我正在嘗試在 Flutter 中創建 API 請求，但我收到以下錯誤作為回應
“List”型別不是“Map<String, dynamic>”型別的子型別
我正在嘗試創建第一個 API，請讓我知道該方法是否正確，這是我的代碼：
Future<Welcome> fetchProduct() async {
final response = await http.get(Uri.parse(
'https://api.azabazar.com/api/all-products/?fbclid=IwAR0v4BAB_gFTcpU7Jjqg_t0MnUkUxq8sWPgLj1BHrmOOq_Nd132mz9F8iSU'));
if (response.statusCode == 200) {
// If the server did return a 200 OK response,
// then parse the JSON.
return Welcome.fromJson(jsonDecode(response.body));
} else {
// If the server did not return a 200 OK response,
// then throw an exception.
throw Exception('Failed to load album');
}
}
班級模型：
class Welcome {
final String title;
final DateTime date;
final String image;
final String description;
final int category;
final int price;
Welcome({
required this.title,
required this.date,
required this.image,
required this.description,
required this.category,
required this.price,
});
factory Welcome.fromJson(Map<String, dynamic> json) {
return Welcome(
title: json["title"],
date: DateTime.parse(json["date"]),
image: json["image"],
description: json["description"],
category: json["category"],
price: json["price"],
);
}
這是我的示例 API
[
{
"title": "iphone 6s",
"date": "2021-07-11T15:51:35.289193Z",
"image": "/media/products/IMG_20210227_002515.jpg",
"description": "iphone 6s \r\nDisplay: 4.7\"\r\nRam-2GB\r\nROM-64GB",
"category": 2,
"price": 10000
},
{
"title": "iphone 6s again",
"date": "2021-07-11T15:52:22.457555Z",
"image": "/media/products/IMG_20210227_002515_jtKsLrL.jpg",
"description": "iphone 6s \r\nscru chara phone",
"category": 2,
"price": 5500
},
{
"title": "pegion",
"date": "2021-08-09T16:37:18.410878Z",
"image": "/media/products/download_gQUBVZK.png",
"description": "this is a pegion, cinese owal",
"category": 3,
"price": 3000
},
{
"title": "pulser",
"date": "2021-08-25T06:14:58.402376Z",
"image": "/media/products/50340732_332072787517362_7912562101313339392_n.jpg",
"description": "bajaj pulser ,fbhfubfj",
"category": 4,
"price": 100000
}
]
我也用過 futureBuilder ：
late Future<Welcome> futureProduct;
@override
void initState() {
super.initState();
futureProduct = fetchProduct();
}
uj5u.com熱心網友回復：
這是因為您的 API 不會回傳單個Welcome專案，而是回傳多個Welcome專案。
您可以調整fetchProduct方法以回傳 a List<Welcome>：
Future<List<Welcome>> fetchProducts() async {
final response = await http.get(Uri.parse(
'https://api.azabazar.com/api/all-products/?fbclid=IwAR0v4BAB_gFTcpU7Jjqg_t0MnUkUxq8sWPgLj1BHrmOOq_Nd132mz9F8iSU'));
if (response.statusCode == 200) {
// If the server did return a 200 OK response,
// then parse the JSON.
return [
for (final item in jsonDecode(response.body)) Welcome.fromJson(item),
];
} else {
// If the server did not return a 200 OK response,
// then throw an exception.
throw Exception('Failed to load album');
}
}
uj5u.com熱心網友回復：
您的問題出return Welcome.fromJson(jsonDecode(response.body));在這一行，因為您從 api 接收串列回應，但您正在使用 Map 進行決議，因此請執行以下更改，
- 使用以下更新類
//add this line
List<Welcome> welcomeFromJson(String str) => List<Welcome>.from(json.decode(str).map((x) => Welcome.fromJson(x)));
//add this line
String welcomeToJson(List<Welcome> data) => json.encode(List<dynamic>.from(data.map((x) => x.toJson())));
class Welcome {
Welcome({
required this.title,
required this.date,
required this.image,
required this.description,
required this.category,
required this.price,
});
final String title;
final DateTime date;
final String image;
final String description;
final int category;
final int price;
factory Welcome.fromJson(Map<String, dynamic> json) => Welcome(
title: json["title"],
date: DateTime.parse(json["date"]),
image: json["image"],
description: json["description"],
category: json["category"],
price: json["price"],
);
Map<String, dynamic> toJson() => {
"title": title,
"date": date.toIso8601String(),
"image": image,
"description": description,
"category": category,
"price": price,
};
}
- 在決議字串的地方使用這個函式
Future<Welcome> fetchProduct() async {
final response = await http.get(Uri.parse(
'https://api.azabazar.com/api/all-products/?fbclid=IwAR0v4BAB_gFTcpU7Jjqg_t0MnUkUxq8sWPgLj1BHrmOOq_Nd132mz9F8iSU'));
if (response.statusCode == 200) {
// If the server did return a 200 OK response,
// then parse the JSON.
return welcomeFromJson(response.body);<-- change in this line
} else {
// If the server did not return a 200 OK response,
// then throw an exception.
throw Exception('Failed to load album');
}
}
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