javascript - How do I transfer base64 data into a readable image stream without saving locally

Question

I'm working with the Microsoft Bot Framework (hosting on Azure) using Node.js, and saving files locally isn't an option. I have image data in base64 format, and I need to transfer that data into a readable stream of an image file that I can pump into Azure using their Blob Storage API (which takes a stream).

            var base64ImageData; //my base64 image

            //Create myStream here

            //Then send to Azure
            blobService.createBlockBlobFromStream('mycontainer', 
            nameForBlob, myStream, fileSize, 
            function (error, result, response){ 
                if(!error)
                    console.log(response);
                else
                    console.log(error)
            });

Any help would be appreciated. I can't figure out how to decode the base64 and make a stream out of it without saving a jpg onto my disk.

Answer 1

Please try something like this:

var azureStorage = require('azure-storage');
var streamifier = require('streamifier');

var base64String = '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';
var blobService = azureStorage.createBlobService('account-name', 
    'account-key');
var buffer = Buffer.from(base64String, 'base64');
var stream = streamifier.createReadStream(buffer);
blobService.createBlockBlobFromStream('container-name', 'checked.png', stream, buffer.byteLength, function(error, response) {
        if (error) {
            console.log('Error!');
            console.log(error);
        } else {
            console.log('Blob uploaded successfully!');
            console.log(response);
        }
    });

I had to install streamifier node package to convert buffer to stream.