[FIXED] Hibernate Transient not working in Kotlin

Issue

EDIT: Added the whole stack trace

I have an Class "DGuild" with a couple fields in the Table.
I also have an @Transient field which should not appear in the database table.

But since I added the @Transient annotation it crashes with the following error:

org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
    at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:123)
    at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:77)
    at org.hibernate.metamodel.internal.MetamodelImpl.initialize(MetamodelImpl.java:181)
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:301)
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:469)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:708)
    at eu.dragoncoding.dragonbot.hibernate.HibernateUtils.createSessionFactory(HibernateUtils.kt:75)
    at eu.dragoncoding.dragonbot.hibernate.HibernateUtils.getSessFactory(HibernateUtils.kt:45)
    at eu.dragoncoding.dragonbot.hibernate.HibernateUtils.<clinit>(HibernateUtils.kt:27)
    at eu.dragoncoding.dragonbot.Bot.startUp(Bot.kt:49)
    at eu.dragoncoding.dragonbot.Main.main(Main.kt:19)
Caused by: org.hibernate.InstantiationException: could not instantiate test object : eu.dragoncoding.dragonbot.hibernate.entities.DGuild
    at org.hibernate.engine.internal.UnsavedValueFactory.instantiate(UnsavedValueFactory.java:43)
    at org.hibernate.engine.internal.UnsavedValueFactory.getUnsavedIdentifierValue(UnsavedValueFactory.java:68)
    at org.hibernate.tuple.PropertyFactory.buildIdentifierAttribute(PropertyFactory.java:63)
    at org.hibernate.tuple.entity.EntityMetamodel.<init>(EntityMetamodel.java:140)
    at org.hibernate.persister.entity.AbstractEntityPersister.<init>(AbstractEntityPersister.java:609)
    at org.hibernate.persister.entity.SingleTableEntityPersister.<init>(SingleTableEntityPersister.java:128)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:64)
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481)
    at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:96)
    ... 10 common frames omitted
Caused by: java.lang.reflect.InvocationTargetException: null
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:64)
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:500)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481)
    at org.hibernate.engine.internal.UnsavedValueFactory.instantiate(UnsavedValueFactory.java:40)
    ... 21 common frames omitted
Caused by: java.lang.NullPointerException: null
    at eu.dragoncoding.dragonbot.managers.music.GuildMusicController.<init>(GuildMusicController.kt:14)
    at eu.dragoncoding.dragonbot.hibernate.entities.DGuild.<init>(DGuild.kt:37)
    ... 27 common frames omitted

My class looks like this:

import eu.dragoncoding.dragonbot.defaultChannelID
import eu.dragoncoding.dragonbot.defaultPrefix
import eu.dragoncoding.dragonbot.hibernate.EntityDao
import eu.dragoncoding.dragonbot.managers.GuildManager.removeGuild
import eu.dragoncoding.dragonbot.managers.music.GuildMusicController
import lombok.Data
import lombok.NoArgsConstructor
import org.slf4j.LoggerFactory
import javax.persistence.*

@Entity
@Data
@NoArgsConstructor
@Table(name = "Guilds")

class DGuild: eu.dragoncoding.dragonbot.structures.Entity {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "ID", nullable = false)
    val id: Long = 0

    @Column(name = "guildID", nullable = false)
    var guildID: Long = defaultChannelID
    @Column(name = "prefix", nullable = false)
    var prefix: String = defaultPrefix
    @Column(name = "isJoined", nullable = false)
    var isJoined: Boolean = true
    @Column(name = "botChannelID", nullable = false)
    var botChannelID: Long = defaultChannelID
    @Column(name = "commandsUsed", nullable = false)
    var commandsUsed: Int = 0

    @Transient
    val musicManager: GuildMusicController = GuildMusicController(this)

    constructor(guild_ID: Long) {
        this.guildID = guild_ID
    }
    constructor()

    fun save() {
        EntityDao.save(this)
    }
    fun update() {
        EntityDao.update(this)
    }

    fun activate() {
        if (!isJoined) {
            isJoined = true
            update()
        }
    }
    fun deactivate() {
        if (isJoined) {
            isJoined = false
            update()
            removeGuild(guildID)
        }
    }

    fun incrementCommands() {
        this.commandsUsed += 1
        update()
    }


}

I tried to apply the @Transient to the @field:, the @get: and the @set:
I also made the class a serializable.

When I remove the field and annotation it works fine.

Solution

I made a big mistake at the init...
I provided a null value to a constructor that allowed none.

That happened in the line "val musicManager: GuildMusicController = GuildMusicController(this)" where I wanted to use the DGuild object in the GuildMusicController's constructor. The problem was that it wasn't yet initialized (because it still needed the GuildMusicController object), so it was still null.

Answered By - DragonCoder
Answer Checked By - Senaida (JavaFixing Volunteer)