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Grrrrrag
Grrrrrag

Reputation: 47

Firebase return function after Snapshot function is finished

I want my function to return, after the ((querySnapshot) => {... function is finished. At the moment, my noOpponent function returns always false after calling, Thats probably because its returning, before the ((querySnapshot) => {... function is finished and so its returned, before the state is set true. I already tried to call the noOpponent function with var a = await noOpponent(key), but its not working, because as i already wrote, I think i have to await for the ((querySnapshot) => {... function. How can I do this?

export const noOpponent = (Key) => {
  var state = false;
  console.log("key: " + Key)
  duettsRef
    .where("key", "==", Key)
    .where("player1", "!=", firebase.auth().currentUser.uid)
    .where("player2", "==", "")
    .limit(1)
    .get()
    .then((querySnapshot) => {
     console.log("QuerysnapshotResult: " + !querySnapshot.empty);
     state = true;
      })
      return state;
};

Upvotes: 0

Views: 104

Answers (3)

Renaud Tarnec
Renaud Tarnec

Reputation: 83181

The other answers propose to use async/await, which is very good and recommended for code readability.

Let's show here how you should do if you still want to use then():

export const noOpponent = (Key) => {
  var state = false;
  console.log("key: " + Key)
  return duettsRef    // <=== See the return here. More at https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Using_promises#chaining 
    .where("key", "==", Key)
    .where("player1", "!=", firebase.auth().currentUser.uid)
    .where("player2", "==", "")
    .limit(1)
    .get()
    .then((querySnapshot) => {
       console.log("QuerysnapshotResult: " + !querySnapshot.empty);
       state = true;

       return state;   // See how we call return in the then block and not outside of it

    });
      
};

Note that the noOpponent() function is asynchronous and returns a Promise.

Upvotes: 2

Tarik Huber
Tarik Huber

Reputation: 7418

That is a perfect fit for async/await. It turns async code to something like sync code. You would need to write your code like this:

export const noOpponent = async (Key) => {
  var state = false;
  console.log("key: " + Key)
  const querySnapshot = await duettsRef
    .where("key", "==", Key)
    .where("player1", "!=", firebase.auth().currentUser.uid)
    .where("player2", "==", "")
    .limit(1)
    .get()
    
 console.log("QuerysnapshotResult: " + !querySnapshot.empty);
 state = true;
      
 return state;
};

Make sure when you call noOpponent to also use async or then.


noOpponent('key').then(state=>{
  console.log('state',state)
})

Upvotes: 1

Dipan Sharma
Dipan Sharma

Reputation: 1133

Try this code:

export const noOpponent = async (Key) => {
  var state = false;
  console.log("key: " + Key)
  let querySnapshot = await duettsRef
    .where("key", "==", Key)
    .where("player1", "!=", firebase.auth().currentUser.uid)
    .where("player2", "==", "")
    .limit(1)
    .get();
    
   // do something like assign value to state then return
      return state;
};

Upvotes: 1

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