Can't figure out how to get write access to work - nest-api

Question

I'm talking to Nest Cloud API using Nodejs using firebase node module. I'm using accessToken that I got from https://api.home.nest.com/oauth2/access_token, and this seems to work. My Nest user account got prompted to "accept" this request, which I did and my app is listed in the Nest Account "Works with Nest" page so all looks good. I use this accessToken in call to authWithCustomToken and that works and my Nodejs application requested read/write permission (See https://developers.nest.com/products/978ea6e2-c301-4dff-8b38-f63d80757162). And reading the Nest thermostat properties from https://developer-api.nest.com/devices/thermostats/[deviceid] works, but when I try and write to hvac_mode like this:
this.firebaseRef = new Firebase("https://developer-api.nest.com");
this.myNestThermostat = this.firebaseRef.child("devices/thermostats/"+deviceId);
this.myNestThermostat.set("{'hvac_mode': 'off'}", function (error) { ... }
and this always returns:
FIREBASE WARNING: set at /devices/thermostats/fwxNBtjaok6KZJbSXhf2azuBmGSvkcjK failed: No write permission(s) for field(s): /devices/thermostats/fwxNBtjaok6KZJbSXhf2azuBmGSvkcjK
(where the deviceId is what I see when I enumerate my devices, I only have one, so I'm pretty sure it is correct).
Any ideas?

Answer 1

Well, isn't that always the case, I found an answer already. Turns out if I create a firebase reference to the property itself like this:
var propertyRef = this.myNestThermostat.child(name);
Then the following succeeds:
propertyRef.set(value, function (error) { ...
The firebase documentation was misleading on this because it led me to believe I could write this:
this.myNestThermostat.set("{'hvac_mode': 'off'}", function (error) { ... }
which technically should have worked, but I guess that would mean I'd need write access on the whole of this.myNestThermostat, which I don't. Tricky.
Anyway I'm happy because it works now, yay! Firebase + nodejs rocks!