在Dart中使用json_serializer处理将地图序列化为JSON的正确方法是什么？

Question

我一直试图通过调用类的toJson函数来返回Map，但是我得到了 NoSuchMethodError：类'_InternalLinkedHashMap'没有实例方法'toJson'。 所以我假设这是不正确的。 examples仅包含可以转换为单个值的单个值，但不处理列表或地图。 那么在Dart中使用json_serializer处理将序列化为JSON的映射的正确方法是什么？

我要序列化的类：

class StudentDailyReport {
  final DocumentReference documentReference;
  Student student;

  // CheckIn
  String attendanceStatus;
  bool checkInChanged;
  DateTime checkedInTime;

  DateTime date;

  // CheckOut
  bool get checkedOut => this.attendanceStatus == AttendanceStatus.checkedOut;
  bool checkOutChanged;
  DateTime checkedOutTime;

  // Mood
  Mood mood;
  bool moodHasChanged;
  TextEditingController moodController;

  // Supplies
  Supplies supplies;

  // Notes
  Note note;
  TextEditingController noteController;
  bool noteChanged;

  // Meals
  Map<Meal, MealRecord> mealRecords;
  bool mealsChanged;

  // Health
  Map<int, HealthEntry> healthEntries;
  bool healthChanged;

  //PottyLog
  PottyLog pottyLog;

  bool get pottyLogChanged => pottyLog.hasChanged;

  ActivityLog activityLog;

  bool get activityLogChanged => activityLog.hasChanged;

  set activityLogChanged(bool value) =>
      activityLog = activityLog.copyWith(hasChanged: value);

  List<CaptionedPhoto> photos;

  factory StudentDailyReport.initialFromStudent(Student student) {
    return StudentDailyReport(
        student: student,
        moodController: TextEditingController(),
        healthEntries: {0: HealthEntry.empty()},
        supplies: Supplies(),
        pottyLog: PottyLog.empty(),
        activityLog: ActivityLog());
  }

  StudentDailyReport.fromDocument(DocumentSnapshot document)
      : documentReference = document.reference {
    Map json = document.data;
    // Ensure that the student has been converted and inserted as a student object
    // into the json before calling.
    this.student = json['student'];
    this.mood = json['mood'] != null ? Mood.fromJson(json['mood']) : Mood();
    this.attendanceStatus = json['attendanceStatus'] ?? AttendanceStatus.none;
    this.checkedInTime = json['checkedInTime'] != null
        ? (json['checkedInTime'] as Timestamp).toDate()
        : null;
    this.checkedOutTime = json['checkedOutTime'] != null
        ? (json['checkedOutTime'] as Timestamp).toDate()
        : null;
    this.supplies = json['supplies'] != null
        ? Supplies.fromJson(json['supplies'])
        : Supplies();
    this.note = json['note'] != null ? Note.fromJson(json['note']) : Note();
    noteController = TextEditingController(text: note.comment);
    this.mealRecords = MealRecord.mapFromJsonList(json['mealRecords']);
    this.healthEntries = json['healthEntries'] != null
        ? (json['healthEntries'] as List)
            .map((json) => HealthEntry.fromJson(json))
            .toList()
            .asMap()
        : {0: HealthEntry.empty()};
    this.pottyLog = json["pottyLog"] != null
        ? PottyLog.fromJson(json["pottyLog"])
        : PottyLog();
    this.activityLog = json["activityLog"] != null
        ? ActivityLog.fromJson(json["activityLog"])
        : ActivityLog();
    this.photos = json['photos'] != null
        ? (json['photos'] as List)
            .map((photoJson) => CaptionedPhoto.fromJson(photoJson))
            .toList()
        : List<CaptionedPhoto>();
    this.checkInChanged = false;
    this.checkOutChanged = false;
    this.healthChanged = false;
    this.mealsChanged = false;
    this.noteChanged = false;
    this.moodHasChanged = false;
    this.moodController = TextEditingController();
  }

  bool validateMeals() {
    return mealRecords.values.any((mealRecord) => !mealRecord.isValid);
  }

