Firebase的云端函数：如何取得event.data.ref.parent.child（" xxx" val？）？ [英] Cloud Functions for Firebase: How to get event.data.ref.parent.child("xxx").val?

问题描述

我在Firebase上有这样的结构：

 会员
 |  -  -kSjJSDFjl2DFc 
 |  -  isDeleted：true 
 |  - 性别：male
  

，我写道：

  exports.doMemberDeletion = functions.database.ref（/ members / {memberId} / isDeleted）。 onWrite（event => {
 const isDeleted = event.data.val（）; 
 
 if（isDeleted）{
 const gender = event.data.ref.parent。 child（gender）.val; //错误在这里
 console.log（已删除一个+ gender +member）; 
} 
}）; 
  

然而，在 event.data.ref.parent.child （）.val ，请告诉如何在这种情况下获取值。谢谢！

解决方案

DeltaSnapshot 中提供的事件数据仅适用于匹配的位置。树或兄弟姐妹中较高的数据不可用。如果你的会员数据不是很大，以至于你不想听任何改变，你可以这样做：

  //在树中监听高一级
 exports.doMemberDeletion = functions.database.ref（/ members / {memberId}）。onWrite（event => {
 const wasDeleted = event.data .previous.child（'isDeleted'）。val（）; 
 const isDeleted = event.data.current.child（'isDeleted'）。val（）; 
 
 if（！wasDeleted && isDeleted）{
 const gender = event.data.current.child（'gender'）。val（）; 
 console.log（Deleted a+ gender +member） ; 
} 
}）; 
  

您的原始方法也适用，但需要提取性别数据：

  exports.doMemberDeletion = functions.database.ref（/ members / {memberId} / isDeleted）。onWrite（event => {
常量isDeleted = event.data.val（）; 
 
 if（isDeleted）{
 //如Jen Person的答案中所述，使用adminRef进行无限制访问
返回事件。 data.adminRef.parent.child（'gender'）。once（'value'）。then（（snapshot）=> {
 console.log（Deleted a+ snapshot.val（）+member ）; 
}）; 
} 
}）; 
  

I'm having a structure on Firebase like this:

members
 |- -kSjJSDFjl2DFc
          |- isDeleted: true
          |- gender: "male"

In my cloud function, I wrote:

exports.doMemberDeletion = functions.database.ref("/members/{memberId}/isDeleted").onWrite(event => {
    const isDeleted = event.data.val();

    if (isDeleted) {
        const gender = event.data.ref.parent.child("gender").val; // Error here
        console.log("Deleted a " + gender + " member");
    }
});

However, it gives error on event.data.ref.parent.child().val, please advise how to get the value in this case. Thanks!

解决方案

The DeltaSnapshot provided in the event data is for the matched location only. Data higher in the tree or in siblings is not available. If your member data is not so large that you're concerned about listening for changes to any of it, you could do this:

// listen one level higher in tree    
exports.doMemberDeletion = functions.database.ref("/members/{memberId}").onWrite(event => {
    const wasDeleted = event.data.previous.child('isDeleted').val();
    const isDeleted = event.data.current.child('isDeleted').val();

    if (!wasDeleted && isDeleted) {
        const gender = event.data.current.child('gender').val();
        console.log("Deleted a " + gender + " member");
    }
});

Your original approach also works, but requires a fetch of the gender data:

exports.doMemberDeletion = functions.database.ref("/members/{memberId}/isDeleted").onWrite(event => {
    const isDeleted = event.data.val();

    if (isDeleted) {
        // as noted in Jen Person's answer, use adminRef for unrestricted access
        return event.data.adminRef.parent.child('gender').once('value').then((snapshot) => {
           console.log("Deleted a " + snapshot.val() + " member");
        });
    }
});

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