在运行嵌套查询的嵌套对象上使用firebase Cloud 函数搜索数据时未指定的索引

我正在使用fire-base来检索用户节点的嵌套数据，并且在运行查询时我面临这个问题从fire-base数据库中获取数据 .

考虑在/ users / YJdwgRO08nOmC5HdEokr1NqcATx1 / follow / users中将“.indexOn”：“userId”添加到您的安全规则中，以获得更好的性能 .

Database Structure:

"users" : {
    "1vWvSXDQITMmKdUIY7SYoLA1MgU2" : {
      "userEmail" : "test2kawee@gmail.com",
      "userId" : "1vWvSXDQITMmKdUIY7SYoLA1MgU2",
      "userName" : "Malik Abdul Kawee",
      "userPhoneNumber" : "",
      "userProfileImage" : "https://pbs.twimg.com/profile_images/1018741325875867648/ZnKeUiOJ_400x400.jpg"
    },
    "YJdwgRO08nOmC5HdEokr1NqcATx1" : {
      "following" : {
        "1vWvSXDQITMmKdUIY7SYoLA1MgU2" : {
          "currentFollowingUserId" : "YJdwgRO08nOmC5HdEokr1NqcATx1",
          "userEmail" : "test2kawee@gmail.com",
          "userId" : "1vWvSXDQITMmKdUIY7SYoLA1MgU2",
          "userName" : "Malik Abdul Kawee",
          "userPhoneNumber" : "",
          "userProfileImage" : "https://pbs.twimg.com/profile_images/1018741325875867648/ZnKeUiOJ_400x400.jpg"
        }
      },
      "userEmail" : "test2atif@gmail.com",
      "userId" : "YJdwgRO08nOmC5HdEokr1NqcATx1",
      "userName" : "Atif AbbAsi",
      "userPassword" : "test123",
      "userPhoneNumber" : "",
      "userProfileImage" : "http://paperlief.com/images/enrique-iglesias-body-workout-wallpaper-4.jpg"
    }
  }

Database Rules:

"users": {
     ".indexOn":  ["userId","currentFollowingUserId",".value"],
       "$userId": {
         "following": {
        //"$userId": {
             ".indexOn":  ["userId","currentFollowingUserId",".value"]
        }
    //}
       } 
}

Function Query:

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);


exports.sendFollowingNotifications = functions.database.ref('/users/{userId}/following/{followingId}')
       //.onWrite(event => {
         .onCreate((snap,context) => {  


        console.info("Child value is val() " ,snap);


        var childNodeValue=snap.val();

        var topic=childNodeValue.userId;

        //var ref = firebase.database().ref.child('users');

        //console.log("testing ref pathName : " ,snap.ref.parent.parent.parent.pathname);
    //  console.log("testing ref : " ,snap.ref.parent.parent.parent.path);

        //var ref = admin.database().ref("users");

        //.child('users')

        return snap.ref.parent.parent.parent.orderByChild("userId").equalTo(childNodeValue.currentFollowingUserId)

     // .on('child_changed').then(snapshot => { once('value')
         .once('value', function(snapshot){ 
        var parentNodeValue=snapshot.val();

        console.info("Topic ID " ,topic);

        console.info("Parent value is val() " ,snapshot.val());

              var payload = {
            data: {
                username: parentNodeValue.userName,
                imageurl:parentNodeValue.userProfileImage,
                description:"Started Following You"
            }
        };



           // Send a message to devices subscribed to the provided topic.
        return admin.messaging().sendToTopic(topic, payload)
            .then(function (response) {
                // See the MessagingTopicResponse reference documentation for the
                // contents of response.
                console.log("Successfully sent message:", response);
                return response;
            })
            .catch(function (error) {
                console.log("Error sending message:", error);
                return error;
            });

      });








      });

return snap.ref.parent.child（'users'） . orderByChild（“userId”） . equalTo（childNodeValue.currentFollowingUserId）

我认为问题出在这个查询上，我对下一个节点的第一个查询是返回数据但是当我检索其父节点用户的数据时，我收到警告 .

我尝试使用 functions.database.ref ，但它给了我以下异常 .

so I tried using this `snap.ref.parent.`to get reference of parent node.

Firebase函数，admin.database（） . ref（...）不是函数Firebase函数，functions.database（） . ref（...）不是函数