application.properties

## Spring DATASOURCE (DataSourceAutoConfiguration & DataSourceProperties)
spring.datasource.url = jdbc:mysql://localhost:3306/sendapi?autoReconnect=true&useUnicode=true&characterEncoding=UTF-8&allowMultiQueries=true&useSSL=false
spring.datasource.username = root
spring.datasource.password = root


## Hibernate Properties

# The SQL dialect makes Hibernate generate better SQL for the chosen database
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL5InnoDBDialect

# Hibernate ddl auto (create, create-drop, validate, update)
spring.jpa.hibernate.ddl-auto = update

Controller

package com.smol.send.api.mvc.controllers

import com.smol.send.api.repositories.MessageRepository
import com.smol.send.api.mvc.models.Message
import org.springframework.web.bind.annotation.*
import javax.validation.Valid


@RestController
@RequestMapping("/api")
class MessageController(private val r : MessageRepository) {

@GetMapping("/messages/{id}")
fun getMessage(@PathVariable("value = id") id:Long,) : Message =
    r.getById(id)

@GetMapping("/messages")
fun getAllMessages() : List<Message> =
    r.findAll()

@PostMapping("/messages")
fun createMessage(@Valid @RequestBody msg : Message) : Message =
    r.save(msg)


}

Entity (Message)

package com.smol.send.api.mvc.models

import org.springframework.stereotype.Component
import javax.persistence.*

//@Component
@Entity
data class Message(
    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
    val id : Long = 0,

    val content: String = ""

) {}

Repository

package com.smol.send.api.repositories

import com.smol.send.api.mvc.models.Message
import org.springframework.data.jpa.repository.JpaRepository
import org.springframework.data.jpa.repository.Query
import org.springframework.stereotype.Repository

@Repository
interface MessageRepository :JpaRepository<Message,Long>
/*
    @Query("select * from MESSAGES")
    fun all() : List<Message>

    @Query("select * from MESSAGES") // where id = ?1
    fun get(id : String) : Message

    //no post fun in Repo
*/

SpringApp

package com.smol.send.api

import org.springframework.boot.autoconfigure.EnableAutoConfiguration
import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.autoconfigure.domain.EntityScan
import org.springframework.boot.runApplication
import org.springframework.context.annotation.ComponentScan

//@EntityScan()
@SpringBootApplication
class SendApiApplication

fun main(args: Array<String>) {
	runApplication<SendApiApplication>(*args)
}