Retrieving only the parent elements from firebase : Angularfire

Question

The image shows the structure of my database. I want to print 1, 2 ... (so on) i.e. the parent element names alone. But couldn't understand how to do that.

Answer 1

The Firebase Database is essentially one JSON object.

This object is in a tree structure. If you read from one location in the tree, you'll get each piece of data underneath it.

Take a look at this sample database.

{
  "items": {
    "1": {
      "title": "Hi"
    },
    "2": {
      "title": "Bye"
    }
  }
}

There is no way with the JavaScript SDK or AngularFire, to only read the parent keys of 1 and 2 under "items".

If you only want to read the parent keys, you'll need to create an index for them in the Firebase database.

{
  "items": {
    "1": {
      "title": "Hi"
    },
    "2": {
      "title": "Bye"
    }
  },
  "itemKeys": {
    "1": "Hi",
    "2": "Bye"
  }
}

Now you can create a reference at the itemKeys location and pass that to a $firebaseArray() or $firebaseObject().

var ref = new Firebase('<my-firebase-app>.firebaseio.com/itemKeys');
var syncArray = $firebaseArray(ref);

If you're concerned with keeping two separate data structures consistent, check out the client-side fan-out feature.