Custom MutableLiveData that operate just once.

OperationLiveData.kt

class OperationLiveData<T>(private val operation: OperationLiveData<T>.() -> Unit) : MutableLiveData<T>() {

    private var operated = AtomicBoolean(false)

    override fun observe(owner: LifecycleOwner, observer: Observer<in T>) {
        super.observe(owner, observer)

        operate()
    }

    override fun observeForever(observer: Observer<in T>) {
        super.observeForever(observer)

        operate()
    }

    private fun operate() {
        if (value != null && operated.get()) {
            return
        }

        operation()
        operated.set(true)
    }
}