How To Query The Existing Children Of A Sibling Node And Loop Over Them To Detect If It Exists?

I am trying to update (adding) new children on a firebase database. On this scenario I am updating two nodes and_'door/{MACaddress_1}/ins'_ & _'doors/{MACaddress_2}/ins'_ and b

Solution 1:

This question originated two different approaches. Please find them here:

1) By Renaud Tarnec using the Cloud Function

This should work, but I haven't test it. You may need to test is insBefore is undefined in addition to testing it is null. I let you fine tune it.

let insAfter;
let roomPushKey ;
exports.updateRoomIns = functions.database.ref('/doors/{MACaddress}').onWrite((change, context) => {
    const afterData = change.after.val(); // data after the write
    roomPushKey = afterData.inRoom;
    insAfter = afterData.ins;
    return admin.database().ref('/rooms/' + roomPushKey).once('value').then(snapshot => {
    const insBefore = snapshot.val().ins;
    const updates = {};
    if (insBefore === null || insBefore === undefined ) {
        Object.keys(insAfter).forEach(key => {
           updates['/rooms/' + roomPushKey + '/ins/' + key] = true;
        });
    } else {
        Object.keys(insAfter).forEach(key => {
           if (insBefore.hasOwnProperty(key)) {
              updates['/rooms/' + roomPushKey + '/ins/' + key + '_a'] = true; 
           } else {
              updates['/rooms/' + roomPushKey + '/ins/' + key] = true;
           }
        });
    }
    return admin.database().ref().update(updates);
    });
});.catch(error => {
    console.log(error);
    //+ other error treatment if necessary

});

2) the second approach was a more direct one

I have decided to solve it on the Arduino program, because all doors have different MAC Addresses I simply added the MAC address to the end of of the timestamp and because no door will register two ins at the same time that did the trick for me.