File Upload With Loopback

Question

I created a simple file uploading application with loopbackjs. In the application's client side I used simple HTML and Javascript code, calling a loopback api with an AJAX call:

$('#upload-input').on('change', function () {

    var files = $(this).get(0).files;

    if (files.length > 0) {
        // One or more files selected, process the file upload
        var form = new FormData();

        for (var index = 0; index < files.length; index++) {

            var file = files[index];
            form.append('Uploded Files', file, file.name);
        }

        $.ajax({
            url: 'api/fileupload/upload',
            type: 'POST',
            data: form,
            processData: false,
            contentType: false,
            success: function (data) {
                console.log('upload successful!');
            }
        });
    }

});

We are not getting files on the server side. On the server side we created a Loopback API, but how can we upload files with this API?

This is my loopback API code:

FileUpload.remoteMethod

(
        'upload', {
            http: {
                verb: 'post',
            },
            accepts:
            [
                { arg: 'ctx', type: 'object', http: { source: 'context' } },
                { arg: 'options', type: 'object', http: { source: 'query' } }

            ],
            returns: {
                arg: 'data',
                type: 'string',
                root: true
            }
        }
    );

    FileUpload.upload = function (context, options, callback) {
        //context.req.params = 'common';

    };

Answer 1

Install multer : https://github.com/expressjs/multer

npm install --save multer

In MyModel.js

var multer = require('multer');
var fs = require('fs');

module.exports = function (MyModel) {
    var uploadedFileName = '';
    var storage = multer.diskStorage({
        destination: function (req, file, cb) {
            // checking and creating uploads folder where files will be uploaded
            var dirPath = 'client/uploads/'
            if (!fs.existsSync(dirPath)) {
                var dir = fs.mkdirSync(dirPath);
            }
            cb(null, dirPath + '/');
        },
        filename: function (req, file, cb) {
            // file will be accessible in `file` variable
            var ext = file.originalname.substring(file.originalname.lastIndexOf("."));
            var fileName = Date.now() + ext;
            uploadedFileName = fileName;
            cb(null, fileName);
        }
    });


    MyModel.upload = function (req, res, cb) {
        var upload = multer({
            storage: storage
        }).array('file', 12);
        upload(req, res, function (err) {
            if (err) {
                // An error occurred when uploading
                res.json(err);
            } else {
                res.json(uploadedFileName);
            }
        });        
    };

    MyModel.remoteMethod('upload',   {
        accepts: [{
            arg: 'req',
            type: 'object',
            http: {
                source: 'req'
            }
        }, {
            arg: 'res',
            type: 'object',
            http: {
                source: 'res'
            }
        }],
        returns: {
             arg: 'result',
             type: 'string'
        }
    });
};

Frontend - I use AngularJS, so for that follow -https://github.com/nervgh/angular-file-upload

there are also other such directives to use

P.S. - As per your comment - Actually Our Problem is that , we need to upload a File from Client Side and Store this File in Database , But Before save in DB , we need to get files on Server side , if we get Files on Server side via Post API than we can easily store file in DB

Can't provide you exact solution, but using above method files will be uploaded in your /client/uploads folder, once uploaded then you have control on what to do with file and once everything is done, eventually delete it(optional)