firebase - 在 Flutter 中映射 Firestore 中的映射字段对象

Question

这是我的数据的样子。我正在尝试将 Firestore 中的 map 字段对象转换为 flutter。

如果我的Firestore数据库中没有rating map，我可以很方便的使用下面的代码在Flutter中转换数据

firestore.collection('test').doc('I1raMaJArb1sWXWqQErE')
          .snapshots().listen((snapshot) {
        if (snapshot.docs != null) {
          var map = snapshot.docs;
          if (map != null) {
            map.forEach((change) {
              Review review = Review.fromJson(change.data());
            });
          }

但是对于 Firestore 中的评分 map ，我不确定如何转换它。任何人都可以分享他们如何将 Firestore 中的 map 数据类型转换为 flutter 吗？提前致谢!

下面显示了模型的代码。

class Reviews {
  String UserID;
  String UserName;
//what do I put for the rating

  Review({
    this.UserID,
    this.UserName
//what do I put for the rating
});

 factory ChatChannel.fromJson(Map<dynamic, dynamic> json) => ChatChannel(
      UserID: json['UserID'],
      UserName: json['UserName'],
//what do I put for the rating

 );

  Map<String, dynamic> toJson() => {
    "UserID": UserID,
    "UserName": UserName,
//what do I put for the rating

);
}

Answer 1

您可以创建评级模型并在评论模型中添加其参数。 看看下面的代码。

    class Reviews {
      String UserID;
      String UserName;
      Ratings ratings;
      Review({
        this.UserID,
        this.UserName
    //what do I put for the rating
    });
    
     factory ChatChannel.fromJson(Map<dynamic, dynamic> json) => ChatChannel(
          UserID: json['UserID'],
          UserName: json['UserName'],
          Ratings: Ratings.fromJson(json['ratings'])
     );
    
      Map<String, dynamic> toJson() => {
        "UserID": UserID,
        "UserName": UserName,
         "ratings": ratings.toJson(),
    
     );
   }

class Ratings{
  String oneStar;
  String twoStar;
  String threeStar;
  Ratings({this.oneStar, this.twoStar,this.threeStar});

factory Ratings.fromJson(Map<dynamic, dynamic> json) => Ratings(
   oneStar: json['1-star'],
   twoStar: json['2-star'],
   threeStar: json['3-star'],
  );

Map<String, dynamic> toJson() => {
   "1-star": oneStar,
   "2-star": twoStar,
   "3-star": threeStar,
);
}