How to restrict file upload, if it is not valid file format in loopback? - file-upload

Question

I have added meta data by referring How to store files with meta data in LoopBack?
Now I have to check if the filetype is in csv, before uploading it to the server.
Right now, I delete the uploaded file if it is not valid. Is there a better way to solve this?
let filePath;
File.app.models.container.upload(ctx.req, ctx.result, options, function(err, fileObj) {
if (err) {
callback(err);
}
let fileInfo = fileObj.files.file[0];
filePath = path.join("server/storage", fileInfo.container, fileInfo.name);
if (fileInfo.type === "text/csv") {
File.create({
name: fileInfo.name,
type: fileInfo.type,
container: fileInfo.container,
url: path.join(CONTAINERS_URL, fileInfo.container, "/download/",
fileInfo.name)
}, function(err, obj) {
if (err) {
callback(err);
}
callback(null, filePath);
});
} else {
fs.unlinkSync(filePath); //delete if it is not csv
let error = new Error();
error.message = "Please upload only csv file";
error.name = "InvalidFile";
callback(error);
}
});

Answer 1

Here is what I've done,
in middleware.json
"parse": {
"body-parser#json": {},
"body-parser#urlencoded": {"params": { "extended": true }}
},
in server/server.js
var multer = require('multer');
var boot = require('loopback-boot');
var app = module.exports = loopback();
app.use(bodyParser.json()); // for parsing application/json
app.use(bodyParser.urlencoded({ extended: true })); // for parsing application/x-www-form-urlencoded
app.use(multer()); // for parsing multipart/form-data
and remote method as ,
File.remoteMethod(
'upload', {
description: 'Uploads a file with metadata',
accepts: {arg: 'ctx', type: 'object', http: function(ctx) {
console.log(ctx.req.files);
return ctx;
}
},
returns: {arg: 'fileObject', type: 'object', root: true},
http: {verb: 'post'}
}
);
Now ctx can give the mime type..
Update 1:
There is another easier option,
You could define the restriction in datasources.local.js as below, I tested with a filesystem provider
module.exports = {
container: {
root: "./upload",
acl: 'public-read',
allowedContentTypes: ['image/jpg', 'image/jpeg', 'image/png'],
maxFileSize: 10 * 1024 * 1024
}
}