将json转换为飞镖答案

【问题标题】：convert json to dart将json转换为飞镖
【发布时间】：2021-04-12 08:22:08
【问题描述】：

我是 Flutter 的初学者，我只想知道如何在控制台中打印 productA 和 220。下面是json文件，下面也是创建dart文件。

{
  "status": true,
  "message": "Data returned successfull",
  "data": {
    "products": [
      {
        "productName": "productA",
        "productPrice": "220.00",
      }
    ]
  }
}

产品.dart

class Product {
  bool status;
  String message;
  Data data;

  Product({this.status, this.message, this.data});

  Product.fromJson(Map<String, dynamic> json) {
    status = json['status'];
    message = json['message'];
    data = json['data'] != null ? new Data.fromJson(json['data']) : null;
  }
}

class Data {
  List<Products> products;

  Data({this.products});

  Data.fromJson(Map<String, dynamic> json) {
    if (json['products'] != null) {
      products = new List<Products>();
      json['products'].forEach((v) {
        products.add(new Products.fromJson(v));
      });
    }
  }
}

class Products {
  String prodName;
  String prodRkPrice;

  Products({this.prodName, this.prodRkPrice});

  Products.fromJson(Map<String, dynamic> json) {
    prodName = json['prodName'];
    prodRkPrice = json['prodRkPrice'];
  }
}

但仍然不知道如何打印这些值。


fetchData() async {
    try {
      String extractedData =
          await http.get('json url').toString();

      final parsed = jsonDecode(extractedData).cast(Map<String, dynamic>());

      final products = Product.fromJson(parsed);

      print(products);

      //print(json.decode(response.body));
      //print(response[0]);
    } catch (error) {
      throw (error);
    }
  }

我曾尝试使用此方法，但出现错误，不知道如何解析和打印这些值？请帮助我，我是 Flutter 的初学者

【问题讨论】：

标签： json flutter dart

【解决方案1】：

将您的 fetchData 更改为：

Future<void> fetchData() async {
  try {
    Response response = await http.get('json url'); //getting the response without .toString
    Map<String, dynamic> extractedData = jsonDecode(response.body); //converting the response

    Product products = Product.fromJson(extractedData);

    products.data.products.forEach((product) {
      print(product.prodName);
      print(product.prodRkPrice);
    });

  } catch (error) {
    throw (error);
  }
}

只要记住在Products类中匹配api的相同属性名即可：

Products.fromJson(Map<String, dynamic> json) {
    prodName = json['productName'];
    prodRkPrice = json['productPrice'];
}

【讨论】：

【解决方案2】：

这应该可行：

Map<String, dynamic> message = jsonDecode('{"status": true,"message": "Data returned successfull","data": {"products": [{"productName": "productA","productPrice": "220.00"}]}}');
print(message["data"]["products"][0]["productName"]);

你遇到了什么错误？

【讨论】：

【解决方案3】：

请试试这个function

fetchData() async {
    try {
      var extractedData = await http.get('json url');
      Product finalResponse = Product.fromJson(jsonDecode(extractedData.body)); 
      print(finalResponse.products[0].productName);                   
      print(finalResponse);    
    } catch (error) {
      throw (error);
    }
  }

【讨论】：

【解决方案4】：

String urlBase = "https://.....";

未来的 fetchData 异步 {

var jsonResponse;
var response = await http.get("$urlBase");

if (response != null && response.statusCode == 200) {
  jsonResponse = json.decode(response.body);

 Object obj= jsonDecode(response.body);

  return obj;
} else {
  //do something else
}

}

【讨论】：

【解决方案5】：

要访问 Product A 和 220，首先您应该将 json 响应转换为 dart 对象。我Try free online JSON to Dart convertor 这是飞镖对象类

class product_model {
  bool status;
  String message;
  Data data;

  product_model({this.status, this.message, this.data});

  product_model.fromJson(Map<String, dynamic> json) {
    status = json['status'];
    message = json['message'];
    data = json['data'] != null ? new Data.fromJson(json['data']) : null;
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['status'] = this.status;
    data['message'] = this.message;
    if (this.data != null) {
      data['data'] = this.data.toJson();
    }
    return data;
  }
}

class Data {
  List<Products> products;

  Data({this.products});

  Data.fromJson(Map<String, dynamic> json) {
    if (json['products'] != null) {
      products = new List<Products>();
      json['products'].forEach((v) {
        products.add(new Products.fromJson(v));
      });
    }
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    if (this.products != null) {
      data['products'] = this.products.map((v) => v.toJson()).toList();
    }
    return data;
  }
}

class Products {
  String productName;
  String productPrice;

  Products({this.productName, this.productPrice});

  Products.fromJson(Map<String, dynamic> json) {
    productName = json['productName'];
    productPrice = json['productPrice'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['productName'] = this.productName;
    data['productPrice'] = this.productPrice;
    return data;
  }
}

要访问产品 A 和值 220，请使用以下代码。

 final Map<String, dynamic> parsed = await wrapper.get_CategoryFull(catid);
final model = product_model.fromJson(parsed);
     if (model.data.length > 0) {    
       if (model.products.length > 0) {
              for (int i = 0; i < model.products.length; i++) {
                print(" product name " +model.products[i].productName);
                print(" product price " +model.products[i].productPrice);
               
              }
        
            } 
    }

【讨论】：