Hello everyone!
I am trying to fetch my product Data from Firebase server ,when i sign in i got this error:
Unhandled Exception: NoSuchMethodError: The method ‘[]’ was called on null.
when I face this problem before i added these variable to the function below:
bool? _isFavorite =
favoriteData[key] != null || favoriteData[key] == 'true'
? true
: false;
but when i deleted favorite data from the server it gave me error again! it should take the "False"value when it null!
i think my error related to null safety but i cant fix it
i will share the Function which related to to this error and model and if there any solution I would be grateful for it ,Thank you!
Fetch Data Function:
Future<void> fetchAndSetProducts([bool filterByUser = false]) async {
final filterString =
filterByUser ? 'orderBy="creatorId"&equalTo="$userId"' : '';
var url =
'https://ecommerce-test-753ad-default-rtdb.firebaseio.com/products.json?auth=$authToken&$filterString';
try {
final response = await http.get(Uri.parse(url));
final extractedData = json.decode(response.body) as Map<String, dynamic>;
if (extractedData == {}) {
return;
}
url =
'https://ecommerce-test-753ad-default-rtdb.firebaseio.com/userFavorites/$userId.json?auth=$authToken';
final favoriteResponse = await http.get(Uri.parse(url));
final favoriteData = json.decode(favoriteResponse.body);
print(favoriteData);
print(extractedData);
final List<Product> loadedProduct = [];
extractedData.forEach((key, value) {
bool? _isFavorite =
favoriteData[key] != null || favoriteData[key] == 'true'
? true
: false;
loadedProduct.add(
Product(
id: key,
title: value['title'],
price: value['price'],
imageUrl: value['imageUrl'],
description: value['description'],
isFavorite: _isFavorite,
),
);
});
_productItems = loadedProduct;
notifyListeners();
} catch (e) {
rethrow;
}
}
product Model class:
class Product with ChangeNotifier {
final String id;
final String title;
final double price;
final String imageUrl;
final String description;
bool isFavorite;
Product({
required this.id,
required this.title,
required this.price,
required this.imageUrl,
required this.description,
this.isFavorite = false,
});
void _setFavValue(bool newValue) {
isFavorite = newValue;
notifyListeners();
}
Future<void> toggleFavoriteStatus(String authToken, String
userId) async {
final oldStatus = isFavorite;
isFavorite = !isFavorite;
notifyListeners();
final url =
'https://ecommerce-test-753ad-default-
rtdb.firebaseio.com/userFavorites/$userId/$id.json?
auth=$authToken';
try {
final response = await http.put(
Uri.parse(url),
body: json.encode(isFavorite),
);
if (response.statusCode >= 400) {
_setFavValue(oldStatus);
}
} catch (error) {
_setFavValue(oldStatus);
}
}
I also Added this line to Firebase rules:
"products":{
".indexOn":["creatorId"],
>Solution :
By checking favoriteData[key] for null is not enough, it is possible that favoriteData itself is null, try this:
bool? _isFavorite =
favoriteData != null && favoriteData[key] != null && favoriteData[key] == 'true'
? true
: false;