type 'Future<dynamic>' is not a subtype of type 'Stream<dynamic>' getting data from Firebase - flutter

Question

I'm retrieving data from Firebase Storage and Firestore, to show the items in a list with the icon (if the item is a file) or the image (if is image). The problem is, If I get all the images in one time it doesn't load all.. It loads at maximum 20 and crashes due to memory leaking. So My idea is to do a list which gets 10 elements by time, and when the user scroll down to the bottom of the results, it loads more 10 and subsequently. But, I was using Future builder and with it I cant update the list when I need and the problem continues, so now, I'm trying to get in a stream and show with a StreamBuilder to be able to update the list dynamically.
this is my controller:
loadList(String submenu, [int limit]) async {
var parts = submenu.split('/');
var pathSlashless = parts[0].trim();
var subPathSlashless = parts.sublist(1).join('/').trim();
var snapshot = await _storage.ref().child("/${submenu}");
var retorno = await snapshot.listAll();
List<ItemLab> conteudo = [];
if(subPathSlashless.isEmpty || subPathSlashless == null){
retorno.prefixes.forEach((element) {
conteudo.add(
ItemLab(
tipo: 'PASTA',
elemento: element,
),
);
});
}
for(int i = 0; i < retorno.items.length ; i++){
var url = await retorno.items[i].getDownloadURL();
conteudo.add(
ItemLab(
tipo: 'FILE',
elemento: retorno.items[i],
imageUrl: url,
),
);
if(limit != null){
if(conteudo.length > limit){
hasMore = true;
return Stream.value(conteudo);
}else{
hasMore = false;
print("less than 9");
}
}
}
try {
if(subPathSlashless.isNotEmpty){
print(subPathSlashless);
List items;
await databaseReference
.collection("lab_${pathSlashless}_url")
.snapshots().forEach((element) {
element.docs.forEach((f) {
if(f.data()['videos'] != null){
items == null ? items = f.data()['videos'] :
items.addAll(f.data()['videos']);
};
print("ITEMS :::: >>> ${items}");
});
});
for(int i = 0; i < items.length; i ++){
//print(items[i]);
conteudo.add(
ItemLab(
tipo: 'VIDEO',
elemento: null,
video: items[i],
),
);
}
}else{
await databaseReference
.collection("lab_${pathSlashless}_url")
.snapshots().forEach((element) {
element.docs.forEach((f) {
if(f.data().isNotEmpty){
print(f.data());
if(f.data().keys.contains("videos")){
conteudo.add(
ItemLab(
tipo: 'PASTA',
pastaVideo: findFolderName(f.reference.path)
),
);
}else{
conteudo.add(
ItemLab(
tipo: 'VIDEO',
elemento: null,
video: f.data(),
),
);
}
}
});
});
}
}catch(e){
print(e);
}
pathSlashless = null;
subPathSlashless = null;
conteudo = checkDuplicateFolder(conteudo, submenu);
return Stream.value(conteudo);
}
And here my list:
return StreamBuilder(
stream: ctrl.loadList(submenu),
builder: (ctx, snapshot) {
But, if I run this code it throws this error:
type 'Future' is not a subtype of type 'Stream'
How Can I handle that to be able to update the list dynamically using a stream instead of a Future

Answer 1

You can't await .snapshots(), as it returns stream, you can change it to get. Also learn more about flutter firebase realtime and normal use case, check the flutter fire docs
loadList(String submenu, [int limit]) async {
var parts = submenu.split('/');
var pathSlashless = parts[0].trim();
var subPathSlashless = parts.sublist(1).join('/').trim();
var snapshot = await _storage.ref().child("/${submenu}");
var retorno = await snapshot.listAll();
List<ItemLab> conteudo = [];
if(subPathSlashless.isEmpty || subPathSlashless == null){
retorno.prefixes.forEach((element) {
conteudo.add(
ItemLab(
tipo: 'PASTA',
elemento: element,
),
);
});
}
for(int i = 0; i < retorno.items.length ; i++){
var url = await retorno.items[i].getDownloadURL();
conteudo.add(
ItemLab(
tipo: 'FILE',
elemento: retorno.items[i],
imageUrl: url,
),
);
if(limit != null){
if(conteudo.length > limit){
hasMore = true;
return Stream.value(conteudo);
}else{
hasMore = false;
print("less than 9");
}
}
}
try {
if(subPathSlashless.isNotEmpty){
print(subPathSlashless);
List items;
(await databaseReference
.collection("lab_${pathSlashless}_url")
.get()).docs.forEach((f) {
if(f.data()['videos'] != null){
items == null ? items = f.data()['videos'] :
items.addAll(f.data()['videos']);
};
print("ITEMS :::: >>> ${items}");
});
for(int i = 0; i < items.length; i ++){
//print(items[i]);
conteudo.add(
ItemLab(
tipo: 'VIDEO',
elemento: null,
video: items[i],
),
);
}
}else{
(await databaseReference
.collection("lab_${pathSlashless}_url")
.get()).docs.forEach((f) {
if(f.data().isNotEmpty){
print(f.data());
if(f.data().keys.contains("videos")){
conteudo.add(
ItemLab(
tipo: 'PASTA',
pastaVideo: findFolderName(f.reference.path)
),
);
}else{
conteudo.add(
ItemLab(
tipo: 'VIDEO',
elemento: null,
video: f.data(),
),
);
}
}
});
}
}catch(e){
print(e);
}
pathSlashless = null;
subPathSlashless = null;
conteudo = checkDuplicateFolder(conteudo, submenu);
return conteudo;
}
And the list
return FutureBuilder(
future: ctrl.loadList(submenu),
builder: (ctx, snapshot) {