CODEWITHSUNDEEP
node.jsfirebasefirebase-realtime-database
Lion Smith
Lion Smith

Reputation: 655

UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: Can't set headers after they are sent

so im currently testing my query where specific data will be fetched if it matches the required parameters.

router.get('/getNewWatch/:sdate/:shft/:type', function(req, res){
    reqDate = req.params.sdate;
    reqShift = req.params.shft;
    reqType = req.params.type;

    var watcher = database.ref('watch');

    watcher.once('value', function(snapshot){
        var promises = [];

        snapshot.forEach(function(childSnapshot){
            promises.push(new Promise((resolve, reject) =>{
                resolve({
                    childKey: childSnapshot.key,
                    childData: childSnapshot.val()

                });
            }));
        });
        Promise.all(promises).then(function(snapshot){
            var dataSet = [];

            snapshot.forEach(function(result){
                if(result.childData.availability != 'undefined'){
                    if(result.childData.availability[reqDate]){
                        res.send('yes we have');
                    }else{
                        res.send('no we dont');
                    }
                }else{
                    res.send('no available watchers');
                }
            });
            res.json(dataSet);
        })

    });
});

1st is im trying to filter if child available exist on my data. then next is to filter if date matched the requiredDate. my data looks like this

watch
| --- 12i3g1uy2g412u
        | ----available
                | -----2018-02-01
                          |----isGood: "true"
                          |----shft: "Night"
| --- jh2g53hjg535hg
| --- 7i8hi79u89hui5
        | ----available
                | -----218-02-02
                          |----isGood:"false"
                          |----shft:"Day"

the response is good i got the correct response based on condition but my problem is when it returns the reponse it also return this error on my console.. UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: Can't set headers after they are sent.

UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): TypeError: Cannot read property '2018-02-07' of undefined

Upvotes: 0

Views: 1542

Answers (1)

Rahul Sharma
Rahul Sharma

Reputation: 10111

Try this 

router.get('/getNewWatch/:sdate/:shft/:type', function (req, res) {
    reqDate = req.params.sdate;
    reqShift = req.params.shft;
    reqType = req.params.type;

    var watcher = database.ref('watch');

    watcher.once('value', function (snapshot) {
        var promises = [];

        snapshot.forEach(function (childSnapshot) {
            promises.push(new Promise((resolve, reject) => {
                resolve({
                    childKey: childSnapshot.key,
                    childData: childSnapshot.val()

                });
            }));
        });
        Promise.all(promises).then(function (snapshot) {
            var dataSet = {};

            snapshot.forEach(function (result, index) {
                if (result.childData.availability) {
                    if (result.childData.availability[reqDate]) {
                        dataSet['childData-' + index] = 'yes we have'; // instead of 'childData-'+index you can give user friendly key.
                    } else {
                        dataSet['childData-' + index] = 'no we dont';
                    }
                } else {
                    dataSet['childData-' + index] = 'no available watchers';
                }
            });
            res.json(dataSet);
        })
    });
});

Output will be something like:

{
    "childData-1": "yes we have",
    "childData-2": "no we dont",
    "childData-3": "no available watchers",
}

Upvotes: 1

Related Questions