颤振:列表上的映射方法无效

Question

我用json_serializer创建了一个模型类

@JsonSerializable()
class DataBaseModel {
  String? word;
  String? explain;
  List<Phonetics>? phonetics;
  List<Meanings>? meanings;
  String? uid;
  String? path;
  Configs? configs;
  String? phonetic;
  DataBaseModel({
    String? word,
    String? explain,
    List<Phonetics>? phonetics,
    List<Meanings>? meanings,
    String? uid,
    String? path,
    Configs? configs,
    String? phonetic,
  });

  factory DataBaseModel.fromJson(Map<String, dynamic> json) =>
      _$DataBaseModelFromJson(json);

  Map<String, dynamic> toJson() => _$DataBaseModelToJson(this);
}

现在，我想作为这个类创建一个实例，因此在我的一个列表中，我使用Map方法返回该类的列表：

final vocabs = dbclient.bularyBox.values
    .toList()
    .map((e) => DataBaseModel(
          uid: "e.uid ?? " "",
          word: "e.word",
          path: "e.path",
          explain: "e.explain",
          phonetic: "e.phonetic",
     
        ))
    .toList();

final newjson = vocabs.map((e) => e.toJson()).toList();

但是vocabs属性是null

​

​

Answer 1

问题是，您从未在模型类的构造函数中分配属性：

DataBaseModel({
  String? word,
  String? explain,
  List<Phonetics>? phonetics,
  List<Meanings>? meanings,
  String? uid,
  String? path,
  Configs? configs,
  String? phonetic,
});

应：

DataBaseModel({
  this.word,
  this.explain,
  this.phonetics,
  this.meanings,
  this.uid,
  this.path,
  this.configs,
  this.phonetic,
});