How to query the existing children and loop over an Object to detect if it exists in Firebase using a Google Cloud Function?

Question

I am trying to update (adding) some children on a firebase database. On this scenario I need to update a node without overwriting all the child nodes with Google Cloud Function

Answer 1

You could do as follow:

let afterIns;
exports.updateRoom = functions.database.ref('/doors/{MACaddress}').onWrite((change, context) => {

    const beforeData = change.before.val();  //data before
    const insBefore = beforeData.ins;

    const afterData = change.after.val(); // data after the write
    const roomPushKey = afterData.inRoom;
    afterIns = afterData.ins;

    return admin.database().ref().update(updates);

    const updates = {};

    Object.keys(ins).forEach(key => {
        if (insBefore.hasOwnProperty(key)) { // checking if the insBefore object has a key equal to value 'key'
            //True -> add an extra character at the existing key
            updates['/rooms/' + roomPushKey + '/ins/' + key + '_a'] = true;  //<- _a being the extra character
        } else {
            updates['/rooms/' + roomPushKey + '/ins/' + key] = true;
        }
    });

    return admin.database().ref().update(updates);

}).catch(error => {
    console.log(error);
    //+ other error treatment if necessary

});

Don't forget the function returns the data before change.before.val(); (in addition to the data after), therefore you don't have to do admin.database().ref().parentPath.on('value', function(snapshot) {

---

EDIT after comments

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

});