Sometimes, the JSON data you receive may contain keys with values such as null, 0, or empty arrays.
These cases can have different meanings depending on the context. For instance, a null value may indicate that the device was unable to extract data for that key at the time of collection, or that the specific functionality is not supported on that version of the wearable. Similarly, some keys might not appear at all if the feature isn’t compatible with the device or isn't available from the data source. A value of 0 is typically used when no measurable activity or data was detected for that particular metric, such as zero steps or inactive heart rate data.
It’s important to note that this behavior can vary depending on both the wearable model and the data source itself, as not all platforms share the same metrics. For more detailed insights into this behavior and to verify whether a specific key is expected to be delivered by a data source, you can refer to The Ultimate Guide to Data Source Particularities