Utilizing [Multer][1] as middleware for handling multipart form data, I am taking advantage of the configuration options it provides through diskStorage. This feature allows for error checking and control over file uploads within Multer.
The structure of my Express route is as follows:
expressRouter.post(['/create'],
MulterUpload.single("FileToUpload"), // If an error occurs here, Express will return it to the user
async function(req, res) {
// Process form text fields in req.body here
});
MulterUpload.single() directs the file input field named "FileToUpload" for processing:
const MulterUpload = multer({
storage: MulterStorage
)}
const MulterStorage = multer.diskStorage({
destination: async function (req, file, cb) {
try {
if ("postID" in req.body && req.body.postID != null && req.body.postID.toString().length) {
const Result = await api.verifyPost(req.body.postID)
if (Result[0].postverified == false) {
const Err = new Error("That is not your post!");
Err.code = "ILLEGAL_OPERATION";
Err.status = 403;
throw(Err); // Unauthorized upload attempt
} else {
cb(null, '/tmp/my-uploads') // Allowed upload
}
}
} catch (err) {
// How can I send this error back to Express for returning it to the user? The error remains unresolved due to the use of async/await.
}
}
,
filename: function (req, file, cb) {
cb(null, file.fieldname + '-' + Date.now())
}
})
I'm faced with the challenge of figuring out how to relay the error from MulterStorage back to Express, which would then present it to the browser/user as an error message.
[1]: https://www.npmjs.com/package/multer