Accessing Weather.CurrentConditions.observationLocationPosition causes app crash on some devices

I'm struggling with crashes on seemingly random devices of this simple code:

if (Toybox has :Weather) {
	if (Toybox.Weather has :getCurrentConditions) {
		var w = Weather.getCurrentConditions();
		if (Toybox.Weather.CurrentConditions has :observationLocationPosition) {
			if (w.observationLocationPosition != null) {
				lastLocation = w.observationLocationPosition;
			}
		}
	}
}

It work on 99% of devices, but a few users get the following error:

Error: Unexpected Type Error
Details: 'Failed invoking <symbol>'
Time: 2021-11-01T13:29:19Z
Part-Number: 006-B3291-00
Firmware-Version: '19.20'
Language-Code: dut
ConnectIQ-Version: 4.0.6

It fails at these lines (some error code points to if, some to ne 2nd line):

if (w.observationLocationPosition != null) {
lastLocation = w.observationLocationPosition;
}

I already ckeck all "has" conditions I could think of, and still it fails for some users. It works on 2 of my watches and in all simulators - it is real devices that have a problem. Any way to avoid it? Thanks!

Top Replies

FlowState over 3 years ago +1 verified

As per the docs, Weather.getCurrentConditions() can return null, so you need to check w for null in your code. From my reading (between the lines) of the docs, it seems that you don't need all of those…

All Replies

+1 FlowState over 3 years ago

As per the docs, Weather.getCurrentConditions() can return null, so you need to check w for null in your code. From my reading (between the lines) of the docs, it seems that you don't need all of those has checks either. Seems to me Weather will always have getCurrentConditions() and CurrentConditions will always have observationLocationPosition.

I think you could rewrite the whole thing as:

if (Toybox has :Weather) {
		var currentConditions = Weather.getCurrentConditions();
        if (currentConditions != null && currentConditions.observationLocationPosition != null) {
            lastLocation = currentConditions.observationLocationPosition;
        }
	}
}

0 MobileDriveway over 3 years ago in reply to FlowState

Thanks! You might be right - I knew I needed a second set of eyes :)). And those "has" were just me trying to trap the issue in any possible way...

0 jim_m_58 over 3 years ago in reply to MobileDriveway

getCurrentConditions will be null if the device hasn't gotten data yet. same with the forecasts, This would be the case if you first turn on your device and it isn't connected to the phone.

You want to use "has" as even if you seta min API level of 3.2.x, as some 3.2 devices like the f5+ don't have weather.

0 FlowState over 3 years ago in reply to jim_m_58

As implied in my code example, the suggestion was that the single top-level has check ("Toybox has :Weather") should be sufficient, as opposed to 3 nested has checks in the OP's example.

0 MobileDriveway over 3 years ago in reply to jim_m_58

Thanks. That is a good idea for test scenario - restart the watch with phone disconnected.

0 MobileDriveway over 3 years ago in reply to MobileDriveway

Yes, checking "has :Weather" is a given. All other "has" checks I added out of frustration from getting 'Failed invoking <symbol>' error - couldn't understand which symbol was missing...

0 jim_m_58 over 3 years ago in reply to MobileDriveway

It costa a few bytes of memory, but you may want to do the has in initialize() and set a boolean that's checked elsewhere.

The reason being is that checking a boolean is cheaper than checking a dictionary (that's what "has" does), so a cheaper operation each time onUpdate runs. I only ever do "has" in class initialization, as it will not change as the app runs.

0 prenard59115 over 2 years ago in reply to MobileDriveway

Hello.

I have exactly the same problem...

Did you fix your problem ? How ?

Thanks for your help.

0 jim_m_58 over 2 years ago in reply to prenard59115

Not all devices with CIQ 3.2 have Weather - The F5+ devices for example.

You want to do "has" checks in your code, and when you get things like currentConditions, you also want to null check the value. It could be the devices doesn't have the data. You also want to null check the values, as anything in currentConditions can be null.. You also whar to have the position permission set for some things or they will always be null (observationLocationPosition for example)

0 MobileDriveway over 2 years ago in reply to prenard59115

prenard59115 said:
I have exactly the same problem...

Did you fix your problem ? How ?

Thanks for your help.

Yes. As was suggested by FlowState, getCurrentConditions() and all lower values can return null, so you have to check for it:

if (Toybox has :Weather) {
var currentConditions = Weather.getCurrentConditions();
if (currentConditions != null && currentConditions.observationLocationPosition != null) {
lastLocation = currentConditions.observationLocationPosition;}}}