orders the objects received from firebase in an array - firebase

Question

I am developing an application with React-native and I am using firebase in the backend. the problem is that I am not able to recover the elements of my Realtime database in order of arriving. each time I launch my application the order of loading data is always different. I have thought of implementing the sorted quick to try to sort the object array received from firebase before display in my app but I received this error code: '' TypeError: undefined is not an object (evaluating 'array.length') ''. here is the code recovery of firebase objects
`import database from
'# react-native-firebase / database';
export const getAllPublications = async () => {
let list = [];
await database ()
.ref ('/ publications')
.once ('value')
.then (snapshot => {
for (const pub in snapshot.val ()) {
if (snapshot.val (). hasOwnProperty (pub)) {
const element = snapshot.val () [pub];
if (element) {
list.push ({id: pub, ... element});
}
}
}
});
return list;
} `
here my function to try to sort the table received from firebase
`export const quickSort = (array) => {
if (array.length <2) {
return array;
}
var pivot = array [0];
var lesserArray = [];
var greaterArray = [];
var date1 = new Date (pivot.timeago);
for (var i = 1; i <array.length; i ++) {
var date2 = new Date (array [i] .timeago);
if (date2.getTime ()> = date1.getTime ()) {
greaterArray.push (array [i]);
} else {
lesserArray.push (array [i]);
}
}
return quicksort (greaterArray) .concat (pivot, quicksort (lesserArray));
} `
after having received the elements of the base here is how I tried to sort them before having the error:TypeError: undefined is not an object (evaluating 'array.length')
const [publications, setPublications] = useState([]);
useEffect(() => {
getAllPublications()
.then((pubs) => {
setPublications(pubs);
setPublications(quicksort(publications));
setLoading(false);
})
}
here is an image of how my database is structured :
click here to see image

Answer 1

If transforming objects to arrays is something you do often when querying Firebase, you can make a short util function.
So you could do something like:
const transformFirebaseSnapshot = snapshot =>
Object.entries(snapshot.val())
.map(([id, fields]) => ({ id, ...fields }));
And use it as follows:
const getAllPublications = () => database()
.ref('/publications')
.once('value')
.then(transformFirebaseSnapshot);
Finally, put the pieces together:
const [publications, setPublications] = useState([]);
useEffect(() => {
getAllPublications()
.then(pubs => {
setPublications(quicksort(pubs));
setLoading(false);
});
}, []);
Give that a try and see if anything changes.
Good luck ;)