Type 'List<dynamic>' is not a subtype of type 'List<String> in flutter

Question

when I fetch data from firebase

I got these errors like

why list dynamic could change into String type ?

type 'List<dynamic>' is not a subtype of type 'List<String>

I put the code below it. the loaded product does not contain items

Future<void> fetchandSetProduct() async {
    final url =
        Uri.https('cakejaffna-default-rtdb.firebaseio.com', '/cakelist.json');

    try {
      final response = await http.get(url);
      print(response.statusCode);

      final extractData = json.decode(response.body) as Map<String, dynamic>;
      final List<Cake> loadedProduct = [];
      print(extractData);
      extractData.forEach((cakeId, cakeData) {
        loadedProduct.add(Cake(
            id: cakeId,
            imageUrl: cakeData['imageUrl'],
            title: cakeData['title'],
            hotelName: cakeData['hotelName'],
            rating: cakeData['rating'],
            ratecount: cakeData['ratecount'],
            amount: cakeData['amount'],
            details: cakeData['details'],
            categories: cakeData['categories']));
      });
      _cakeList = loadedProduct ;
      notifyListeners();
    } catch (error) {
      print(error);
      print("relly error");
    }
  }

post the stacktrace you got during the exception

pskink
– pskink

2021-08-22 05:26:57 +00:00
Commented Aug 22, 2021 at 5:26 — pskink
– pskink, Commented Aug 22, 2021 at 5:26
can you post the response json?

Nidheesh MT
– Nidheesh MT

2021-08-22 08:00:52 +00:00
Commented Aug 22, 2021 at 8:00 — Nidheesh MT
– Nidheesh MT, Commented Aug 22, 2021 at 8:00

Pradeep Tintali · Accepted Answer · 2021-08-22 05:31:29Z

1

I think in your Cake model class categories is List<String> changing it to List<dynamic> should fix the problem.

answered Aug 22, 2021 at 5:31

Pradeep Tintali

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Comments

Bola Gadalla · Accepted Answer · 2022-05-10 20:50:14Z

1

Am assuming cakeData['categories'] is a list of categories? then you would do this

(cakeData['categories'].map((e) => e.toString())).toList()

Please note the parenthesis, they are important since you're converting the map to a list so you have to wrap the map with those parenthesis like this (map).toList();

And then you simply do this to each data point where you know it will be a list, of course you return any object if needed, in this case am returning a String. Simply trying to cast it to a list of strings List<String> will not work in this case.

answered May 10, 2022 at 20:50

Bola Gadalla

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Mohammad Shamsi · Accepted Answer · 2021-08-22 06:22:48Z

0

you can use as for type.

for Example :

 extractData.forEach((cakeId, cakeData) {
        loadedProduct.add(Cake(
            id: cakeId as int,
            imageUrl: cakeData['imageUrl'] as String,
            title: cakeData['title'] as String,
            hotelName: cakeData['hotelName'] as String,
            rating: cakeData['rating'] as double,
            ratecount: cakeData['ratecount'] as int,
            amount: cakeData['amount'] as int,
            details: cakeData['details'] as list<String>,
            categories: cakeData['categories'] as String));
      });

answered Aug 22, 2021 at 6:22

Mohammad Shamsi

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