Q: Read data from Cloud firestore with Firebase cloud function Firebase cloud function, when i am trying to fetch data and assigning to array, it says

TypeError: snapshot.forEach is not a function

Could you please help me to sort this out. I don't know what's wrong with this.
let userTokenList = [];
db.collection("UserTokens").doc(UserId).get().then(snapshot => {
    snapshot.forEach(doc => {
        var newelement = {
            "Token": doc.data().Token,
        }
        console.log(newelement);
        userTokenList = userTokenList.concat(newelement);
    });
});


A: You're getting a single document, so the result in your snapshot variable is a DocumentSnapshot and that doesn't have a forEach method.

If you want to get a single document, ditch the forEach loop and do:
db.collection("UserTokens").doc(UserId).get().then(doc => {
    var newelement = {
        "Token": doc.data().Token,
    }
    console.log(newelement);
    userTokenList = userTokenList.concat(newelement);
});


If you want to get all documents in the collection, do:
db.collection("UserTokens").get().then(snapshot => {
    snapshot.forEach(doc => {
        var newelement = {
            "Token": doc.data().Token,
        }
        console.log(newelement);
        userTokenList = userTokenList.concat(newelement);
    });
});

