How to save enum field in the database room?

Question

I must write the value from the enum enumeration to the database. An error occurs during compilation. What am I doing wrong?

Cannot figur

Answer 1

You can make a convert to each enum, like this:

class Converters {

     @TypeConverter
     fun toHealth(value: String) = enumValueOf(value)

     @TypeConverter
     fun fromHealth(value: Health) = value.name
}

Or if you prefer store it as SQL integer, you can use ordinal too:

class Converters {

    @TypeConverter
    fun toHealth(value: Int) = enumValues()[value]

    @TypeConverter
    fun fromHealth(value: Health) = value.ordinal
}

Unfortunatally, there is no way to use generics Enum to accomplish this since unbound generics will raise an error Cannot use unbound generics in Type Converters.

Android Room team could seriously add an annotation and a generator for Enums to their kapt compiler.

Finally, annotate a database class, entity class, dao class, dao method, dao method parameter or entity field class with this:

@TypeConverters(Converters::class)