Question

19

Convert Base64 image to raw binary with Node.js

rated 0 times [ 20] [ 1] / answers: 1 / hits: 20306 / 11 Years ago, wed, september 25, 2013, 12:00:00

I have found posts that are close to what I'm looking for, but I have not been able to successfully implement what I want. Here is the general flow:

Submit photo with rest of venue data, as base64 data

Strip data prefix if it exists, so I have just the image base64 data

var base64data = venue.image.replace(/^data:image/png;base64,|^data:image/jpeg;base64,|^data:image/jpg;base64,|^data:image/bmp;base64,/, '');

Store Base64 data in GridFS via MongoDB (I'm using gridfstore)

Then, I'd like to retrieve the image upon request as a raw image file via a URL.

// generic images route

server.get(version+'/images/:id', function(req, res) {

  gridfstore.read( req.params.id, function(error,data) {

    res.writeHead(200, {

      'Content-Type': 'image/jpeg',

      'Content-Length': data.buffer.length

    });



    res.end(data.buffer);

  });

});

Basically, this method returns the Base64 bytes stored in GridFS. I have tried other methods but they don't return the raw image.

I'd like to pull up the image using URLs like this:

http://[localhost]/1/images/11dbcef0-257b-11e3-97d7-cbbea10abbcb

Here is a screenshot of the browser trace:
browser

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janeth

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2 Years ago

answered 11 Years ago kaleyv · Accepted Answer

You can take the string from MongoDB, create a new buffer instance, and specify an encoding when doing so. The resultant buffer will be in binary data.

var b64str = /* whatever you fetched from the database */;

var buf = Buffer.from(b64str, 'base64');

So in your implementation:

server.get(version+'/images/:id', function(req, res) {

  gridfstore.read(req.params.id, function(err, data) {

    var img = Buffer.from(data.buffer, 'base64');



    res.writeHead(200, {

      'Content-Type': 'image/jpeg',

      'Content-Length': img.length

    });

    res.end(img); 



  });

});