ColumnTypeConverter

Marks a function as a column type converter.

Converter functions help Room support types beyond the built-in primitives (String, ByteArray) and enums. @ColumnTypeConverter functions convert column values when reading from a query result or binding parameters into a statement.

Each converter function must receive one parameter and have a non-Unit return type. A class can have as many @ColumnTypeConverter functions as needed.

object Converters {
    @ColumnTypeConverter
    fun fromTimestamp(value: Long?): Date? {
        return value?.let { Date(it) }
    }

    @ColumnTypeConverter
    fun dateToTimestamp(date: Date?): Long? {
        return date?.getTime()
    }
}

Summary

ColumnTypeConverter()