Question

我想对实时数据库中我想要的字段求平均，然后将它们放在另一个节点上

exports.taverage = functions.database.ref('/User/tsetUser/monthQuit/{pushId}')
    .onCreate((snapshot, context) => {
        return admin.database().ref('/User/tsetUser/monthQuit/{pushId}/quitTime').once('value')
            .then(function(snapshot) {
                let sum=0;
                snapshot.forEach(child => {
                    sum = sum + child.val();
                })
                let avg = sum / snapshot.numChildren();

                return admin.database().ref('/User/tsetUser/inform/standardQuit').set(avg);
            });
    });

错误：Reference.set失败：第一个参数在属性enter image description here中包含NaN

Answer 1

我的理解是，.numChildren()实际上应该是in the documentation所述的.getChildrenCount()。

此外，考虑通过执行以下操作来修改代码以解决“被零除”的情况：

functions.database.ref('/User/tsetUser/monthQuit/{pushId}')
.onCreate((snapshot, context) => {
    return admin.database().ref('/User/tsetUser/monthQuit/{pushId}/quitTime').once('value')
    .then(function(snapshot) {

        /* Get children could via getChildrenCount() */
        let divisor = snapshot.getChildrenCount();

        /* Ensure divisor is greater than zero to avoid
        divide by zero case */
        if(divisor > 0) {

            let sum=0;

            snapshot.forEach(child => {
                sum = sum + child.val();
            })
            let avg = sum / divisor;

            return admin.database().ref('/User/tsetUser/inform/standardQuit').set(avg);
        }

    });
});

获得火基函数的平均值，找到所需节点的平均值

1 个答案: