如何解决如何通过在 Flutter 中以 JSON_Serializable 方式遍历 JSON 数组来填充 GridView?
我正在尝试解析一组 JSON 对象以填充 Flutter 中的 GridView。 到目前为止,我只能得到一个对象,但不能遍历整个对象数组。
JSON 字符串:A list of Beef recipe objects within 'beef' array.
我的代码:
import 'dart:convert';
import 'package:Flutter/material.dart';
import 'package:http/http.dart' as http;
class SpecificCategoryPage extends StatefulWidget {
late final String category;
SpecificCategoryPage({Key? key,required this.category}) : super(key: key);
@override
_SpecificCategoryPageState createState() => _SpecificCategoryPageState();
}
class _SpecificCategoryPageState extends State<SpecificCategoryPage> {
late Future<Meal> meals;
late List<Widget> mealCards;
@override
Widget build(BuildContext context) {
return Scaffold(
body: FutureBuilder<Meal>(
builder: (context,snapshot) {
if (snapshot.hasData) {
return Text(
'Truest\nId: ${snapshot.data!.id}. ${snapshot.data!.meal}');
} else {
return Text('${snapshot.error}');
}
// Be default,show a loading spinner.
return CircularProgressIndicator();
},future: meals,),);
}
@override
void initState() {
super.initState();
meals = _fetchMeals();
}
Future<Meal> _fetchMeals() async {
final http.Response mealsData = await http.get(
Uri.parse('https://www.themealdb.com/api/json/v1/1/filter.PHP?c=Beef'));
if (mealsData.statusCode == 200)
return Meal.fromJson(jsonDecode(mealsData.body));
else
throw Exception('Failed to load meals');
}
class Meal {
final String? id,meal;
Meal({required this.id,required this.meal});
factory Meal.fromJson(Map<String,dynamic> json) {
return Meal(
id: json['meals'][0]['idMeal'],meal: json['meals'][0]['strMeal']);
}
}
示例对象遍历路径:
{"meals":[{"strMeal":"Beef and Mustard Pie","strMealThumb":"https:\/\/www.themealdb.com\/images\/media\/meals\/sytuqu1511553755.jpg","idMeal":"52874"},{object1},{object2}]}
我得到了什么:
{"strMeal":"牛肉和芥末 Pie","strMealThumb":"https://www.themealdb.com/images/media/meals/sytuqu1511553755.jpg","idMeal":"52874"}
如何获取数组中的所有对象并扩充 GridView 小部件?
解决方法
import 'dart:convert';
// First you should create a model to represent a meal
class Meal {
// Place all the meal properties here
final String strMeal;
final String strMealThumb;
final String idMeal;
// Create a constructor that accepts all properties. They can be required or not
Meal({
required this.strMeal,required this.strMealThumb,required this.idMeal,});
// Create a method (or factory constructor to populate the object based on a json input)
factory Meal.fromJson(Map<String,dynamic> json) => Meal(
strMeal: json['strMeal'],strMealThumb: json['strMealThumb'],idMeal: json['idMeal'],);
String toString() {
return 'strMeal: $strMeal,strMealThumb: $strMealThumb,idMeal: $idMeal';
}
}
/// Then you should create another object to represent your response
/// It holds a list of meals that'll be populated by your API response
class YourAPIResponse {
final List<Meal> meals;
YourAPIResponse({required this.meals});
factory YourAPIResponse.fromJson(Map<String,dynamic> json) =>
YourAPIResponse(
meals: List<Meal>.from(
json['meals'].map((meal) => Meal.fromJson(meal)),),);
}
void main() {
// Test data: This will be your API response
String jsonString = '{"meals": [{"strMeal": "Beef and Mustard Pie","strMealThumb": "https://www.themealdb.com/images/media/meals/sytuqu1511553755.jpg","idMeal": "52874"}]}';
final apiResponse = YourAPIResponse.fromJson(json.decode(jsonString));
// Your meals list
// You can use this to populate the gridview
print(apiResponse.meals);
}
,
尝试类似:
...
return jsonDecode(mealsData.body)['meals'].map((meal) => Meal.fromJson(meal)).toList();
...
class Meal {
final String? id,meal;
Meal({required this.id,required this.meal});
factory Meal.fromJson(Map<String,dynamic> json) {
return Meal(
id: json['idMeal'],meal: json['strMeal']);
}
}
这会迭代响应正文中的膳食并将它们映射到 Meal
列表。
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