Nullability and LiveData with Kotlin

Question

I want to use LiveData with Kotlin and have values that should not be null. How do you deal with this? Perhaps a wrapper around LiveData? Searching for good patterns here .. As

Answer 1

This is my solution.

class NotNullLiveData
constructor(private val default: T) : MediatorLiveData() {
    override fun getValue(): T {
        return super.getValue() ?: default
    }

    override fun setValue(value: T) {
        super.setValue(value)
    }
}

@MainThread
fun  mutableLiveDataOfNotNull(initValue: T): NotNullLiveData {
    val liveData = NotNullLiveData(initValue)
    liveData.value = initValue
    return liveData
}

@MainThread
fun  mutableLiveDataOf(initValue: T): MutableLiveData {
    val liveData = MutableLiveData()
    liveData.value = initValue
    return liveData
}


fun  LiveData.toNotNull(default: T): NotNullLiveData {
    val result = NotNullLiveData(default)
    result.addSource(this) {
        result.value = it ?: default
    }
    return result
}