I keep getting a null returned when I retrieve a timestamp in Firestore:
I have a collection appData with a document appDataRefreshTimestamp and field lastRefreshTimestamp (the app looks at this and compares to stored value in SharedPreferences in order to force refresh on specific AppData) as below:
I am trying to retrieve this here:
fun listenForAppDataRefreshTimestamp() : LiveData<Boolean> {
val result = MutableLiveData<Boolean>()
result.value = false
val lastTimeDataCached = Utils.getTimestampFromSharedPreferences(PREFERENCE_TIMESTAMP_APP_DATA_REFRESH)
Log.d(TAG, "listenForAppDataRefreshTimestamp() - last saved time stamp: $lastTimeDataCached")
appDataTimestamp
.addSnapshotListener{ docSnapshot, e ->
if (e != null) {
Log.w(TAG, "Listen failed.", e)
return@addSnapshotListener
}
if (docSnapshot != null) {
val newTimestamp = docSnapshot.getTimestamp("lastRefreshTimestamp")?.toDate()
if (lastTimeDataCached != null) {
if (lastTimeDataCached < newTimestamp){ //newTimestamp is null!!
Log.d(TAG, "listenForAppDataRefreshTimestamp() - New Timestamp found ($newTimestamp)")
newTimestamp?.let { Utils.saveTimestamp(APP_DATA_DATA_REFRESH_TIMESTAMP,it) }
result.postValue(true)
}
}
Log.d(TAG, "listenForAppDataRefreshTimestamp() - Saved date is.................. ${Utils.getTimestampFromSharedPreferences(PREFERENCE_TIMESTAMP_APP_DATA_REFRESH)}")
}
}
return result
}But as shown above, it is null and I can't see why..
Edit: I have now added the SharedPreferences element - it seems it is this that may be causing the issue (not saving the timestamp for some reason).
I have the following two functions in my Utils class:
fun saveTimestamp(timestampKey: String, timestamp: Date) {
val sharedPref = getSharedPreferences()
val editor = sharedPref.edit()
editor.putLong(timestampKey, timestamp.time)
editor.apply()
}And
fun getTimestampFromSharedPreferences(timestampKey: String): Date? {
val currentTimestamp = System.currentTimeMillis()
val sharedPref = getSharedPreferences()
val timestamp = sharedPref.getLong(timestampKey, currentTimestamp)
Log.d(TAG, "getTimestampFromSharedPreferences($timestampKey) = $currentTimestamp")
return if (timestamp.equals(0)) Date(currentTimestamp)
else Date(timestamp)
}But in listenForAppDataRefreshTimestamp() it shows the timestamp didn't get updated in SharedPreferences when it is checked here:
Log.d(TAG, "listenForAppDataRefreshTimestamp() - Saved date is.................. ${Utils.getTimestampFromSharedPreferences(PREFERENCE_TIMESTAMP_APP_DATA_REFRESH)}") // Still the old timestamp..