Firebase realtime database retrieve keys only

Question

I have this collection in firebase realtime database:

students:

{
  "Mike": {
    "Time 2022-08-22 09:04:57": {
      "Courses": [
        "Maths",
        "Chemistry",
        "Science"
      ]
    },
    "Time 2022-08-15 09:05:58": {
      "Courses": [
        "Physics",
        "Geography",
        "Literature"
      ]
    },
    "Time 2022-08-15 09:06:59": {
      "Courses": [
        "Computer Science",
        "Biology",
        "Chemistry"
      ]
    }
  },
  "John": {
    "Time 2022-08-22 10:04:57": {
      "Courses": [
        "Maths",
        "Chemistry",
        "Science"
      ]
    },
    "Time 2022-08-15 10:05:58": {
      "Courses": [
        "Physics",
        "Geography",
        "Literature"
      ]
    },
    "Time 2022-08-15 10:06:59": {
      "Data": [
        "Computer Science",
        "Biology",
        "Chemistry"
      ]
    },
    "Time 2022-08-15 10:07:59": {
      "Courses": [
        "Computer Science",
        "Biology",
        "Physics"
      ]
    }
  },
  "Steve": {
    "Time 2022-08-22 11:01:57": {
      "Courses": [
        "Maths",
        "Chemistry",
        "Science"
      ]
    }
  }
}

Now here I want to get the name of students only instead of retrieving complete object data.

Expected Response:

["Mike", "John", "Steve"]

What I tried so far is:

<script src="https://www.gstatic.com/firebasejs/3.2.0/firebase.js"></script>
<script>
var config = {};

firebase.initializeApp(config);

var records = [];

var ref = firebase.database().ref("students")

ref.on('value', function(snapshot) {
    
    var records = snapshot.val();
    
    for(var key in records) {

        records.push({
            user: key
        });             
    }    
});
</script>

In my case it provides the correct response but with basd approach, currently it is traversing all the data.

I need firebase to give me names of users only.

score 0 · Answer 1 · answered Aug 22 '22 at 13:35

0

To get only the keys into your array:

ref.on('value', function(snapshot) {
    var records = [];
    snapshot.forEach((child) => {
        records.push(child.key);
    }
    console.log(records);
});

answered Aug 22 '22 at 13:35

Frank van Puffelen

565,676
79
828
807

It will not process or query the whole documents from database right? – StormTrooper Aug 22 '22 at 13:38
since I have so many nested entries against these users, I dont want all that data to be retrieved from database – StormTrooper Aug 22 '22 at 13:40
I just tested your code, it is same as mine. no difference – StormTrooper Aug 22 '22 at 13:47
Oh yeah, both retrieve all data. There is no way to download only the keys from the Firebase Realtime Database through its SDKs. If you want to only get the names, consider storing exactly that: an additional node with just the names. – Frank van Puffelen Aug 22 '22 at 14:12

Firebase realtime database retrieve keys only

1 Answers1