Firebase - Queries

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Firebase offers various ways of ordering data. In this chapter, we will show simple query examples. We will use the same data from our previous chapters.

Order by Child

To order data by name, we can use the following code.

Example

Let us consider the following example.

var playersRef = firebase.database().ref("players/");

playersRef.orderByChild("name").on("child_added", function(data) {
   console.log(data.val().name);
});

We will see names in the alphabetic order.

Order by Key

We can order data by key in a similar fashion.

Example

Let us consider the following example.

var playersRef = firebase.database().ref("players/");

playersRef.orderByKey().on("child_added", function(data) {
   console.log(data.key);
});

The output will be as shown below.

Order by Value

We can also order data by value. Let us add the ratings collection in Firebase.

Now we can order data by value for each player.

Example

Let us consider the following example.

var ratingRef = firebase.database().ref("ratings/");

ratingRef.orderByValue().on("value", function(data) {
   
   data.forEach(function(data) {
      console.log("The " + data.key + " rating is " + data.val());
   });
   
});

The output will be as shown below.