  /// Used to indicate when changes need to be saved.
  bool get hasUnsavedChanges {
    bool result;
    if (moodHasChanged == null ||
        checkInChanged == null ||
        supplies.suppliesHasChanged == null ||
        checkOutChanged == null ||
        noteChanged == null ||
        checkOutChanged == null ||
        mealsChanged == null ||
        healthChanged == null ||
        pottyLogChanged == null ||
        activityLogChanged == null) {
      debugPrint("One of these is null!");
    }
    try {
      result = moodHasChanged ||
          checkInChanged ||
          supplies.suppliesHasChanged ||
          checkOutChanged ||
          noteChanged ||
          checkOutChanged ||
          mealsChanged ||
          healthChanged ||
          pottyLogChanged ||
          activityLogChanged;
    } on Exception {
      return false;
    }

    return result;
  }

  StudentDailyReport({
    this.documentReference,
    this.student,
    this.date,
    // Mood
    this.mood = const Mood(),
    this.moodHasChanged = false,
    this.moodController,

    // Check In
    this.attendanceStatus = AttendanceStatus.none,
    this.checkInChanged = false,
    this.checkedInTime,

    //Check Out
    this.checkOutChanged = false,
    this.checkedOutTime,

    // Supplies
    this.supplies,
    this.mealRecords = const {},
    this.mealsChanged = false,

    // Notes
    this.noteController,
    this.note = const Note.empty(),
    this.noteChanged = false,

    // Health
    this.healthEntries,
    this.healthChanged = false,

    //PottyLog
    this.pottyLog,

    //ActivityLog
    this.activityLog,
    this.photos,
  }) {
    // assertions
    if (attendanceStatus == AttendanceStatus.present) {
      assert(checkedInTime != null);
    }
    if (attendanceStatus == AttendanceStatus.checkedOut) {
      assert(checkedOutTime != null);
    }
    this.date ??= DateTime.now();
    this.noteController = TextEditingController();
    this.moodController = TextEditingController();
  }

  StudentDailyReport copyWith({
    DocumentReference documentReference,
    Mood mood,
    bool moodChanged,
    bool checkInChanged,
    DateTime checkedInTime,
    bool checkedOut,
    DateTime checkedOutTime,
    bool checkOutChanged,
    TextEditingController moodController,
    String attendanceStatus,
    Note note,
    Supplies supplies,
    TextEditingController notesController,
    bool notesChanged,
    TextEditingController suppliesController,
    bool suppliesChanged,
    bool hasUnsavedChanges,
    Map<Meal, MealRecord> mealRecords,
    bool mealsChanged,
    Map<int, HealthEntry> todaysHealthEntries,
    bool healthChanged,
    PottyLog pottyLog,
    bool pottyLogChanged,
    ActivityLog activityLog,
    bool activityLogChanged,
    List<CaptionedPhoto> photos,
    DateTime date,
  }) {
    return StudentDailyReport(
        documentReference: documentReference ?? this.documentReference,
        student: this.student,
        mood: mood ?? this.mood,
        moodHasChanged: moodChanged ?? this.moodHasChanged,
        checkInChanged: checkInChanged ?? this.checkInChanged,
        attendanceStatus: attendanceStatus ?? this.attendanceStatus,
        checkedInTime: (attendanceStatus == AttendanceStatus.present &&
                checkedInTime == null)
            ? DateTime.now()
            : checkedInTime ?? this.checkedInTime,
        moodController: this.moodController,
        note: note ?? this.note,
        noteController: this.noteController,
        noteChanged: noteChanged ?? this.noteChanged,
        supplies: supplies ?? this.supplies,
        checkOutChanged: checkOutChanged ?? this.checkOutChanged,
        checkedOutTime: attendanceStatus == AttendanceStatus.present &&
                checkedOutTime == null
            ? DateTime.now()
            : this.checkedOutTime,
        mealRecords: mealRecords ?? this.mealRecords,
        mealsChanged: mealsChanged ?? this.mealsChanged,
        healthEntries: todaysHealthEntries ?? this.healthEntries,
        healthChanged: healthChanged ?? this.healthChanged,
        pottyLog: () {
          PottyLog newPottyLog = pottyLog ??= this.pottyLog;
          if (pottyLogChanged == false) {
            return newPottyLog.copyWith(hasChanged: false);
          }
          return newPottyLog;
        }(),
        activityLog: activityLog ?? this.activityLog,
        photos: photos ?? this.photos,
        date: date ?? this.date);
  }

