firebase - 如何在 Firebase 实时数据库中保存 LocalData?
问题描述
我是使用 Kotlin 和编程的新手,我目前正在制作带有事件的日历。当我想将这些事件连接到 firebase 时,我的问题就来了。
我正在使用我在 git ( https://github.com/kizitonwose/CalendarView ) 中找到的一个示例,该示例使用 ThreeTen 库作为日期。这是事件对象:
class Event (val id: String, val text: String, val date: LocalDate) : Serializable
数据变量属于 LocalData 类型,这就是导致我出现问题的原因,因为 Firebase 似乎只接受 String、Int 等类型的变量......
我尝试使用 toString 和 Gson() 将变量传递给 String,但没有成功。
如果有帮助,这是代码
private val inputDialog by lazy {
val editText = AppCompatEditText(requireContext())
val layout = FrameLayout(requireContext()).apply {
// Setting the padding on the EditText only pads the input area
// not the entire EditText so we wrap it in a FrameLayout.
setPadding(20, 20, 20, 20)
addView(editText, FrameLayout.LayoutParams(MATCH_PARENT, WRAP_CONTENT))
}
AlertDialog.Builder(requireContext())
.setTitle(getString(R.string.example_3_input_dialog_title))
.setView(layout)
.setPositiveButton(R.string.save) { _, _ ->
saveEvent(editText.text.toString())
// Prepare EditText for reuse.
editText.setText("")
}
.setNegativeButton(R.string.close, null)
.create()
.apply {
setOnShowListener {
// Show the keyboard
editText.requestFocus()
context.inputMethodManager.toggleSoftInput(InputMethodManager.SHOW_FORCED, 0)
}
setOnDismissListener {
// Hide the keyboard
context.inputMethodManager.toggleSoftInput(InputMethodManager.HIDE_IMPLICIT_ONLY, 0)
}
}
}
private var selectedDate: LocalDate? = null
private val today = LocalDate.now()
private val titleSameYearFormatter = DateTimeFormatter.ofPattern("MMMM")
private val titleFormatter = DateTimeFormatter.ofPattern("MMM yyyy")
private val selectionFormatter = DateTimeFormatter.ofPattern("yyyy MM dd")
private val events = mutableMapOf<LocalDate, List<Event>>()
private var prueba = Gson().toJson(events)
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
return inflater.inflate(R.layout.fragment_calendar, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
mDatabaseReference = mDatabase!!.reference.child("events")
exThreeRv.layoutManager = LinearLayoutManager(requireContext(), RecyclerView.VERTICAL, false)
exThreeRv.adapter = eventsAdapter
exThreeRv.addItemDecoration(DividerItemDecoration(requireContext(), RecyclerView.VERTICAL))
val daysOfWeek = daysOfWeekFromLocale()
val currentMonth = YearMonth.now()
exThreeCalendar.setup(currentMonth.minusMonths(10), currentMonth.plusMonths(10), daysOfWeek.first())
exThreeCalendar.scrollToMonth(currentMonth)
if (savedInstanceState == null) {
exThreeCalendar.post {
// Show today's events initially.
selectDate(today)
}
}
class DayViewContainer(view: View) : ViewContainer(view) {
lateinit var day: CalendarDay // Will be set when this container is bound.
