npm azure-storage download file as base64 - node.js

Question

I am using this package to download the file from azure to local node server. But I do not want to save the file in local server and then read it to convert to base64, I want to directly convert it to base64. How can I achieve this?
this.blobService.getBlobToStream('pictures', path, fs.createWriteStream(`./src/temp/${filename}.jpeg`), function(error, result, response) {
if (!error) {
resolve({ message: `Items in container pictures:`, data: result});
} else {
reject(error);
}
});

Answer 1

Built-in Node only supports ecnode Buffer type to base64, since you don't want to download blob to local server, you have to use external module to encode stream.
npm install base64-stream then use code below.
var base64 = require('base64-stream');
...
this.blobService.createReadStream(container, path).pipe(base64.encode()).pipe(res);
Notice that in your later question, you specify Content-Type using
res.header('Content-Type', properties['contentType']);
Content-Type setting should be omitted. In my test, if set Content-Type successfully, the image will be downloaded as attachment instead of being displayed as inline content. Your code succeeds because it actually sets Content-Type to undefined.
Properties you use is a BlobResult(Json format)with blob info
BlobResult {
container: xxx,
...
contentSettings:
{ contentType: 'image/jpg',
contentMD5: 'uNkt2WJ75X13TjQbfY7qkA==' },
...
}
So contentType should be used in this format properties.contentSettings.contentType