Espruino/Wifi - getIP() returns undefined but callback receives null,ip

[espruino-discuss]

Posted at 2017-09-04 by @allObjects

Setup is as documented (and required to start with saved code after power on:

var WIFI_NAME = "mySSID";
var WIFI_OPTIONS = { password : "mySSIDPassword" };
var wifi = null;

function onInit() {
  wifi = require("EspruinoWiFi");
  wifi.connect(WIFI_NAME, WIFI_OPTIONS, function(err) {
    if (err) {
      console.log("Connection error: "+err);
      return;
    }
    console.log("Connected!");
    console.log("getIP() returned: ",wifi.getIP(function(val){ console.log("getIP() in callback: ",val); }));
  });
}

Console:

 _____                 _
|   __|___ ___ ___ _ _|_|___ ___
|   __|_ -| . |  _| | | |   | . |
|_____|___|  _|_| |___|_|_|_|___|
          |_| http://espruino.com
 1v94 Copyright 2016 G.Williams
>
=undefined
>save()
=undefined
Erasing Flash...
Writing..........................
Compressed 114368 bytes to 23555
Checking...
Done!
Running onInit()...
Connected!
getIP() returned:  undefined
getIP() in callback:  null
> 

Even executed much later, I get the same undefined / null.

[espruino-discuss]

Posted at 2017-09-04 by @gfwilliams

That's as you'd expect I think?

/* Get the IP and MAC address when connected to an AP and call 
`callback(err, { ip : ..., mac : ...})`. If err isn't null,
it contains a string describing the error. This doesn't work
when only in AP mode (the IP address is always 192.168.4.1)
*/
exports.getIP = function (callback) { ... }

So it's that there are two arguments returned by the callback - err and ip. It's odd, but it's just the way node.js tended to handle callback functions that can return an error, so I wanted to keep things compliant with them.

Since on EspruinoWiFi the WiFi is basically async, getIP can't immediately return an IP address.

Unfortunately when running on ESP8266 the callback format is different - it's something I'd like to change to bring everything more in-line really.

---

Posted at 2017-09-04 by @allObjects

doooh... me... sorry bothering you for the callback... now I recall that the first argument is the error, and if first argument - error - is null, second argument is the actual data...

I adjusted my code and it does what I needed. THANKS...

Adjusted with 'assuming' I get no err(or) in getIP():

...
  wifi.getIP(function(err,data){ console.log("getIP() in callback: ",data.ip); }));
...

with console output:

...
Running onInit()...
Connected!
getIP() in callback:  192.168.0.113
>