How to parse List of maps Json in flutter?

Question

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.

How to solve this?

JSON Structure:

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

Model class :

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'],
        );
    }
}

where are you error, Product.fromJson or CartModel.fromJson ? — Augusto
– Augusto, Commented Jun 26, 2019 at 11:56
The error is in cartmodel : type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'List<dynamic>' in type cast — proversion
– proversion, Commented Jun 26, 2019 at 12:00

Maurits van Beusekom · Accepted Answer · 2019-06-26 11:57:59Z

5

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

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'],
        );
    }
}

edited Jun 26, 2019 at 11:57

answered Jun 26, 2019 at 10:57

Maurits van Beusekom

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10 Comments

proversion Over a year ago

The same error, _InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'List<dynamic>' in type cast.

Maurits van Beusekom Over a year ago

@proversion I have updated my answer with an example on how I called the CartModel.fromJson method. This code is working fine, just note that I had to correct some syntax errors in your original question (I have also fixed these in the original question).

proversion Over a year ago

final data = jsonDecode(response.body); final rest = data as List; list = rest.map<CartModel>((json) => CartModel.fromJson(json)).toList();

Maurits van Beusekom Over a year ago

Did you check the result you received from your backend system (the actual JSON)? Does it contain a value for the array? I have tried using jsonDecode() in the above code and works just fine. To me it looks like the json you are trying to parse is slightly different from what you are expecting and thus resulting in the error.

proversion Over a year ago

Map( 3 Items) - 0 -> Products, 1->total , 2 - > tax

|

elgsylvain85 · Accepted Answer · 2020-06-10 21:50:58Z

1

Quite simply :

 List<CartModel> list = new List();
  var jsonlist = jsonDecode(yourJsonString) as List;
  jsonlist.forEach((e) {
    list.add(CartModel.fromJson(e));
  });

answered Jun 10, 2020 at 21:50

elgsylvain85

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