Add something to easily handle the mapping of Enum in database about ktorm HOT 6 CLOSED

fun <E : Any, C : Enum<C>> BaseTable<E>.enum(name: String, typeRef: TypeReference<C>): BaseTable<E>.ColumnRegistration<C> {
    return registerColumn(name, EnumSqlType(typeRef.referencedType as Class<C>))
}

class EnumSqlType<C : Enum<C>>(val enumClass: Class<C>) : SqlType<C>(Types.VARCHAR, "varchar") {
    private val valueOf = enumClass.getDeclaredMethod("valueOf", String::class.java)

    override fun doSetParameter(ps: PreparedStatement, index: Int, parameter: C) {
        ps.setString(index, parameter.name)
    }

    override fun doGetResult(rs: ResultSet, index: Int): C? {
        return rs.getString(index)?.takeIf { it.isNotBlank() }?.let { enumClass.cast(valueOf(null, it)) }
    }
}

object Employees : Table<Nothing>("t_employee") {
    // ...
    val sex by enum("sex", typeRef<Sex>())
}

interface HasCodeEnum {
    val code: Int
}

inline fun <reified T : HasCodeEnum> Int?.ofEnum(): T? {
    if (this == null) return null
    val enums = T::class.java.enumConstants
    return enums.firstOrNull { it.code == this }
}

data class EnumSqlType<T : HasCodeEnum>(
        val enumType: KClass<T>
) : SqlType<T>(Types.TINYINT, typeName = "enum") {

    override fun doSetParameter(
            ps: PreparedStatement,
            index: Int,
            parameter: T ) {

        ps.setInt(index, parameter.code)
    }

    override fun doGetResult(
            rs: ResultSet,
            index: Int ): T? {

        val code = rs.getInt(index)
        val enums = enumType.java.enumConstants
        return enums.firstOrNull { it.code == code }
    }
}