Firebase cloud functions, not working .forEach

Question

I am trying to call the .forEach function in my Cloud functions and it even works, but it does not return what I need, I am trying to get the branch key and it just returns TRUE.

I cannot remove return from the second line (I think this is a mistake), because as soon as I remove it, an error appears.

return admin.database().ref('test/100').once('value').then(function(snapshot) {
  return snapshot.forEach(function(childSnapshot) {
     var childKey = childSnapshot.key;
     return childKey;
  });
}).catch(function(error) {
  return 'error';
})

My databse:

"test" : {
  "100" : {
    "ineedthis" : {
      "example" : "example"
    },
  },
}

Return:

True

I will be very grateful to everyone who helps.

@mwilson I'm a beginner, I don't fully understand how to do it right in my case .. — Motivation10x, Aug 11 '20 at 15:00

score 1 · Answer 1 · answered Aug 11 '20 at 14:59

1

It looks like you're trying to use .forEach on an object. That will not work. It looks like you can just return snapshot.key directly:

return admin.database().ref('test/100').once('value').then(function(snapshot) {
  return snapshot.key)); // or snapshot.ineedthis
}).catch(function(error) {
  return 'error';
})

answered Aug 11 '20 at 14:59

mwilson

12,295
7
55
95

And if there are 2 branches, how can I get the key of two branches? – Motivation10x Aug 11 '20 at 15:03
I do not fully understand how everything works here, but I will definitely mark everything that is possible if you help me – Motivation10x Aug 11 '20 at 15:10

score 0 · Answer 2 · answered Aug 11 '20 at 15:03

0

According to the docs, snapshot.forEach returns a boolean, so it doesn't work like your typical js array iterator (which returns undefined).

What error is forcing you to return on the second line? And can you fix it by returning null after the iterator like this?

return admin.database().ref('test/100').once('value').then(function(snapshot) {
     snapshot.forEach(function(childSnapshot) {
         var childKey = childSnapshot.key;
         return childKey;
      });
      return null;
}).catch(function(error) {
  return 'error';
})

I wish I could comment, because mwilson is incorrect. The forEach function exists on the DataSnapshot object in this case. Hopefully you see this before marking that answer as correct.

answered Aug 11 '20 at 15:03

rmccreary

76
6

Null is returned – Motivation10x Aug 11 '20 at 15:08
That would indicate that snapshot has no keys to iterate through. Could you try using `getValue()` instead of `once('value')` – rmccreary Aug 11 '20 at 15:25
Nevermind sorry, I don't think that will work. Have you read through this in the docs? https://firebase.google.com/docs/database/admin/retrieve-data – rmccreary Aug 11 '20 at 15:43

Firebase cloud functions, not working .forEach

2 Answers2