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NodeJs Microsoft Azure Storage SDK Download File to Stream

I just started working with the Microsoft Azure Storage SDK for NodeJS (https://github.com/Azure/azure-storage-node) and already successfully uploaded my first pdf files to the cloud storage.
However, now I started looking at the documentation, in order to download my files as a node_buffer (so I dont have to use fs.createWriteStream), however the documentation is not giving any examples of how this works. The only thing they are writing is "There are also several ways to download files. For example, getFileToStream downloads the file to a stream:", but then they only show one example, which is using the fs.createWriteStream, which I dont want to use.
I was also not able to find anything on Google that really helped me, so I was wondering if anybody has experience with doing this and could share a code sample with me?

The getFileToStream function need a writable stream as param. If you want all the data wrote to a Buffer instead of a file, you just need to create a custom writable stream.
const { Writable } = require('stream');
let bufferArray = [];
const myWriteStream = new Writable({
write(chunk, encoding, callback) {
bufferArray.push(...chunk)
callback();
}
});
myWriteStream.on('finish', function () {
// all the data is stored inside this dataBuffer
let dataBuffer = Buffer.from(bufferArray);
})
then pass myWriteStream to getFileToStream function
fileService.getFileToStream('taskshare', 'taskdirectory', 'taskfile', myWriteStream, function(error, result, response) {
if (!error) {
// file retrieved
}
});

Save json object as a text file

I am using an API for a Twitch.tv streaming bot called DeepBot.
Here is the link to it on github https://github.com/DeepBot-API/client-websocket
My goal is to create a text document listing all the information pulled from the bot using the command api|get_users|. The bot's response is always a json object. How can I take the json object from the bot and save it as a text file?
Edit: My code
var WebSocket = require('ws');
var ws = new WebSocket('ws://Ip and Port/');
ws.on('open', function () {
console.log('sending API registration');
ws.send('api|register|SECRET');
});
ws.on('close', function close() {
console.log('disconnected');
});
ws.on('message', function (message) {
console.log('Received: ' + message);
});
ws.on('open', function () {
ws.send('api|get_users|');
});

Well that depends on how your setup is? You posted this under javascript. So I guess you are either:
using a browser, to make the websocket connection, in with case there is no direct way to save a file on the client. But in HTML5 you can store key,value pairs with local storage.
using node js (server side javascript) in witch case the code is as below:
some other setup, that I can't guess. in witch case you might tell a little more about it?
In browser with HTML5 capabilities:
// where msg is an object returned from the API
localStorage.setItem('Some key', JSON.stringify(msg));
In Node JS
var fs = require("fs"); // Has to be installed first with “npm install fs”
// where msg is an object returned from the API
fs.writeFile("some-file.json", JSON.stringify(msg), function (err) {
if (err) throw err;
});
Edit: OK, Thanks for clearing it up.
I believe Blag's solution is the way to go.
Good luck with your project!

If it's for a client side JS save :
Create a file in memory for user to download, not through server
and
Convert JS object to JSON string
Is what you need. ( I don't test it, but it'll look like this : )
var j = {"name":"binchen"};
var s = JSON.stringify(j);
window.location = 'data:text/plain;charset=utf-8,'+encodeURIComponent(s);

Getting variables From a config file to the browser

I have a rather complex setup which requires the web browser local storage has the computer's name populated in order for the application to work properly. In order to do this I read from a configuration file:
kiosk-name: Mort
I read the config file when I start my node.js web server:
var filesys = require('fs');
var os = require('os');
filesys.readFile(project_path + '/kiosk.cfg', 'utf8', function(err, data) {
var kioskname;
if (err) {
//console.log(err);
kioskname = os.hostname();
} else {
var configArray = data.split(':');
if('' != configArray[1]) {
kioskname = configArray[1];
} else {
kioskname = os.hostname();
}
}
});
All of this works as designed, using the computer's os.hostname() as a default when the config file is not populated.
The client side features a base page (index.html) which loads a default page (default.html) into an iframe. Based on a websocket messaging system the default page gets replaced by another page from a remote IP. In an older version of the system (prior to implementing a config file) we were able to set the local storage element with the following code:
var win = document.getElementsByTagName('iframe')[0].contentWindow;
win.postMessage(JSON.stringify({key: 'kiosk-name', data: kioskName}), "*");
We identify the iframe when the websocket message is received and then send a post message containing a JSON string to set the local storage element. In this case kioskName is a variable containing a hard-coded value.
The Problem
Now that we wish to read values from a config file we need a way to pass kioskname out to the client-side JavaScript so we can set the local storage element in the iframe.
I attempted putting the file reading function in an export wrapper:
(function(exports){
// file reading code here
return kioskname;
})(typeof exports === 'undefined' ? this['kioskname']={} : exports);
I got an error:
Uncaught ReferenceError: require is not defined
Placing a static value in the export function (with out the require's allows the export function to work properly, but doesn't allow me to read the config file which requires both the os and fs modules.
How do I get the value returned from the config file to a place where I can use it on the client-side to set a local storage element?

