Garmin IQ does not support dynamic units setting for FIT Developer Fields

I developed the app for windsurfing session recording: https://apps.garmin.com/en-US/apps/9d47be43-2724-44e4-8f5e-3005b0766087

The app supports runtime setting for speed units (km/h or knots) and also, some speed values are written to FIT file as Developer Fields. The problem that Garmin Connect displays the units for Developer Fields from fitcontributions.xml file, so I can choose either "knots" or "km/h" at compile time, and changing the unit in the app does not change them in Garmin Connect. At the same time, I can see that FIT file contains those units that were stated during session creation. I.e. If I use units=>"knots" in the code below, then FIT file will contain "knots", so this can be set at runtime.

best100Field = session.createField("best_100m", BEST100_FIELD_ID, FitContributor.DATA_TYPE_FLOAT,
{:mesgType=>FitContributor.MESG_TYPE_SESSION, :units=>"knots"}
);

As per my understanding, the issue can be fixed if the units values for Garmin Connect are taken from the FIT file instead of fitcontributions.xml. Please advise if I should file the bug report for this or perhaps there is some other solution.

0 jim_m_58 over 5 years ago

That's the way it works. The contents of fitcontributions is included when you build an iq file, and when that data is displayed in GC, the info is pulled from the app store. Your app doesn't define things. what's in the app store defines it.

0 VitVas over 5 years ago

jim_m_58 said:
Your app doesn't define things. what's in the app store defines it.

Thank you for prompt reply. I understand that it works as is for now. However it looks like limitation from the user perspective. And then it's not quite clear the sense of setting ":units=>xxx" in the the createField, if they're ignored by GC.

0 flowstate over 5 years ago in reply to VitVas

I think the reason it works this way is to support multiple languages for the labels and units, although I have to admit I wish dynamic labels and units were allowed, too.

As for setting the units in createField, that's probably to comply with the FIT file standard. I agree from our perspective it doesn't add anything, except maybe for compatibility with non-garmin sites.

One workaround would be to write the selected units as a session value, although this will consume a bit of memory/code.

0 jim_m_58 over 5 years ago in reply to VitVas

It's in the .fit file and could be used by other sites. Same with the case of native field numbers.

It's been this way for years and changing it would be a pretty big change.

0 flowstate over 5 years ago in reply to jim_m_58

One proposal would be to allow dev to set a given field's label or units to "use FIT value" in the app manifest / resources, instead of specifying a string. That would preserve backwards compatibility while allowing for this extended functionality.

I doubt it'll happen though.

0 VitVas over 5 years ago

jim_m_58, FlowState,

Thank you for your clarifications. It's understood now.

0 flowstate over 5 years ago in reply to VitVas

Another workaround would be to have 2 FIT fields: one for knots and one for km/h. Only create/write the one that's applicable.

Ofc this kind of approach only works when the various units/metrics are known at compile-time (which is the majority of cases -- although I have an app where it's not the case).

0 VitVas over 5 years ago in reply to flowstate

flowstate said:
Another workaround would be to have 2 FIT fields: one for knots and one for km/h. Only create/write the one that's applicable.

Right! It worth to try. Thanks!

0 flowstate over 5 years ago in reply to VitVas

No worries. If you want to "officially" suggest your idea to Garmin, you can use this page:

https://www.garmin.com/en-US/forms/ideas/

(I have no idea how effective this is.)

Personally I think it would be great to be able to opt-in to using a label or unit from FIT on a case-by-case basis.