How to read List of Instance of '_JsonQuerySnapshot' in Flutter - flutter

Question

I am trying to read the data from a list that has the data of Instance of '_JsonQuerySnapshot'.
In the below code I am trying to get the data from DB
getData() async {
var db = FirebaseFirestore.instance;
var categoryList = [];
db.collection('categories')
.doc(value)
.get()
.then((DocumentSnapshot doc) {
var listSubCol = doc["categoryCollection"];
listSubCol.forEach((id) {
db.collection('categories')
.doc(value)
.collection(id)
.get()
.then((snapshot) {
categoryList.add(snapshot);
return categoryList;
});
});
});
}
Below is the code where I am printing the values.
FutureBuilder(
future: getData(),
builder: (BuildContext context, snapshot){
if (snapshot.hasError) {
return Text("Something went wrong");
}
if (snapshot.connectionState == ConnectionState.done) {
print('Data: ${snapshot.data}');
return Text("Text");
}
return Text("Text Outside");
}
)
I got a null value.
Can anyone please help me with how to get the data?

Answer 1

The getData is a Future<void>, so when the FutureBuilder is completed the snapshot.data is always null.
Change getData to return a List of whatever you are getting.
Future<List<Categories>> getData() async {
var db = FirebaseFirestore.instance;
final List<Categories> categoryList = [];
await db.collection('categories')
.doc(value)
.get()
.then((DocumentSnapshot doc) {
var listSubCol = doc["categoryCollection"];
listSubCol.forEach((id) {
db.collection('categories')
.doc(value)
.collection(id)
.get()
.then((snapshot) {
categoryList.add(snapshot);
return categoryList;
});
});
});
return categoryList;
}

Answer 2

getData() async {
var db = FirebaseFirestore.instance;
await db.collection('categories').doc(value).get().then((DocumentSnapshot doc) {
var listSubCol = doc["categoryCollection"];
listSubCol.forEach((id) {
db.collection('categories').doc(value).collection(id).get().then((snapshot) {
snapshot.docs.forEach((element) {
categoryList.add(element.data());
});
});
return categoryList;
});
});
return categoryList;
}
using the above method i got the data from Firestore.