Get value from Firebase using javascript

Question

I tried to retrieve data with the following manner but it didn't work: Unhandled Rejection (TypeError): snapshot.val is not a function. (In 'snapshot.val()', 'snapshot.val' is undefined)

var companyScore, userScore;

            firebaseApp.firestore().collection('JobPosting')
            .doc(postId).get().then(snapshot => {
                console.log("Snapshot");
                console.log(snapshot);
                companyScore = snapshot.val().score;
              });
            firebaseApp.firestore().collection('people')
            .doc(currentUser.uid).get().then(snapshot => {
                userScore = snapshot.val().score;
              });

I guess I need a solution to get the snapshot data (supposedly a json or hash table), so that I can get the value under the index of score.

Pranav · Accepted Answer · 2021-06-29 04:47:33Z

2

You should use .data() and not .val()

Therefore, the updated code will be like this:

var companyScore, userScore;

            firebaseApp.firestore().collection('JobPosting')
            .doc(postId).get().then(snapshot => {
                console.log("Snapshot");
                console.log(snapshot);
                companyScore = snapshot.data().score;
              });
            firebaseApp.firestore().collection('people')
            .doc(currentUser.uid).get().then(snapshot => {
                userScore = snapshot.data().score;
              });

Link to the official docs: https://firebase.google.com/docs/firestore/query-data/get-data#get_a_document

answered Jun 29, 2021 at 4:47

Pranav

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4 Comments

Memphis Meng Over a year ago

It worked partly, but I met a new issue: snapshot.data().score or snapshot.data()['score'] doesn't retrieve anything but NaN, though my firebase has already had the key score.

Pranav Over a year ago

Try console.loging the data and see what are you getting

Memphis Meng Over a year ago

My fault there, buddy. I figured out that it's because of the asynchronized nature of firebase. thanks!

Pranav Over a year ago

You're welcome buddy! Sometimes mistakes happen. I think you should go through the example codes given in the docs to refresh your knowledge about using the SDK.

Dharmaraj · Accepted Answer · 2021-06-29 05:52:07Z

0

Getting a document from Firestore returns a DocumentSnapshot which does not have a .val() method on it. (That method exists on Realtime Database's DataSnapshot).

Try refactoring your code to:

firebaseApp.firestore().collection('JobPosting').doc(postId).get().then(snapshot => {
  console.log("Snapshot", snapshot);
  companyScore = snapshot.data().score;
});

The data method:

Retrieves all fields in the document as an Object. Returns 'undefined' if the document doesn't exist.

answered Jun 29, 2021 at 5:52

Dharmaraj

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