How to save base64 encoded file in LoopBack within a hook - node.js

Question

I'm trying to find a way to save a file in a loopback application that was send as base64 encoded string.
So I have a model with all possible field and also a base64 encoded image, “receipt”.
{
...modelData,
"receipt": "datadata:image/jpeg;base64,whatever=="
}
So... what I'm thinking of is this
Model.beforeRemote('create', function(ctx, model, next) {
const file = ctx.args.data.receipt;
app.models.Attachment.upload(...)
// and replace base64 with returned filename
})
But I don't clearly understand how and what should I pass to that upload method. Or maybe it has to be some different approach.
Thanks!

Answer 1

This isn't really a remote hook but rather a remote method, yet I believe you can adapt the code to your own needs.
We basically create a remote method called "upload" for Documents model and it takes care of uploading it to a predefined container name.
const CONTAINERS_URL = '/api/container/';
const fs = require('fs');
const path = require('path');
const encodedFileContainer = 'files';
module.exports = function(Document) {
Document.upload = function(encodedFile, fileName, cb) {
let uploadStream = Document.app.models.container.uploadStream(
encodedFileContainer,
fileName
);
uploadStream.end(encodedFile, 'base64', async err => {
if (err) return cb(err);
let newRecord = await Document.create(
{
fileName,
url: CONTAINERS_URL + encodedFileContainer + '/download/' + fileName,
container: encodedFileContainer
},
function(err, obj) {
if (err !== null) {
cb(err);
} else {
cb(null, obj);
}
}
);
});
};
Document.remoteMethod('upload', {
description: 'Uploads a file',
accepts: [
{
arg: 'endcodedFile',
type: 'string',
required: true,
description: 'base64 encoded file',
http: {source: 'form'}
},
{
arg: 'fileName',
type: 'string',
required: true,
description: 'file name',
http: {source: 'form'}
}
],
returns: {
arg: 'fileObject',
type: 'object',
root: true
},
http: {verb: 'post'}
});