Firestore WEB 触发事件

Question

I'm running my db to verify if "id" is already in use, if not, i can do my register, else, i cant user this id and i have to try another.

code:

db.collection("places").get().then(function (querySnapshot) {
querySnapshot.forEach(function (doc) {
    // console.log(doc.id)
    db.collection("places").doc(doc.id).collection("Local").where("id", "==", id_user)
        .get()
        .then(function (querySnapshot) {
            querySnapshot.forEach(function (doc2) {
                //cpnj is already registred
                if (doc2.exists) {
                    console.log("id already exist")
                    document.getElementById("preloader").style.display = "none";
                    alert("id in use, try another id");
                } else{
                    //register the user
                }
            });
        })
        .catch(function (error) {
            console.log("Error getting documents: ", error);
        });
    });
});

The problem is when id doesn't exist, the "else" inside the function is not "actived" because the Firebase condition".where("id", "==", id_user)" doesn't exist, so the query is not done.

How can i trigger this and after check that the "id" is not in use and proceed with registration?

Answer 1

Within a loop over a query snapshot, the document will always exist. If there are no results, the query snapshot will be empty and it'll right now simply not enter your forEach loop.

What you're looking for is whether the query snapshot has any results, which you can do with:

if (querySnapshot.empty) {
    //register the user
} else{
    console.log("id already exist")
    document.getElementById("preloader").style.display = "none";
    alert("id in use, try another id");
}