CODEWITHSUNDEEP
listhttpflutterdart
Vincenzo
Vincenzo

Reputation: 6358

NoSuchMethodError: The method 'add' was called on null when adding a value to a list Flutter

I'm getting values from an API request, and store them into String variables to be added to a List<String>. When printing this variables prints are fine, but then I get NoSuchMethodError: The method 'add' was called on null. when adding them to the list. Does it mean that I'm not really converting them into strings? Can you spot what I'm doing wrong ?

As always many thanks for your time and help.

This is the method:

Future<List<String>> getCityDb(String isoLocationDb) async {
    print('getCityDb called');

    // namePrefix
    final String request =
        'https://wft-geo-db.p.rapidapi.com/v1/geo/cities?namePrefix=bologna&languageCode=IT'; //&types=ADM2'; // working

    var response = await get(Uri.encodeFull(request), headers: {
      'x-rapidapi-host': 'wft-geo-db.p.rapidapi.com',
      'x-rapidapi-key': apiKey,
    });

    if (response.statusCode == 200) {    
      var jsonResponse = convert.jsonDecode(response.body);
      List<dynamic> properties = jsonResponse['data'];
      print('properties are $properties');

      String name = properties.first['name'].toString();
      String region = properties.first['region'].toString();
      String country = properties.first['country'].toString();

//      print(' getCityDb ${jsonResponse.runtimeType} : $jsonResponse');
      print('getCityDb jsonResponse name is :$name');
      print('getCityDb jsonResponse region is :$region');
      print('getCityDb jsonResponse country is: $country');

      List<String> cityDb;
      cityDb.add(name);
      cityDb.add(region);
      cityDb.add(country);
      return cityDb;
    } else {
      print('getCityDB() Request failed with status: ${response.statusCode}.');
    }
  }

And this is the console print:

flutter: getCityDb called
flutter: properties are [{id: 148826, wikiDataId: Q1891, type: CITY, city: Bologna, name: Bologna, country: Italia, countryCode: IT, region: Emilia-Romagna, regionCode: 45, latitude: 44.493888888, longitude: 11.342777777}, {id: 3029926, wikiDataId: Q18488439, type: CITY, city: Bolognana, name: Bolognana, country: Italia, countryCode: IT, region: Toscana, regionCode: 52, latitude: 44.04018, longitude: 10.47244}, {id: 63950, wikiDataId: Q50839, type: CITY, city: Bolognano, name: Bolognano, country: Italia, countryCode: IT, region: Abruzzo, regionCode: 65, latitude: 42.216666666, longitude: 13.966666666}, {id: 66955, wikiDataId: Q18478734, type: CITY, city: Bolognano-Vignole, name: Bolognano-Vignole, country: Italia, countryCode: IT, region: Trentino-Alto Adige, regionCode: 32, latitude: 45.91196, longitude: 10.90497}]
flutter: getCityDb jsonResponse name is :Bologna
flutter: getCityDb jsonResponse region is :Emilia-Romagna
flutter: getCityDb jsonResponse country is: Italia
flutter: Erros is NoSuchMethodError: The method 'add' was called on null.

Upvotes: 1

Views: 87

Answers (3)

Manpreet Singh Pandher
Manpreet Singh Pandher

Reputation: 257

firstly, here you need to initialize list and then add value , try like this:-

List<String> cityDb=List();
cityDb.add(name);
cityDb.add(region);
cityDb.add(country);

Upvotes: 2

Muldec
Muldec

Reputation: 4901

The error message gives you exactly what's wrong : the add method was called on null.

You call the add method on cityDb, which means that cityDb is null.

Change this :

List<String> cityDb = new List<String>();

Upvotes: 2

Naeem
Naeem

Reputation: 514

initialize your List first.

List<String> cityDb = new List<String>();

Upvotes: 3

Related Questions