Step 1 - Object shape

import 'dart:convert';

void main() {
  final raw = '''
  {
    "user": {"id": "1", "name": "Asha"},
    "tags": ["dart", "json"]
  }
  ''';
  final root = jsonDecode(raw) as Map<String, dynamic>;
  final user = root['user'] as Map<String, dynamic>;
  final tags = root['tags'] as List<dynamic>;
  print(user['name']);
  print(tags.first);
}

Step 2 - List of objects

import 'dart:convert';

void main() {
  final raw = '[{"id":"1"},{"id":"2"}]';
  final list = jsonDecode(raw) as List<dynamic>;
  for (final item in list) {
    final m = item as Map<String, dynamic>;
    print(m['id']);
  }
}

Step 3 - Prefer model types at the boundary

• Parse once into your User, Todo, etc., then the rest of the app uses strong types.

Practice tasks

• Decode nested {"data":{"items":[1,2,3]}} and sum the items.
• Write a helper Map<String, dynamic>? asMap(Object? value) that returns null if not a map.