TrivialDrive | In-app Purchase Sample

Code A is right, since not the data from database is returned but an observable data class holder (LiveData), this will be returned even if there is no record in the table. You can then attach an Observer to this observable, the observer will be triggered once changes to database occur w.r.t. your query (You can find several examples for this in the Android Documentation). The getValue() method of a LiveData object can return null though, if no value has been set yet, but usually you use Observers for changes of the LiveData.

Kotlin - Property initialization using "by lazy" vs. "lateinit"

I believe the answer lies in this thread and precisely below point.

lateinit var can be initialized from anywhere the object is seen from, e.g. from inside a framework code, and multiple initialization scenarios are possible for different objects of a single class. by lazy { ... }, in turn, defines the only initializer for the property, which can be altered only by overriding the property in a subclass. If you want your property to be initialized from outside in a way probably unknown beforehand, use lateinit.

This usually happens when the parent activity implements onActivityResult() and completely consumes it without returning it. In the fragment's activity make sure you return onActivityResult whenenver you implement it. for example. Inside your activity, you can implement onActivityResult as follows: