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Multer is a node.js middleware for handling multipart/form-data, which is primarily used for uploading files. It is written on top of busboy for maximum efficiency.
File Uploads
This feature allows you to upload files to your server. The code sample demonstrates how to handle a single file upload with Multer.
const multer = require('multer');
const upload = multer({ dest: 'uploads/' });
app.post('/upload', upload.single('file'), function (req, res) {
// req.file is the `file` file
res.send('File uploaded!');
});
Multiple Files Upload
Multer also supports uploading multiple files at once. The code sample shows how to handle multiple file uploads, limiting to 12 files in this case.
const multer = require('multer');
const upload = multer({ dest: 'uploads/' });
app.post('/upload', upload.array('files', 12), function (req, res) {
// req.files is array of `files` files
res.send('Multiple files uploaded!');
});
Disk Storage
Multer allows you to customize the storage of files. This code sample demonstrates how to use disk storage to control the storage location and file naming.
const multer = require('multer');
const storage = multer.diskStorage({
destination: function (req, file, cb) {
cb(null, 'uploads/')
},
filename: function (req, file, cb) {
cb(null, file.fieldname + '-' + Date.now())
}
});
const upload = multer({ storage: storage });
Memory Storage
For temporary storage or when you want to process the file without saving it to disk, you can use memory storage. The code sample shows how to store a file in memory.
const multer = require('multer');
const upload = multer({ storage: multer.memoryStorage() });
app.post('/upload', upload.single('file'), function (req, res) {
// req.file is the `file` file stored in memory
res.send('File uploaded and stored in memory!');
});
File Filtering
Multer provides a way to filter out files based on conditions you set. This code sample demonstrates file filtering to only allow JPEG images.
const multer = require('multer');
const upload = multer({
fileFilter: function (req, file, cb) {
if (file.mimetype !== 'image/jpeg') {
return cb(new Error('Only JPEG files are allowed!'), false);
}
cb(null, true);
}
});
Formidable is an alternative to Multer for parsing form data, especially file uploads. It is less middleware-oriented and more flexible in terms of handling various form parsing tasks.
Busboy is a low-level Node.js module for parsing incoming HTML form data. Multer is built on top of Busboy, but provides a more convenient middleware API for integrating with Express.js applications.
Multiparty is another module for handling multipart/form-data requests, which is the type of requests that file uploads usually come in. It is similar to Multer but has a different API and is used in a slightly different way.
Multer is a Connect middleware for handling multipart/form-data
FAQs
Middleware for handling `multipart/form-data`.
The npm package multer receives a total of 4,139,357 weekly downloads. As such, multer popularity was classified as popular.
We found that multer demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 3 open source maintainers collaborating on the project.
Did you know?
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