  String get fullName => student.fullName;

  Map<String, dynamic> toJson() {
    Map<String, dynamic> data = {};

    if (this.mood != null && this.mood.mood != "" && this.moodHasChanged) {
      data["mood"] = this.mood.toJson();
    }

    // attendance
    if (this.checkInChanged || this.checkOutChanged) {
      data["attendanceStatus"] = this.attendanceStatus;
    }
    if (this.checkInChanged) {
      assert(checkedInTime != null);
      data['checkedInTime'] = Timestamp.fromDate(this.checkedInTime);
    }
    if (this.checkOutChanged) {
      assert(checkedOutTime != null);
      data['checkedOutTime'] = Timestamp.fromDate(this.checkedOutTime);
    }
    if (this.supplies.suppliesHasChanged) {
      data["supplies"] = this.supplies.toJson();
    }
    if (this.mealsChanged) {
      data['mealRecords'] = this
          .mealRecords
          .values
          .map((mealRecord) => mealRecord.toJson())
          .toList();
    }
    if (this.noteChanged) {
      data['note'] = this.note.toJson();
    }
    data['student'] = this.student.documentReference;
    if (healthChanged) {
      data['healthEntries'] = healthEntries.values
          .map((healthEntry) => healthEntry.toJson())
          .toList();
    }
    if (this.pottyLogChanged) {
      data['pottyLog'] = this.pottyLog.toJson();
    }
    if (this.activityLogChanged) {
      data['activityLog'] = this.activityLog.toJson();
    }
    return data;
  }

  StudentDailyReport updateWith(DocumentSnapshot documentChange) {
    Map json = documentChange.data;

    return StudentDailyReport(
        documentReference: documentChange.reference,
        student: student,
        mood: json['mood'] != null ? Mood.fromJson(json['mood']) : mood,
        attendanceStatus: json['attendanceStatus'] ?? attendanceStatus,
        checkedInTime:
            (json['checkedInTime'] as Timestamp)?.toDate() ?? checkedInTime,
        checkedOutTime:
            (json['checkedOutTime'] as Timestamp)?.toDate() ?? checkedOutTime,
        supplies: json['supplies'] != null
            ? Supplies.fromJson(json['supplies'])
            : supplies,
        note: json['note'] != null ? Note.fromJson(json['note']) : note,
        mealRecords: MealRecord.mapFromJsonList(json['mealRecords']),
        healthEntries: json['healthEntries'] != null
            ? (json['healthEntries'] as List)
                .map((json) => HealthEntry.fromJson(json))
                .toList()
                .asMap()
            : healthEntries,
        pottyLog: json["pottyLog"] != null
            ? PottyLog.fromJson(json["pottyLog"])
            : pottyLog,
        activityLog: json["activityLog"] != null
            ? ActivityLog.fromJson(json["activityLog"])
            : activityLog,
        photos: json['photos'] != null
            ? (json['photos'] as List)
                .map((json) => CaptionedPhoto.fromJson(json))
                .toList()
            : []);
  }

  @override
  String toString() {
    return "Report for $fullName";
  }
}

Answer 1

目前，我们在地图中不支持“复杂”键，例如Meal。

为此问题加注星标-https://github.com/dart-lang/json_serializable/issues/396