Added fromJson, toJson

lib/data/dto/game.dart

@@ -21,4 +21,21 @@ class Game {
   String toString() {
     return 'Game{\n\tid: $id,\n\tname: $name,\n\tplayers: $players,\n\tgroup: $group,\n\twinner: $winner\n}';
   }
+
+  /// Creates a Game instance from a JSON object.
+  Game.fromJson(Map<String, dynamic> json)
+    : id = json['id'],
+      name = json['name'],
+      players = json['players'] != null
+          ? (json['players'] as List)
+                .map((playerJson) => Player.fromJson(playerJson))
+                .toList()
+          : null,
+      group = json['group'] != null ? Group.fromJson(json['group']) : null,
+      winner = json['winner'] ?? '';
+
+  /// Converts the Game instance to a JSON object.
+  String toJson() {
+    return 'Game{id: $id,name: $name,players: $players,group: $group,winner: $winner}';
+  }
 }

lib/data/dto/group.dart

@@ -13,4 +13,17 @@ class Group {
   String toString() {
     return 'Group{id: $id, name: $name,members: $members}';
   }
+
+  /// Creates a Group instance from a JSON object.
+  Group.fromJson(Map<String, dynamic> json)
+    : id = json['id'],
+      name = json['name'],
+      members = (json['members'] as List)
+          .map((memberJson) => Player.fromJson(memberJson))
+          .toList();
+
+  /// Converts the Group instance to a JSON object.
+  String toJson() {
+    return 'Group{id: $id, name: $name,members: $members}';
+  }
 }

lib/data/dto/player.dart

@@ -10,4 +10,14 @@ class Player {
   String toString() {
     return 'Player{id: $id,name: $name}';
   }
+
+  /// Creates a Player instance from a JSON object.
+  Player.fromJson(Map<String, dynamic> json)
+    : id = json['id'],
+      name = json['name'];
+
+  /// Converts the Player instance to a JSON object.
+  String toJson() {
+    return 'Player{id: $id,name: $name}';
+  }
 }