[Kotlin spring boot] Work with database

pom.xml: add compile plugin

    <build>
        <sourceDirectory>${project.basedir}/src/main/kotlin</sourceDirectory>
        <testSourceDirectory>${project.basedir}/src/test/kotlin</testSourceDirectory>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <plugin>
                <groupId>org.jetbrains.kotlin</groupId>
                <artifactId>kotlin-maven-plugin</artifactId>
                <configuration>
                    <args>
                        <arg>-Xjsr305=strict</arg>
                    </args>
                    <compilerPlugins>
                        <plugin>spring</plugin>
                        <plugin>jpa</plugin>
                    </compilerPlugins>
                </configuration>
                <dependencies>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-allopen</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                    <dependency>
                        <groupId>org.jetbrains.kotlin</groupId>
                        <artifactId>kotlin-maven-noarg</artifactId>
                        <version>${kotlin.version}</version>
                    </dependency>
                </dependencies>
            </plugin>
        </plugins>
    </build>

update application.properties:

spring.datasource.url=jdbc:h2:file:~/theater
spring.datasource.driverClassName = org.h2.Driver
spring.datasource.username = sa
spring.datasource.password =
spring.jpa.properties.hibernate.hbm2dll.auto=update
spring.jpa.hibernate.ddl-auto=create-drop
spring.jpa.properties.hibernate.globally_quoted_identifiers=true

We need to create a jpa interface, so that jpa will help us to generate database table according to our Entity data schema:

data/JPAInterfaces.kt

package com.virtualpairprogrammers.theater.data

import com.virtualpairprogrammers.theater.domain.Seat
import org.springframework.data.jpa.repository.JpaRepository

interface SeatRepository : JpaRepository<Seat, Long>

domain/Seat.kt:

package com.virtualpairprogrammers.theater.domain

import java.math.BigDecimal
import javax.persistence.Entity
import javax.persistence.GeneratedValue
import javax.persistence.GenerationType
import javax.persistence.Id

@Entity
data class Seat(@Id @GeneratedValue(strategy = GenerationType.AUTO)
                val id: Long,
                val row: Char,
                val num: Int,
                val price: BigDecimal,
                val description: String) {
    override fun toString(): String = "Seat $row-$num $$price ($description)"
}

Inside main controller, create a endpoint "bootstrap" when we need to add data into the table

    fun createInitialData(): ModelAndView {
        val seats = theaterService.seats
        seatRepository.saveAll(seats)
        return homePage()
    }

https://github.com/zhentian-wan/kotlin-spring-boot-demo/commit/a1d8bd0925a6189f0aabb351a57cb96a6e81abc8