Read/write binary data to MongoDB in Node.js - node.js

Question

I've been able to successfully write binary data (an image) to MongoDB in Node.js. However I can't find clear documentation on how to read it back.
Here's how I'm writing the image to MongoDB:
var imageFile = req.files.myFile;
var imageData = fs.readFileSync(imageFile.path);
var imageBson = {};
imageBson.image = new db.bson_serializer.Binary(imageData);
imageBson.imageType = imageFile.type;
db.collection('images').insert(imageBson, {safe: true},function(err, data) {
I'd appreciate any pointers on reading the image from Mongo using Node. I'm assuming there's a function like "db.bson_deserializer...". Thanks!

Answer 1

Found the answer:
var imageFile = req.files.myFile;
fs.exists(imageFile.path, function(exists) {
if(exists)
{
console.log("File uploaded: " + util.inspect(imageFile));
fs.readFile(imageFile.path, function(err, imageData) {
if (err) {
res.end("Error reading your file on the server!");
}else{
//when saving an object with an image's byte array
var imageBson = {};
//var imageData = fs.readFileSync(imageFile.path);
imageBson.image = new req.mongo.Binary(imageData);
imageBson.imageType = imageFile.mimetype;
console.log("imageBson: " + util.inspect(imageBson));
req.imagesCollection.insert(imageBson, {safe: true},function(err, bsonData) {
if (err) {
res.end({ msg:'Error saving your file to the database!' });
}else{
fs.unlink(imageFile.path); // Deletes the file from the local disk
var imageBson = bsonData[0];
var imageId = imageBson._id;
res.redirect('images/' + imageId);
}
});
}
});
} else {
res.end("Oddly your file was uploaded but doesn't seem to exist!\n" + util.inspect(imageFile));
}
});

Answer 2

The MongoDB part isn't complicated. Once a Buffer is in the model, just let the db save it. MongoDB converts that into BinData. 80% of this code is just getting an image into and out of a PNG file.
People say don't store images in MongoDB, but icons/thumbs are tiny. Having said that, it might be a good idea to have an icons collection and only store them once using a hash of the image data as the _id.
model class example
class MyModel {
_icon: Buffer
get icon(): Buffer {
return this._icon
}
set icon(value: Buffer) {
this._icon = value
}
}
image helper
static async loadImage(url: string) {
var files = require('../lib/files')
var buffer = await files.urlContents(url, true)
return buffer
}
static async saveImage(image: Buffer, path: string) {
var files = require('../lib/files')
files.write(path, image.buffer)
return path
}
files helper
function urlResponse(url, binary) {
var request = require("request")
if (binary)
request = request.defaults({ encoding: null })
return new Promise(function (resolve, reject) {
request(url, function (error, res, body) {
if (error || res.statusCode !== 200 || body.includes('Incomplete response received from application'))
resolve({ statusCode: res?.statusCode !== 200 ? (res?.statusCode || 500) : 500 });
else
resolve(res);
});
});
}
async function urlContents(url, binary) {
var res = await urlResponse(url, binary)
if (binary)
return Buffer.from(res.body)
else
return res.body
}
function write(fileName, contents) {
fs.writeFileSync(fileName, contents)
}
mongodb helper
// ...saving
myModel.icon = loadImage('http://some.site.com/image.png')
collection.insertOne(myModel)
// ..getting
myModel = collection.findOne(query) // now myModel contains icon
saveImage(myModel.icon, '/home/toddmo/pictures/wow.png')