JSONB support (PostgreSQL)

jsonb.kt

import kotlinx.serialization.KSerializer
import kotlinx.serialization.json.Json
import kotlinx.serialization.serializer
import org.jetbrains.exposed.sql.Column
import org.jetbrains.exposed.sql.ColumnType
import org.jetbrains.exposed.sql.Table
import org.jetbrains.exposed.sql.statements.api.PreparedStatementApi
import org.postgresql.util.PGobject

inline fun <reified T : Any> Table.jsonb(
    name: String,
    kSerializer: KSerializer<T> = serializer(),
    json: Json
): Column<T> = this.jsonb(
    name = name,
    stringify = { json.encodeToString(kSerializer, it) },
    parse = { json.decodeFromString(kSerializer, it) }
)

fun <T : Any> Table.jsonb(name: String, stringify: (T) -> String, parse: (String) -> T): Column<T> =
    registerColumn(name, JsonbColumnType(stringify, parse))

class JsonbColumnType<T : Any>(private val stringify: (T) -> String, private val parse: (String) -> T) : ColumnType() {
    override fun setParameter(stmt: PreparedStatementApi, index: Int, value: Any?) {
        val obj = PGobject()
        obj.type = "jsonb"
        if (value != null) {
            obj.value = value as String
        }
        stmt[index] = obj
    }
    override fun sqlType(): String = "jsonb"
    override fun valueFromDB(value: Any): Any {
        return when (value) {
            is PGobject -> parse(value.value ?: "")
            is Map<*, *> -> value
            is List<*> -> value
            is Set<*> -> value
            is Array<*> -> value
            else -> {
                println("unhandled value type: ${value::class}")
                value
            }
        }
    }

    @Suppress("UNCHECKED_CAST")
    override fun notNullValueToDB(value: Any) = stringify(value as T)

    override fun valueToString(value: Any?): String = when (value) {
        is Iterable<*> -> notNullValueToDB(value)
        else -> super.valueToString(value)
    }
}