This is a creative solution which may not be suitable for every case as it involves utilizing a websocket between the Node.js web server and the client.
Websocket setup to send to client (assumes webserver at 'node_server':
var io = require('socket.io').listen(node_server); // 'attaches' socket.io to this web server
io.sockets.on('connection', function (socket) {
socket.emit('message', 'socket.io connected'); // output a connection message
// receive JSON message and send to the websocket
socket.on('message', function (data) {
var address = node_server.address();
var client = dgram.createSocket("udp4");
var message = new Buffer(data);
// out of the airlock!
client.send(message, 0, message.length, address.port, address.address, function(err, bytes) {
client.close();
});
});
});
Read the config file, then parse and send a message to the socket (done on the server-side):
filesys.readFile(project_path + '/kiosk.cfg', 'utf8', function(err, data) {
var kioskname;
if (err) {
//console.log(err);
kioskname = os.hostname();
} else {
var configArray = data.split(':');
if('' != configArray[1]) {
kioskname = configArray[1];
} else {
kioskname = os.hostname();
}
}
// create JSON string for transmission
KioskName = JSON.stringify({'config':{'kiosk-name': kioskname}});
var send_KioskName = setInterval(function(){ // could be a setTimeout for a one time send
io.sockets.emit('message', KioskName.toString()); // send config file data to browser via socket
}, 30000);
});
NOTE this can be expanded to send multiple pieces of data via JSON to the client should the need arise. A couple of small edits are all that is needed to setup a more detailed JSON object.
Receive the socket message on the client side (this code is loaded by the client), then parse. The resulting object is added to the namespace for this application, making the object available to multiple scripts when required.
CAUTION: You should only use this methodology for objects which do not interfere with objects you may create or destroy in your scripts along the way.
// make sure a string is JSON before using
function isJSON(str) {
try {
JSON.parse(str);
return true;
} catch (e) {
return false;
}
}
// set up object 'array's
var kioskname = {};
// connect a socket to listen for incoming messages from the Big Giant Head
var socket = io();
socket.on('message', function (data) {
if(isJSON(data)) {
// parse the json
var json = $.parseJSON(data);
// determine how to use this JSON object, multiple objects may be sent
if('config' == Object.keys(json)[0]) {
/*
* send config data where needed - future proofed, just add cases
* and namespaced objects where required
*/
kioskname['name'] = json.config['kiosk-name'];
}
}
});
// attach objects to namespace
window.KIOSK.kioskname = kioskname;
Now we can use the object to set local storage. In our case we post a message to the app's server and it responds with localStorage.setItem():
Post the message:
var currentFrame = document.getElementsByTagName('iframe')[0].contentWindow;
currentFrame.postMessage(JSON.stringify({key: 'user-name', data: KIOSK.kioskname.name}), "*");
By opening a socket and using the JSON string passed through the socket to populate a namespaced object we are able to use server-side information from a configuration file in our application's client.

Issue while uploading image byte array from parse cloud function

I am working on a Xamarin and creating cross platform mobile application.
I want to upload an image from mobile device to parse by using cloud function.
Below is the code in C# to upload the "Byte Array" to cloud function:
var byteArrContent = new ByteArrayContent(App.mByteArrayOfImage);
byteArrContent.Headers.ContentType = MediaTypeHeaderValue.Parse("image/png");
dictionary.Add ("ByteArray",byteArrContent);
And following is the cloud function which accepts the dictionary
function uploadImage(request,response){
var file = null;
var fileJson = {};
file = new Parse.File("profile.png", { base64: request.params.ByteArray.toString("base64") });
file.save({
success: function(savedFile){
fileJson = {"name":savedFile.getName(),"url":savedFile.getUrl()};
response.success(fileJson); },
error: function(error) {
response.error(false,request.params.ByteArray);
}
});
}
I am not able to upload the byte array. Parse cloud function (in main.js) always fails with error code 141.
Could someone please have a look and help me in resolving this issue?

how to access a file on the client's machine

I have a few clients that will be using my website, and I want each client to have their own "config" file (EX: location=1 for one computer, location=2 for another). I want to do this using a file I place on the client's machine and then when they access the website the client looks on their own machine and figures out what to load based on what's in that file. This file can be a CSV file, plain text file, or any other kind of file that it needs to be for this to work.
Looking online all I've seen is stuff with file uploader. I don't want them to have to select the file, just have the file contents load and call a javascript function when they do.
Example of file
Location=1
AnswerToQuestion=42
and another file
Location=2
AnswerToQuestion=15
and my JS function
var setAnswerToQuestion = function(answer){
locationConfig.setAnswer(answer)
}

Take a look at localstorage. It's a persistent key/value system that the browser implements to keep data for your website/webapp.
The Basic Principle:
To set a variable:
localStorage.setItem('answer_1', '42');
To get a variable:
localStorage.getItem("answer_1");
I guess if you have lots of answers you would end up with an array/object something like this:
var answers = [42, 15];
Towards a Solution:
You could store and retrieve that by using JSON.stringify
localStorage.setItem('answers', JSON.stringify(answers));
var answers = JSON.stringify(localStorage.getItem('answers'));
Be Educated
Smashing Magazine has a tutorial here
Dive into HTML5 has a tutorial here

You can't access files on local machines without using "file upload". You could store your config files on browser localstorage as:
var getConfigData = function() {
return JSON.parse(localStorage.getItem('config'));
}
var saveConfigData = function(config) {
localStorage.setItem('config', JSON.stringify(config));
}
var addDataToConfig = function(key, value) {
var config = getConfigData();
config[key] = value;
saveConfigData(config);
}
var config = {
Location: 1,
AnswerToQuestion: 42
};
// save new config
saveConfigData(config);
// add new data to config
addDataToConfig('name', 'John Doe');