TestApp.kt

package org.jetbrains.exposed.spring

import org.jetbrains.exposed.dao.EntityID
import org.jetbrains.exposed.dao.UUIDEntity
import org.jetbrains.exposed.dao.UUIDEntityClass
import org.jetbrains.exposed.dao.UUIDTable
import org.jetbrains.exposed.sql.SchemaUtils
import org.jetbrains.exposed.sql.transactions.transaction
import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication
import org.springframework.context.annotation.Bean
import org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor
import org.springframework.jdbc.datasource.embedded.EmbeddedDatabase
import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseBuilder
import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseType
import org.springframework.transaction.annotation.EnableTransactionManagement
import org.springframework.transaction.annotation.Transactional
import java.util.*
import javax.sql.DataSource


object CustomerTable: UUIDTable(name = "customer") {
    val name = varchar(name = "name", length = 255).uniqueIndex()
}

class CustomerDAO(id: EntityID<UUID>): UUIDEntity(id) {
    companion object : UUIDEntityClass<CustomerDAO>(CustomerTable)

    var name by CustomerTable.name
}

object OrderTable: UUIDTable(name = "orders") {
    val customer = reference(name = "customer_id", foreign = CustomerTable)
    val product = varchar(name = "product", length = 255)
}

class OrderDAO(id: EntityID<UUID>): UUIDEntity(id) {
    companion object : UUIDEntityClass<OrderDAO>(OrderTable)

    var customer by OrderTable.customer
    var product by OrderTable.product
}

open class Service {

    @Transactional
    open fun createCustomer(name: String): CustomerDAO {
        return CustomerDAO.new {
            this.name = name
        }
    }

    @Transactional
    open fun createOrder(customer: CustomerDAO, product: String): OrderDAO {
        return OrderDAO.new {
            this.customer = customer.id
            this.product = product
        }
    }

    @Transactional
    open fun doBoth(name: String, product: String): OrderDAO {
        return createOrder(createCustomer(name), product)
    }

    @Transactional
    open fun findOrderByProduct(product: String) : OrderDAO? {
        return OrderDAO.find { OrderTable.product eq product }.singleOrNull()?.apply {
            this.customer // load to cache
        }
    }

}

@SpringBootApplication
@EnableTransactionManagement
open class App {
    @Bean
    open fun ds(): EmbeddedDatabase = EmbeddedDatabaseBuilder().setName("embeddedTest").setType(EmbeddedDatabaseType.H2).build()

    @Bean
    open fun transactionManager(dataSource: DataSource) = SpringTransactionManager(dataSource)

    @Bean // PersistenceExceptionTranslationPostProcessor with proxyTargetClass=false, see https://github.com/spring-projects/spring-boot/issues/1844
    open fun persistenceExceptionTranslationPostProcessor() = PersistenceExceptionTranslationPostProcessor()

    @Bean
    open fun service() = Service()

}

fun main(args: Array<String>) {

    val app = runApplication<App>(*args)
    val service = app.getBean(Service::class.java)

    transaction {
        SchemaUtils.create(CustomerTable, OrderTable)
    }
    val customer = service.createCustomer("Alice1")
    service.createOrder(customer, "SpringProduct")

    println(service.findOrderByProduct("SpringProduct")?.product)

//    service.doBoth("Bob", "SpringProduct")

}