Firebase-如何一次删除多个条目？-Firebase-Howtodeletemanyentriesatonce?

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In order to delete multiple entries from your database, you need to know all those locations (refernces). So with other words, in the way you add data, you should also delete it.

要从数据库中删除多个条目，您需要知道所有这些位置（参考）。换句话说，在添加数据的方式中，您也应该删除它。

Assuming your database looks like this:

假设您的数据库如下所示：

Firebase-root
   |
   --- Users
   |     |
   |     --- userUid1
   |     |      |
   |     |      --- //user1 data
   |     |
   |     --- userUid2
   |            |
   |            --- //user2 data
   |
   --- Groups
         |
         --- groupId1
         |      |
         |      --- //group1 data
         |      |
         |      --- Users
         |            |
         |            --- userUid1: true
         |            |
         |            --- userUid3: true
         |
         --- groupId2
                |
                --- //group2 data

I suggest you using the method below:

我建议你使用以下方法：

private static void deleteUser(String userId, String groupId) {
    Map map = new HashMap<>();
    map.put("/Users/" + userId + "/", null);
    map.put("/Groups/" + groupId + "/Users/" + userId + "/", new HashMap<>().put(userId, null));
    //other locations
    databaseReference.updateChildren(map);
}

This method atomically deletes all those entries. Using these paths, you can perform simultaneous updates to multiple locations in the JSON tree with a single call to deleteUser() method. Simultaneous deletes made this way are atomic: either all updates succeed or all updates fail.

此方法以原子方式删除所有这些条目。使用这些路径，您只需调用deleteUser（）方法，即可同时更新JSON树中的多个位置。以这种方式同时删除是原子的：要么所有更新都成功，要么所有更新都失败。

Hope it helps.

希望能帮助到你。