Flutter 無效值：有效值范圍為空：0

Question

我正在嘗試從 API 獲取數據並將數據存儲在列表中，以便我可以在我的代碼中使用該列表，但它給出了無效值錯誤：有效值范圍為空：0

下面是代碼

class Services {
  final String apiKey = '*Hidden*';
  static const int numberOfFood = 50;
  List<String> foodNameList = [];
  getRandomBreakfast() async {
    http.Response response = await http.get(
      Uri.parse(
          'https://api.spoonacular.com/recipes/random?apiKey=$apiKey&number=$numberOfFood&tags=breakfast?'),
    );
    dynamic foodData = response.body;
    Map data = json.decode(foodData);
    for (int i = 0; i < numberOfFood; i++) {
      String foodName = (data['recipes'][i]['title']);
      foodNameList.add(foodName);
    }
  }
}

我想在下面的 GridView builder 中使用它

GridView.builder(
                  itemCount: Services.numberOfFood,
                  gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
                    crossAxisCount: 2,
                    crossAxisSpacing: 10,
                    childAspectRatio: 0.7,
                  ),
                  itemBuilder: (context, index) {
                    return FoodContainer(
                        foodLabel: Services().foodNameList[index]);
                  },
                ),

Answer 1

也許你的數據是空的，試試這個：

for (int i = 0; i < numberOfFood; i++) {
  if ((data['recipes'] as List).isNotEmpty) {
    String foodName = (data['recipes'][i]['title']);
    foodNameList.add(foodName);
  } else {
    print('Empty')
  }
}