val textView = view.exThreeDayText
val dotView = view.exThreeDotView
init {
view.setOnClickListener {
if (day.owner == DayOwner.THIS_MONTH) {
selectDate(day.date)
}
}
}
}
exThreeCalendar.dayBinder = object : DayBinder<DayViewContainer> {
override fun create(view: View) = DayViewContainer(view)
override fun bind(container: DayViewContainer, day: CalendarDay) {
container.day = day
val textView = container.textView
val dotView = container.dotView
textView.text = day.date.dayOfMonth.toString()
if (day.owner == DayOwner.THIS_MONTH) {
textView.makeVisible()
when (day.date) {
today -> {
textView.setTextColorRes(R.color.white)
textView.setBackgroundResource(R.drawable.today_bg)
dotView.makeInVisible()
}
selectedDate -> {
textView.setTextColorRes(R.color.white)
textView.setBackgroundResource(R.drawable.selected_bg)
dotView.makeInVisible()
}
else -> {
textView.setTextColorRes(R.color.black)
textView.background = null
dotView.isVisible = events[day.date].orEmpty().isNotEmpty()
}
}
} else {
textView.makeInVisible()
dotView.makeInVisible()
}
}
}
exThreeCalendar.monthScrollListener = {
requireActivity().home.text = if (it.year == today.year) {
titleSameYearFormatter.format(it.yearMonth)
} else {
titleFormatter.format(it.yearMonth)
}
// Select the first day of the month when
// we scroll to a new month.
selectDate(it.yearMonth.atDay(1))
}
class MonthViewContainer(view: View) : ViewContainer(view) {
val legendLayout = view.legendLayout
}
exThreeCalendar.monthHeaderBinder = object : MonthHeaderFooterBinder<MonthViewContainer> {
override fun create(view: View) = MonthViewContainer(view)
override fun bind(container: MonthViewContainer, month: CalendarMonth) {
// Setup each header day text if we have not done that already.
if (container.legendLayout.tag == null) {
container.legendLayout.tag = month.yearMonth
container.legendLayout.children.map { it as TextView }.forEachIndexed { index, tv ->
tv.text = daysOfWeek[index].name.first().toString()
tv.setTextColorRes(R.color.black)
}
}
}
}
exThreeAddButton.setOnClickListener {
inputDialog.show()
}
}
private fun selectDate(date: LocalDate) {
if (selectedDate != date) {
val oldDate = selectedDate
selectedDate = date
oldDate?.let { exThreeCalendar.notifyDateChanged(it) }
exThreeCalendar.notifyDateChanged(date)
updateAdapterForDate(date)
}
}
private fun saveEvent(text: String) {
if (text.isBlank()) {
Toast.makeText(requireContext(),
R.string.example_3_empty_input_text, Toast.LENGTH_LONG).show()
} else {
selectedDate?.let {
events[it] = events[it].orEmpty().plus(
Event(
UUID.randomUUID().toString(),
text,
it
)
)
uploadFirebase()
updateAdapterForDate(it)
}
}
}
private fun deleteEvent(event: Event) {
val date = event.date
events[date] = events[date].orEmpty().minus(event)
updateAdapterForDate(date)
}
private fun updateAdapterForDate(date: LocalDate) {
eventsAdapter.events.clear()
eventsAdapter.events.addAll(events[date].orEmpty())
eventsAdapter.notifyDataSetChanged()
exThreeSelectedDateText.text = selectionFormatter.format(date)
}
fun uploadFirebase(){
val newEvent = mDatabaseReference.push()
newEvent.setValue(events)
}
override fun onStart() {
super.onStart()
}
override fun onStop() {
super.onStop()
}
}
解决方案
您无法LocalDate
在 Firebase 实时数据库中添加类型属性,因为它不是受支持的数据类型。但是,有两种方法可以解决此问题:
您将日期保存为
ServerValue.TIMESTAMP
,这基本上意味着您保存自 Unix 纪元以来经过的秒数。在这种情况下,服务器将当前日期写入数据库。为此,请参阅我在以下帖子中的回答:您为日期字段指定自定义
long
值。在这种情况下,由您决定写入的日期。
不幸的是,您无法将这两个选项结合起来,您可以使用其中一个。
在谈论 aLocalDate
时,我们通常会谈论偏移量,在这种情况下,我会这样做。如第一点所述,我将存储一个 Timestamp 属性,该属性将让服务器填充服务器时间戳,以及一个偏移量属性,该属性应该以天/小时为单位填充偏移量。
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