CODEWITHSUNDEEP
javascriptfirebasefirebase-realtime-database
Caplin YT
Caplin YT

Reputation: 265

forEach method on Firebase invokes callback with child snapshot with undefined key

It's been a few months I started learning JavaScript, since I am an IOS developer, I prefer Firebase as my backend for my websites too.

So on today's practice, I used to read Firebase data and alert it to myself, I used this code,

Notice: those code's are only examples and used during my work, and it officially comes from Firebase's documentation.

var query = firebase.database().ref("users").orderByKey();

query.once("value")
  .then(function(snapshot) {
    snapshot.forEach(function(childSnapshot) {
      // key will be "ada" the first time and "alan" the second time
      var key = childSnapshot.key;
      // childData will be the actual contents of the child
      var childData = childSnapshot.val();

        alert(key); // also tried the (key.value); as well
  });

and here is my Firebase structure: Screenshot

and the output: Screenshot

Upvotes: 1

Views: 813

Answers (1)

Mike Axle
Mike Axle

Reputation: 1097

It's funny but firebase doesn't update their docs as often as their API changes, even worse if you're using Angular 4+. Try rewriting your code like this below. you need to return a boolean value after iterating a snapshot with forEach:

    var query = firebase.database().ref("users").orderByKey();
    query.once("value", (function(snapshot) {
        snapshot.forEach(function(childSnapshot) {
          // key will be "ada" the first time and "alan" the second time
          var key = childSnapshot.key;
          // childData will be the actual contents of the child
          var childData = childSnapshot.val();

          alert(key); // also tried the (key.value); as well
          return true;

      })
)

Upvotes: 2

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