formData.append("data", JSON.stringify(payload?.data || {}));
const response = await axios.post('/user/products/files', formData);
if(response){
return response;
}
return thunkApi.rejectWithValue("");
}
);
I did this:
export const addFiles= createAsyncThunk(
"addFiles",
async (payload: any, thunkApi) => {
const formData = new FormData();
// The following loop was the solution
for (const file of payload.files) {
formData.append("files", file);
}
formData.append("data", JSON.stringify(payload?.data || {}));
const response = await axios.post('/user/products/files', formData);
if(response){
return response;
}
return thunkApi.rejectWithValue("");
}
);
This was my Multer configuration:
multer({ dest: "/uploads" }).array("files")
The files posted to my endpoint were then available to me at:
req.files
PS: Although the accepted answer kind of did that, he did not mention that you cannot append the entire array at once, which was the main problem for me.