React Native - How to deal with this - react-native

Question

I'm a beginner and don't know how to go about it. I have a "state" collection and a sub-collection "city". The city has a people field with the amount of people. How to download the number of people in a city and display it in the country view.
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const getData = () => {
firestore().collection('users').doc(user.uid).collection('country')
.onSnapshot(
 querySnapshot => {
const countryData = [];
let total = 0;
 querySnapshot.forEach(doc => {
countryData.push({...doc.data(), id: doc.id});
firestore()
.collection('users')
.doc(user.uid)
.collection('country')
.doc(doc.id)
.collection('city')
.onSnapshot(
 querySnapshot => {
const itemPeople = [];
let totalPeople = 0;
 querySnapshot.forEach(doc2 => {
totalPeople += doc2.data().people;
itemPeople.push({totalPeople});
});
setItemPeople(totalPeople);
    },
)
});
setCountryData(countryData);
    },
      error => {
       console.log(error)
    }
)
};
useEffect(() => {
getData();
}, []);

Answer 1

Here is the example how you can get the people value
const result = firebase
.firestore()
.collection("Country")
.doc("your user's UID")
.collection("City")
.get()
.then(querySnapshot => {
querySnapshot.forEach(queryDocumentSnapshot => {
console.log(queryDocumentSnapshot.get("People"));
});
})
.catch(err => {
alert(err);
});