Firebase的云功能:如何获取event.data.ref.parent.child(&"xxx& quot").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:

I'm having a structure on Firebase like this:

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

在我的云函数中，我写道:

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");
    }
});

但是，它会在 event.data.ref.parent.child().val 上给出错误，请告知在这种情况下如何获取该值.谢谢！

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

推荐答案

DeltaSnapshot 仅适用于匹配的位置.树中或同级中较高的数据不可用.如果您的会员数据不是很大，以至于您担心要监听其中的任何更改，则可以执行以下操作:

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");
    }
});

您原来的方法也可以，但是需要获取性别数据:

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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