Dart 2 and parsing json - dart

Question

Im trying to parse json into a list of Products using Dart 2 for web.
I have the following Class:
class Product {
final String Problem;
final String Owner;
final String Description;
const Product({
this.Problem,
this.Owner,
this.Description,
});
factory Product.parse(Map<String, dynamic> json) {
print(json);
return new Product(
Problem: json["Problem"],
Owner: json["Owner"],
Description: json["Description"]
);
}
}
And I am trying to parse this using:
Stream<Product> getProducts() async* {
final payload = await HttpRequest.getString("products.json");
print(payload);
//var _json = (json.decode(payload));
print("break");
var list = json.decode(payload);
print(list);
//print(list);
final productList = (json.decode(payload) as List).cast<Map<String, dynamic>>();
}
However this fails with this error:
EXCEPTION: Type '_JsonMap' is not a subtype of expected type
'List'.
I can see that I have a list[Symbol(_original)] when I debug, but when I try to evaluate this, I returns as undefined.
I also tried
List list = json.decode(payload) as List;
List<dynamic> list = json.decode(payload);
List<dynamic> list = json.decode(payload) as List<dynamic>;
var list = (json.decode(payload)).cast<Map<String, dynamic>>();
var list = (json.decode(payload)).cast<Map<dynamic, dynamic>>();
but get the same error.
Json
{
"Product_One": {
"Owner": "test",
"Description": "test description",
"Theme_Objective": "test objective",
"Technical_details": "test technical details",
"Problem": "test",
"Solution": "test"
}
}

Answer 1

Your JSON does not contain any list, it's all maps.
When you try to cast a Map to List, it has to fail since maps are not lists.
Maybe you want to do:
final productList = (jsonDecode(payload) as Map).values.toList();
This gives you a list of the product maps, without the names that you don't appear to be using anyway.