Firebase ServerValue#TIMESTAMP 与 updateChildren()答案

【问题标题】：Firebase ServerValue#TIMESTAMP with updateChildren()Firebase ServerValue#TIMESTAMP 与 updateChildren()
【发布时间】：2019-07-31 22:29:07
【问题描述】：

我有这个映射器，它执行以下操作：

override fun map(model: Model) = mapOf<String, Any?>(
  ...,
  KEY_TIMESTAMP to (model.timestamp.takeIf { it > -1 } ?: ServerValue.TIMESTAMP),
  ...
)

当我需要将更多模型同时发布到不同的位置时，我会使用映射器并将模型转换为 Map<String, Any?>。所以我有一堆地图，然后合并到一个大的Map<String, Any?> 看起来像这样：

{
   "messages/-L_bXQUibioB6OMkl0SE/text": "Android Developer created this conversation",
   "messages/-L_bXQUibioB6OMkl0SE/senderName": "system",
   "messages/-L_bXQUibioB6OMkl0SE/senderAvatarUrl": null,
   "messages/-L_bXQUibioB6OMkl0SE/timestamp/.sv": "timestamp",
   "messages/-L_bXQUibioB6OMkl0SE/attachment": null,
   "chats/participants/UZ684hcHTnOkaglUX0QwbR9DK442/name": "cool guy",
   "chats/participants/UZ684hcHTnOkaglUX0QwbR9DK442/imageUrl": null,
   "chats/participants/aqiTRMAUOSdJIuEOvNJpeAb4D0F3/name": "Android Developer",
   "chats/participants/aqiTRMAUOSdJIuEOvNJpeAb4D0F3/imageUrl": "https://firebasestorage...",
   "chats/lastMessage": "Android Developer created this conversation",
   "chats/lastMessageTimestamp/.sv": "timestamp",
   "chats/name": null,
   "chats/imageUrl": null,
   "chats/type": "SINGLE"
}

那么我就这样做了：

ovveride fun updateChildren(data: Map<String, Any?>) = Completable.create { emitter ->
    rootRef.updateChildren(data) { databaseError, _ ->
        databaseError?.toException()
            ?.let(emitter::onError)
            ?: emitter.onComplete()
    }
}

当最后一个代码被调用时，我得到了以下异常：

com.google.firebase.database.DatabaseException: Path '/messages/-L_bXQUibioB6OMkl0SE/timestamp/.sv' contains disallowed child name: .sv
        at com.google.firebase.database.core.utilities.Validation.parseAndValidateUpdate(com.google.firebase:firebase-database@@16.0.5:140)
        at com.google.firebase.database.DatabaseReference.updateChildrenInternal(com.google.firebase:firebase-database@@16.0.5:428)
        at com.google.firebase.database.DatabaseReference.updateChildren(com.google.firebase:firebase-database@@16.0.5:418)

如果可能的话，我怎样才能解决这个问题并继续使用 ServerValue.TIMESTAMP？

【问题讨论】：

标签： android firebase firebase-realtime-database timestamp

【解决方案1】：

因为这行：

"messages/-L_bXQUibioB6OMkl0SE/timestamp/.sv": "timestamp"

应该是这样的：

"messages/-L_bXQUibioB6OMkl0SE/timestamp": {
    ".sv": "timestamp"
}

错误在我的地图合并方法中最简单的解决方法是过滤此类属性：

lateinit var entry: MutableMap.MutableEntry<String, Any?>
while (map.entries.find { it.key.endsWith(".sv") }?.apply { entry = this } != null) {
    map.remove(entry.key)
    map[entry.key.removeSuffix("/.sv")] = ServerValue.TIMESTAMP
}

return realtimeDatabase.updateChildren(map)

【讨论】：

很好看的@GV_FiQst！