在 Firebase 中存储/检索枚举的解决方法是什么？

Question

首先，我认为我在项目后期才开始使用 Firebase 是我的错。

无论如何，我想做的是将 Pub 对象存储到数据库中。它包含各种信息，例如开放时间、评级、设施等。

问题不在于存储，而是每当我尝试从数据库中获取 pubs 列表时，都会遇到这个问题

这是错误。

 com.google.firebase.database.DatabaseException: Could not find enum value of com.example.matasolutions.pintindex.Day for value "Monday"
        at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToEnum(com.google.firebase:firebase-database@@16.1.0:302)
        at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToClass(com.google.firebase:firebase-database@@16.1.0:212)
        at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToType(com.google.firebase:firebase-database@@16.1.0:178)

这是枚举类。

public enum Day {
    MONDAY,TUESDAY,WEDNESDAY,THURSDAY,FRIDAY,SATURDAY,SUNDAY
};

这就是带有枚举的构造函数的样子

public SingleOpeningHours(Day dayOfTheWeek,String openingTime, String closingTime){

        this.dayOfTheWeek = dayOfTheWeek;
        this.openingTime = openingTime;
        this.closingTime = closingTime;

    }

最后，这就是它被添加到列表然后到数据库的方式。

  ArrayList<SingleOpeningHours> singleOpeningHours = new ArrayList<SingleOpeningHours>();

        singleOpeningHours.add(new SingleOpeningHours(Day.MONDAY, "09:00", "00:00"));
        singleOpeningHours.add(new SingleOpeningHours(Day.TUESDAY, "09:00", "01:00"));
        singleOpeningHours.add(new SingleOpeningHours(Day.WEDNESDAY, "09:00", "01:00"));
        singleOpeningHours.add(new SingleOpeningHours(Day.THURSDAY, "09:00","01:00"));
        singleOpeningHours.add(new SingleOpeningHours(Day.FRIDAY, "09:00", "01:00"));
        singleOpeningHours.add(new SingleOpeningHours(Day.SATURDAY, "09:00", "01:00"));
        singleOpeningHours.add(new SingleOpeningHours(Day.SUNDAY, "09:00", "01:00"));

编辑：我有 7 个与正在存储的对象相关联的枚举类。最好的解决方法是什么？先谢谢各位了

Answer 1

Firebase 数据库不支持枚举数据类型。要了解有关支持的数据类型的更多信息，请查看Supported data types

解决方案 1：（最简单） 只需在不进行枚举的情况下使用字符串

将 dayOfTheWeek 更改为字符串

String dayOfTheWeek; // Changed from Day to String

public SingleOpeningHours(String dayOfTheWeek,String openingTime, String closingTime){

    this.dayOfTheWeek = dayOfTheWeek;
    this.openingTime = openingTime;
    this.closingTime = closingTime;

}

并在 singleOpeningHours List 中使用字符串如下，

ArrayList<SingleOpeningHours> singleOpeningHours = new ArrayList<SingleOpeningHours>();

    singleOpeningHours.add(new SingleOpeningHours("MONDAY", "09:00", "00:00"));
    singleOpeningHours.add(new SingleOpeningHours("TUESDAY", "09:00", "01:00"));

解决方案2：将SingleOpeningHours对象中使用的dayOfTheWeek更改为字符串，并使用Enum Class中的name()方法将枚举值转换为字符串

String dayOfTheWeek; // Changed from Day to String
String openingTime;
String closingTime;

public SingleOpeningHours(Day dayOfTheWeek,String openingTime, String closingTime){

this.dayOfTheWeek = dayOfTheWeek.name(); // make sure add .name()
this.openingTime = openingTime;
this.closingTime = closingTime;

}

在 singleOpeningHours 列表中使用枚举 Day（这里没有变化）

ArrayList<SingleOpeningHours> singleOpeningHours = new ArrayList<SingleOpeningHours>();

singleOpeningHours.add(new SingleOpeningHours(Day.MONDAY, "09:00", "00:00"));
singleOpeningHours.add(new SingleOpeningHours(Day.TUESDAY, "09:00", "01:00"));

希望这些解决方案能帮助您解决问题