Access nested objects in json using json_serializable in Dart - json

Question

Trying to convert my json to objects in Dart/Flutter using the json_serializable. I cannot seem to find a way to access a nested ID (data is coming from MongoDB thus the $ in the json).
Here is the json:
{
"_id": {
"$oid": "5c00b227" <-- this is what I am trying to access
},
"base": 1,
"tax": 1,
"minimum": 5,
"type": "blah"
}
Result:
class Thing {
final int id;
final String base;
final String tax;
final String type;
final int minimum;
}

Answer 1

It is not possible with json_serializable package itself. You have to create separate objects for getting this nested data.
Look the discussion here
https://github.com/google/json_serializable.dart/issues/490
But, there is possible way to get nested fields with added converter (solution was found here https://github.com/google/json_serializable.dart/blob/master/example/lib/nested_values_example.dart)
import 'package:json_annotation/json_annotation.dart';
part 'nested_values_example.g.dart';
/// An example work-around for
/// https://github.com/google/json_serializable.dart/issues/490
#JsonSerializable()
class NestedValueExample {
NestedValueExample(this.nestedValues);
factory NestedValueExample.fromJson(Map<String, dynamic> json) =>
_$NestedValueExampleFromJson(json);
#_NestedListConverter()
#JsonKey(name: 'root_items')
final List<String> nestedValues;
Map<String, dynamic> toJson() => _$NestedValueExampleToJson(this);
}
class _NestedListConverter
extends JsonConverter<List<String>, Map<String, dynamic>> {
const _NestedListConverter();
#override
List<String> fromJson(Map<String, dynamic> json) => [
for (var e in json['items'] as List)
(e as Map<String, dynamic>)['name'] as String
];
#override
Map<String, dynamic> toJson(List<String> object) => {
'items': [
for (var item in object) {'name': item}
]
};
}

Answer 2

try this,
class Thing {
int id;
String base;
String tax;
String type;
int minimum;
Thing({
this.id,
this.base,
this.tax,
this.type,
this.minimum,
});
factory Thing.fromJson(Map<String, dynamic> json) {
return Thing(
id: json['_id']["oid"],
base: json['base'].toString(),
tax: json['tax'].toString(),
type: json['type'].toString(),
minimum: json['minimum'],
);
}
}