如何解析扑扑中的杰森地图列表? [英] How to parse List of maps Json in flutter?

问题描述

我有一个Json结构，其中包含三个地图，一个是然后列出产品总数和税额.我必须在颤抖中解析这个json结构.我在模型类上创建的.现在我在类型转换中遇到错误.

I have one Json structure with three maps, one is list of products then total and tax. I have to parse this json structure in flutter. I created on model class. Now i am getting the error in type casting.

如何解决这个问题?

JSON结构:

{
  "products" : [
     {                  
       "cart_id": "7",      
     },          
     {                  
       "cart_id": "7",
     }     
  ],
  "total": 100,
  "tax": 100
}

模型类:

class CartModel {   
    List<Product> produtcts;
    double total;

    CartModel({this.produtcts, this.total});

    factory CartModel.fromJson(Map<String, dynamic> json) {
        var list = json['products'] as List;
        print(list.runtimeType);
        List<Product> products = list.map((i) => 
           Product.fromJson(i)).toList();

        return CartModel(
            produtcts: products, total: json['total'],);
    }
}

class Product {
    String cartId;

    Product({this.cartId,});

    factory Product.fromJson(Map<String, dynamic> json) {
        return Product(     
            productId: json['cart_id'],
        );
    }
}

推荐答案

与其将products数组强制转换为列表，请尝试将其用作 Iterable .

Instead of casting the products array to a list try using it as an Iterable.

对我来说，以下代码有效(请注意， json.decode(String)方法是从 dart:convert 包中导入的):

For me the following code works (note that the json.decode(String) method is imported from the dart:convert package):

var data = '{"products":[{"cart_id": "7"},{ "cart_id": "7"}], "total": 100, "tax": 100}';
var decoded = json.decode(data);   
var cartModel = CartModel.fromJson(decoded);

class CartModel {   
    List<Product> produtcts;
    int total;

    CartModel({this.produtcts, this.total});

    factory CartModel.fromJson(Map<String, dynamic> json) {
        Iterable list = json['products'];
        print(list.runtimeType);
        List<Product> products = list.map((i) => 
           Product.fromJson(i)).toList();

        return CartModel(
            produtcts: products, total: json['total'],);
    }
}

class Product {
    String productId;

    Product({this.productId,});

    factory Product.fromJson(Map<String, dynamic> json) {
        return Product(     
            productId: json['cart_id'],
        );
    }
}

这篇关于如何解析扑扑中的杰森地图列表?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！