为什么我要删除child_added事件？ [英] Why do I get child_added event on remove?

问题描述

下面的代码产生了一个重复的child_added的无限循环，尽管我从来没有添加一个孩子。节点被删除。我只是永远循环。

  //通知分支是预先填充的，当我到达这里时：
 notifications.startAt （null）.on（'child_added'，processNotification，logError）; 
 
函数processNotification（通知）
 {
 removeNotification（notification）; 
 
 
函数removeNotification（通知）
 {
 var child = notifications.child（notification.name（））; 
 console.log（REMOVING，child.toString（））; 
 child.remove（）; 
 
 $ / code> 

我记录的是相同的四个节点（A，B，C，D ）被删除：



 删除https://my.firebaseio.com/experimental/-JVMi0_4poXfOWUt5g49  -  A 
 REMOVING https://my.firebaseio.com/experimental/-JVMi1Y_bFwZAkffRel4  -  B 
删除https://my.firebaseio.com/experimental/-JVMi2lyhKj8z27ik71x  -  C 
删除https：//my.firebaseio。 com / experimental / -JVMhzazdgHYAstqxu8L  -  D 
 REMOVING https://my.firebaseio.com/experimental/-JVMi0_4poXfOWUt5g49  -  A 
 REMOVING https://my.firebaseio.com/experimental/-JVMi1Y_bFwZAkffRel4  -  B 
 REMOVING https://my.firebaseio.com/experimental/-JVMi2lyhKj8z27ik71x  -  C 
 REMOVING https://mu.firebaseio.com/experimental/-JVMhzazdgHYAstqxu8L  -  D 
 ... 
  




解决方案

最终，我放弃了查询并使用正常处理，删除startAt（null）：



  notifications.on（'child_added'，processNotific ation，logError）; 
  

行为与文档不同，但startAt（null）不行产生相同的行为（虽然在它应该）。我很乐意看到这个更好的记录。


The following code produces an endless loop of repeated child_added, though I never add a child. The nodes are removed. I just loop forever. How can I fix this?

//notifications branch is pre-populated when I get here:
notifications.startAt(null).on('child_added', processNotification, logError);

function processNotification(notification)
{
    removeNotification(notification);
}

function removeNotification(notification)
{
    var child = notifications.child(notification.name());
    console.log("REMOVING", child.toString());
    child.remove();     
}

What I log is the same four nodes (A,B,C,D) being removed:

REMOVING https://my.firebaseio.com/experimental/-JVMi0_4poXfOWUt5g49 - A
REMOVING https://my.firebaseio.com/experimental/-JVMi1Y_bFwZAkffRel4 - B
REMOVING https://my.firebaseio.com/experimental/-JVMi2lyhKj8z27ik71x - C
REMOVING https://my.firebaseio.com/experimental/-JVMhzazdgHYAstqxu8L - D
REMOVING https://my.firebaseio.com/experimental/-JVMi0_4poXfOWUt5g49 - A
REMOVING https://my.firebaseio.com/experimental/-JVMi1Y_bFwZAkffRel4 - B
REMOVING https://my.firebaseio.com/experimental/-JVMi2lyhKj8z27ik71x - C
REMOVING https://mu.firebaseio.com/experimental/-JVMhzazdgHYAstqxu8L - D
...

解决方案

Ultimately, I just dropped the query and went with normal processing, dropping the "startAt(null)":

notifications.on('child_added', processNotification, logError);

It's not obvious that the behavior will be different from the documentation, but the startAt(null) does not produce the same behavior (though in thoery it should). I would love to see this better documented.

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