CODEWITHSUNDEEP
javascriptfirebasegoogle-cloud-firestore
Ameen Izhac
Ameen Izhac

Reputation: 115

How can I make it so that this console.log is executed after the function above it has completed?

I am using firebase and I have run into an issue. What I am trying to do is allow a user to sign up, but to check the account doesn't already exist, I want to retrieve all of the usernames from firestore and then search through them to see if their proposed username already exists. Here is my code to do this:

document.querySelector("#form1").addEventListener("submit", e => {
    e.preventDefault();
    var users;
    firestore.collection("users").get().then(querySnapshot => {
        users = querySnapshot.docs.map(doc => doc.data());
        console.log(users);
    });
    console.log(users);
});

So I know that when I try to do console.log(users) for the second time, the function above may not have completed its execution which is why when I log it to the console I see "undefined". How can I change my code so that the second console.log(users) waits for the function above to complete?

I tried looking into this and found some stuff to do with "async" and "wait" but I couldn't figure out how to make these work in my code. Maybe that could be the solution?

Upvotes: 0

Views: 66

Answers (1)

Tarik Huber
Tarik Huber

Reputation: 7388

I can't warn you enough to not get all users to check if one of them has the same username. I can strongly recommend to query for a single user with the same username:

document.querySelector("#form1").addEventListener("submit", async (e) => {
  e.preventDefault();

  const theEnteredUsername = ""; // get it from somewhere

  // Create a reference to the cities collection
  var ref = firestore.collection("users");

  // Create a query against the collection.
  var query = await ref.where("username", "==", theEnteredUsername).get();

  if (query.empty) {
    //you can use the username
  } else {
    //username taken!!!
  }
});

Othervise your Firebase bill would be grow extremely with the increase of users in your app.

Upvotes: 1

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