GridFS + NodeJS Retrieve image from mongoDB

Question

I have the following JSON from mongoDB with images but I don't know how to display it:

fs.chunks:

{
        "_id" : ObjectId("542e684a8a1cec178a172673"),
        "n" : 1,
        "data" : BinData(0,"2N6DSSfbCN/LLacNDYrJUQDEZgimMUwFpQGoJP0RU19Bi4PM82DjrUnKhE/P9v7P8ZveD1oDpFBM0iml9NE3WQmAvYFoG+nhD73Jm4N9b4LpylaAN5Ef+gVdgGSTAfSUwOikXoVick5pSQCkRmTCU5NT9VVfjHdAx74/ZhFRj+TIRjzlAhzkACBElzgMwGCo7tX+FYrpQLJ5KRmXiwFFwsNtHHzXiK1eu+CG1FumhGpA/qdG8CdDgD1xUHEcerMGO/eLGR9ML7ni/VjXxWzqp2j5DG2/WuKNv7xd3Kz/vr0MctJhuaBIl35YrKhdLnzqDa0uDa6bm4jz+eNyAI2hQbayGo4kVPFe8W7wFpY7qfBvnB9kbocxfZSdADDUNwYaydpT8lIcKEN9XfQJOYZvHp0El"),
        "files_id" : ObjectId("542e684a8a1cec178a172671")
}

fs.files:

{
        "_id" : ObjectId("542e65378axdeckhb0"),
        "uploadDate" : ISODate("2012-11-01"),
        "length" : 15673,
        "chunkSize" : 33222,
        "md5" : "f66e6654854a28e3672cfhds334d223b55a1"
}

Need to turn "data" into a real image to display.

I am using nodeJS and I can't find good tutorials to retrieve images from mongoDB with GridFS.

Thanks for your help!

score 1 · Answer 1 · answered Jul 16 '19 at 21:05

Sorry this answer is super late, but I'm surprised no one has answered it yet. Anyway, the following code will download the file, presuming you are running Express. You will need to wrap the gfs.findOne() function into an API call.

const Grid = require('gridfs-stream');
const mime = require('mime');
const mongoose = require('mongoose');

// connect to the db, fill in the username/password/host/port/dbName.
// Ideally the connection is set up before the main part of the app runs.
const path = 'mongodb://username:password@host:port/dbName';
const dbConnection = mongoose.createConnection(path);

const gfs = new Grid(dbConnection.db);

// then once you get the id of the file you want:
gfs.findOne({
    _id: id
}, (err, file) => {
    if (err) {
        // report the error
    } else {
        // detect the content type and set the appropriate response headers.
        let mimeType = file.contentType;
        if (!mimeType) {
            mimeType = mime.lookup(file.filename);
        }
        res.set({
            'Content-Type': mimeType,
            'Content-Disposition': 'attachment; filename=' + file.filename
        });

        const readStream = gfs.createReadStream({
            _id: id
        });
        readStream.on('error', err => {
            // report stream error
        });
        // the response will be the file itself.
        readStream.pipe(res);
    }
});

I am getting an error: UnhandledPromiseRejectionWarning: TypeError: cursor.nextObject is not a function — Sheece Gardazi, Jun 07 '20 at 04:32
@SheeceGardazi Can you link to your code somewhere? If not, I would suggest posting your problem as a separate question. — MForMarlon, Jun 08 '20 at 06:49
Adding this: eval(`Grid.prototype.findOne = ${Grid.prototype.findOne.toString().replace('nextObject', 'next')}`); Solved my issue, I added the solution here https://stackoverflow.com/a/62241037/4935275 — Sheece Gardazi, Jun 08 '20 at 08:57
I will probably update my answer in the next couple of weeks, now that MongoDB has their official [GridStore API](https://docs.mongodb.com/manual/core/gridfs/), and the owner of gridfs-stream has stopped developing. — MForMarlon, Jun 09 '20 at 16:25

GridFS + NodeJS Retrieve image from mongoDB

1 Answers1