Trying to make this as general so it can help other people. This question is more me struggling with the concepts of promises.

So I have a function that returns the value of a boolean variable. My idea is to pull some data off of Firebase, and then I was looping through the values... to then set the variable to true if found.

The issue that I was running into was that the value would be returned regardless of if the ForEach loop and the query were plete. I attempted to use some sort of promise resolving (in the code snippit below) to return it properly

export function CheckIfFriendsPending(id2){
    var userID = getFirebase().auth().currentUser.uid
    var indicator = false

     var retri = function()
    {   
           getFirebase().database().ref('members/' + userID + '/PendingFR').once('value').then(function(snap) {
                    console.log("~~~~~~~~~~~~~~~~~~go")

                    //if(result.hasOwnProperty('install_type'))
                    snap.forEach(function(childSnapshot) {

                        var childObject = childSnapshot.val()
                        if(childObject.hasOwnProperty('From')){
                            alert("OKAY")
                            if(childObject.From == userID && childObject.To == id2){
                                indicator = true
                            } else if(childObject.From == id2 && childObject.To == userID){
                                indicator = true

                            }
                        }

                    });


                })                          
    } // end retri

    Promise.all(retri).then(function() {
        return indicator
    })
}

Anyone have any idea for how to approach this? I guess a summarized version question is how to create a promise within a function that already returns a promise (which I believe the firebase database querys do). I guess it would have to wait for "ForEach" loop to resolve pletely as well.

Trying to make this as general so it can help other people. This question is more me struggling with the concepts of promises.

So I have a function that returns the value of a boolean variable. My idea is to pull some data off of Firebase, and then I was looping through the values... to then set the variable to true if found.

The issue that I was running into was that the value would be returned regardless of if the ForEach loop and the query were plete. I attempted to use some sort of promise resolving (in the code snippit below) to return it properly

export function CheckIfFriendsPending(id2){
    var userID = getFirebase().auth().currentUser.uid
    var indicator = false

     var retri = function()
    {   
           getFirebase().database().ref('members/' + userID + '/PendingFR').once('value').then(function(snap) {
                    console.log("~~~~~~~~~~~~~~~~~~go")

                    //if(result.hasOwnProperty('install_type'))
                    snap.forEach(function(childSnapshot) {

                        var childObject = childSnapshot.val()
                        if(childObject.hasOwnProperty('From')){
                            alert("OKAY")
                            if(childObject.From == userID && childObject.To == id2){
                                indicator = true
                            } else if(childObject.From == id2 && childObject.To == userID){
                                indicator = true

                            }
                        }

                    });


                })                          
    } // end retri

    Promise.all(retri).then(function() {
        return indicator
    })
}

Anyone have any idea for how to approach this? I guess a summarized version question is how to create a promise within a function that already returns a promise (which I believe the firebase database querys do). I guess it would have to wait for "ForEach" loop to resolve pletely as well.

• javascript
• firebase
• promise
• firebase-realtime-database

1 Answer 1

I think CheckIfFriendsPending should return a Promise:

export function CheckIfFriendsPending(id2) {
  return new Promise(function (resolve, reject) {
    var userID = getFirebase().auth().currentUser.uid;
    var indicator = false;
    getFirebase().database().ref('members/' + userID + '/PendingFR').once('value')
      .then(function (snap) {
        function userMatch(user) {
          if (!!user.From && user.From === userID && (user.To === id2 || user.To === userID)) {
            return resolve();
          }
        }
        snap.forEach(function (childSnapshot) {
          var childObject = childSnapshot.val();
          userMatch(childObject);
        });
        return reject();
      });
  });
}

Then you can call:

CheckIfFriendsPending(id2)
  .then(function() { console.log('Yes'); })
  .catch(function() { console.log('No'); });

Here's a simple working example.