Type Converters

What are type converters

• Type converters are used to store complex data in the database.
• Retrieving the complex data from the database.
• Type converts acts as a layer between the database and the tables.
• Here we specify a mechanism to convert to and convert from` database.
• We define a custom Type converter class.

class DateConverter {

  @TypeConverter
  fun fromTimestamp(value: Long?): Date? {
    return Date(value ?: 0)
  }

  @TypeConverter
  fun dateToTimestamp(date: Date?): Long = date?.time ?: 0
}

• For the property name, we annotate with a @TypeConverters annotation that holds the converter class defined.

@Parcelize
@Entity
data class Review(
    @PrimaryKey
    val id: String = UUID.randomUUID().toString(),
    val bookId: String,
    val rating: Int,
    val notes: String,
    val imageUrl: String,
    @TypeConverters(DateConverter::class)
    val lastUpdatedDate: Date,
    @TypeConverters(ReadingEntryConverter::class)
    val entries: List<ReadingEntry>
) : Parcelable