I've read through a dozen posts on how to convert between ArrayBuffer to Blob or to Uint8Array etc. before sending the data to the client side... but I can't seem to be able to get it to work at all. When I do get the data through, I was not able to reconstruct them back as a Blob before outputting it to a file..
const Blob = require('cross-blob');
const randomBytes = require('randombytes');
const buffer = randomBytes(1024); // Supposed to give me Buffer
The followings were the stuff I tried...
data = buffer;
^ gives me <Buffer 11 22 33 ...>
data = Uint8Array.from(buffer);
^ gives me an array of integer, this looked the most promising? but when arrived to the client side, it became an object with indexes and byte value...
data = Uint8Array.from(buffer).buffer;
^ gives ArrayBuffer { byteLength: 1024}, when inspect it shows size: 2 and type: 'text/plain'...
data = new Blob(buffer, { type: 'application/octet-stream' });
data = new Blob([new Uint8Array(buffer, buffer.byteOffset, buffer.length)], { type: 'application/octet-stream' });
data = new Blob([Uint8Array.from(buffer)], { type: 'application/octet-stream' });
^ all these, when arrived to the client side also with size: 2 and type: 'text/plain'...
On the server side, I am running Express:
router.get('/test/*', function(req, res, next) {
...
let data = myFunctionThatGeneratesData();
res.send(data);
});
On the client side, I'm requesting it like this (Angular/TypeScript):
this.http.get('/test/random-bytes-array', {
responseType: 'blob' // also tried 'arraybuffer'
}).subscribe(data => {
debugger;
console.log(data);
});
I must be doing something wrong... I am trying to send multiple chunk of binary data over, either as an ArrayBuffer, Uint8Array or Blob (whatever works) and when arriving at the other end, combine them back into a Blob.
In Node.js, crypto.randomBytes returns a Buffer. This is the correct type to use for sending raw data to the client.
When using Express, it is important to set the correct content-type of the response using res.type(). However, when sending a Buffer, if the content-type header is not set in any other middleware, then express will use application/octet-stream by default.
When the parameter is a Buffer object, the method sets the Content-Type response header field to "application/octet-stream", unless previously defined.
router.get('/test/*', function(req, res, next) {
...
let data = myFunctionThatGeneratesData();
res.type('application/octet-stream').send(data);
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ might not be necessary
});
And lastly in Angular, using the responseType: 'blob' is correct:
this.http.get('/test/random-bytes-array', {
responseType: 'blob'
}).subscribe(data => {
console.log(data);
});