JpaGsonJsonbPostgresql.kt

package com.kmirai.kis.lib

import com.kmirai.kis.Gson
import org.hibernate.HibernateException
import org.hibernate.dialect.PostgreSQL95Dialect
import org.hibernate.engine.spi.SharedSessionContractImplementor
import org.hibernate.usertype.UserType
import org.springframework.util.ObjectUtils
import java.io.Serializable
import java.sql.PreparedStatement
import java.sql.ResultSet
import java.sql.Types

class PostgreSQLWithGson : PostgreSQL95Dialect() {
    init {
        this.registerColumnType(Types.JAVA_OBJECT, "jsonb")
    }
}

class JsonbAsGsonType : UserType {
    override fun hashCode(x: Any?) = x?.hashCode() ?: 0

    override fun deepCopy(value: Any?): Any {
        if (value != null) {
            return Gson.sharedInstance.fromJson(Gson.sharedInstance.toJson(value), value.javaClass)
        } else {
            throw HibernateException("ERROR: Can not deep copy null")
        }
    }

    override fun replace(original: Any?, target: Any?, owner: Any?) = deepCopy(original)

    override fun equals(x: Any?, y: Any?) = ObjectUtils.nullSafeEquals(x, y)

    override fun returnedClass(): Class<*> = Any::class.java

    override fun assemble(cached: Serializable?, owner: Any?) = deepCopy(cached)

    override fun disassemble(value: Any?) = deepCopy(value) as? Serializable ?: ""

    override fun nullSafeSet(st: PreparedStatement?, value: Any?, index: Int, session: SharedSessionContractImplementor?) {
        if (value == null) {
            st!!.setObject(index, "{}", Types.OTHER)
        } else {
            st!!.setObject(index, Gson.sharedInstance.toJson(value), Types.OTHER)
        }
    }

    override fun nullSafeGet(rs: ResultSet?, names: Array<out String>?, session: SharedSessionContractImplementor?, owner: Any?): Any {
        val rawData = rs!!.getString(names!![0])
        if (owner != null) {
            return Gson.sharedInstance.fromJson(rawData, owner.javaClass.getDeclaredField("data").type)
        } else {
            throw HibernateException("ERROR: Owner container is null")
        }
    }

    override fun isMutable() = true

    override fun sqlTypes() = intArrayOf(Types.JAVA_OBJECT)
}

@TypeDef(name = "JsonbAsGsonType", typeClass = JsonbAsGsonType::class)

@Entity
class Music {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    var id: Long = 0

    @Column(nullable = false)
    @Type(type = "JsonbAsGsonType")
    lateinit var data: MusicData

    ...
}

This custom JPA type convertor can automatically parse or stringify your jsonb data with Gson. Note that in line 52, you muse use a fixed field name of the jsonb field, or you must figure out how to get the jsonb field in JPA ORM model.