R2DBCと列挙型（PostgreSQL）

org.springframework.data:spring-data-r2dbc:1.0.0.RELEASEでテスト済み およびio.r2dbc:r2dbc-postgresql:0.8.1.RELEASE 。

Kotlinバージョン。

1. 列挙型クラスを定義する

   enum class Mood {
       UNKNOWN,
       HAPPY,
       SAD
   }
   

2. カスタムコーデックを作成する

   class MoodCodec(private val allocator: ByteBufAllocator) :  Codec<Mood> {
       override fun canEncodeNull(type: Class<*>): Boolean = false
   
       override fun canEncode(value: Any): Boolean = value is Mood
   
       override fun encode(value: Any): Parameter {
           return Parameter(Format.FORMAT_TEXT, oid) {
               ByteBufUtils.encode(allocator, (value as Mood).name)
           }
       }
   
       override fun canDecode(dataType: Int, format: Format, type: Class<*>): Boolean = dataType == oid
   
       override fun decode(buffer: ByteBuf?, dataType: Int, format: Format, type: Class<out Mood>): Mood? {
           buffer ?: return null
           return Mood.valueOf(ByteBufUtils.decode(buffer))
       }
   
       override fun type(): Class<*> = Mood::class.java
   
       override fun encodeNull(): Parameter =
           Parameter(Format.FORMAT_TEXT, oid, Parameter.NULL_VALUE)
   
       companion object {
           // Get form `select oid from pg_type where typname = 'mood'`
           private const val oid = YOUR_ENUM_OID
       }
   }
   

3. コーデックを登録する

   runtimeOnly("io.r2dbc:r2dbc-postgresql")の変更が必要になる場合があります implementation("io.r2dbc:r2dbc-postgresql")へ

   @Configuration
   @EnableR2dbcRepositories
   class AppConfig : AbstractR2dbcConfiguration() {
       override fun connectionFactory(): ConnectionFactory = PostgresqlConnectionConfiguration.builder()
           .port(5432) // Add your config here.
           .codecRegistrar { _, allocator, registry ->
               registry.addFirst(MoodCodec(allocator))
               Mono.empty()
           }.build()
           .let { PostgresqlConnectionFactory(it) }
   }