Spring Boot with DB Migration (2 of 2)

Table of Contents

This article is the continuation article of Spring Boot with DB Migration (1 of 2).

Build Application

From now on, create Spring Boot application. Let’s create files in the follwong structure.

demo/
`- src/
`- main/
|- kotlin/
|  `- com/
|     `- example/
|        `- demo/
|           |- domain/
|           |  `- task
|           |     |- Task.kt
|           |     `- TaskRepository.kt
|           |- presentation/
|           |  `- TaskController.kt
|           `- DemoApplication.kt
`- resources/
|- application.properties
`- templates/
`- task/
`- index.html

demo/

`- src/

`- main/

|- kotlin/

| `- com/

| `- example/

| `- demo/

| |- domain/

| | `- task

| | |- Task.kt

| | `- TaskRepository.kt

| |- presentation/

| | `- TaskController.kt

| `- DemoApplication.kt

`- resources/

|- application.properties

`- templates/

`- task/

`- index.html

Add configuration

Update application.properties and DemoApplication class.

Add database configuration to the application.properties.

spring.datasource.url=jdbc:postgresql://localhost:5432/demo
spring.datasource.username=developer
spring.datasource.password=developer
spring.jpa.properties.hibernate.temp.use_jdbc_metadata_defaults=false
spring.jpa.database-platform=org.hibernate.dialect.PostgreSQLDialect

spring.datasource.url=jdbc:postgresql://localhost:5432/demo

spring.datasource.username=developer

spring.datasource.password=developer

spring.jpa.properties.hibernate.temp.use_jdbc_metadata_defaults=false

spring.jpa.database-platform=org.hibernate.dialect.PostgreSQLDialect

Add @EnableJpaAuditing annotation to DemoApplication class. It is used for timestamp auto updating.

package com.example.demo
import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication
import org.springframework.data.jpa.repository.config.EnableJpaAuditing
@SpringBootApplication
@EnableJpaAuditing
class DemoApplication
fun main(args: Array<String>) {
runApplication<DemoApplication>(*args)
}

package com.example.demo

import org.springframework.boot.autoconfigure.SpringBootApplication

import org.springframework.boot.runApplication

import org.springframework.data.jpa.repository.config.EnableJpaAuditing

@SpringBootApplication

@EnableJpaAuditing

class DemoApplication

fun main(args: Array<String>) {

runApplication<DemoApplication>(*args)

}

Entity

Create an entity, which represents the record in the database. Create the file of the class , Task, as domain/task/Task.kt.

package com.example.demo.domain.task
import org.springframework.data.annotation.CreatedDate
import org.springframework.data.annotation.LastModifiedDate
import org.springframework.data.jpa.domain.support.AuditingEntityListener
import java.util.*
import javax.persistence.*
@Entity
@EntityListeners(AuditingEntityListener::class)
class Task {
@Id
@SequenceGenerator(
name = "task_id_seq",
sequenceName = "task_id_seq",
allocationSize = 1
)
@GeneratedValue(
strategy = GenerationType.SEQUENCE,
generator = "task_id_seq"
)
var id: Long? = null
var name: String? = null
@CreatedDate
@Temporal(TemporalType.TIMESTAMP)
@Column(nullable = false, updatable = false)
var createdAt: Date? = null
@LastModifiedDate
@Temporal(TemporalType.TIMESTAMP)
@Column(nullable = false, updatable = false)
var updatedAt: Date? = null
}

package com.example.demo.domain.task

import org.springframework.data.annotation.CreatedDate

import org.springframework.data.annotation.LastModifiedDate

import org.springframework.data.jpa.domain.support.AuditingEntityListener

import java.util.*

import javax.persistence.*

@Entity

@EntityListeners(AuditingEntityListener::class)

class Task {

@Id

@SequenceGenerator(

name = "task_id_seq",

sequenceName = "task_id_seq",

allocationSize = 1

)

@GeneratedValue(

strategy = GenerationType.SEQUENCE,

generator = "task_id_seq"

)

var id: Long? = null

var name: String? = null

@CreatedDate

@Temporal(TemporalType.TIMESTAMP)

@Column(nullable = false, updatable = false)

var createdAt: Date? = null

@LastModifiedDate

@Temporal(TemporalType.TIMESTAMP)

@Column(nullable = false, updatable = false)

var updatedAt: Date? = null

}

@EntityListeners, @CreateDate and @LastModifiedDate are added for auto updating.

Repository

Create the repository interface, TaskRepository, for Task, as domain/task/TaskRepository.kt.

package com.example.demo.domain.task
import org.springframework.data.jpa.repository.JpaRepository
interface TaskRepository : JpaRepository<Task, Long>

package com.example.demo.domain.task

import org.springframework.data.jpa.repository.JpaRepository

interface TaskRepository : JpaRepository<Task, Long>

View template

Create the view template, which is resources/templates/task/index.html.

<!DOCTYPE html>
<html lang="ja" xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<meta name="viewport"
content="width=device-width, initial-scale=1.0">
<title>Sample Application</title>
<link rel="stylesheet"
href="https://stackpath.bootstrapcdn.com/bootst
rap/4.1.3/css/bootstrap.min.css"
crossorigin="anonymous">
</head>
<body>
<header class="pos-f-t mb-2">
<nav class="navbar navbar-light bg-light">
<a th:href="@{/task}" class="navbar-brand">
Task List
</a>
</nav>
</header>
<main class="container">
<div class="row" th:if="${success}">
<div class="col">
<div class="alert alert-success"
role="alert"
th:text="${success}"></div>
</div>
</div>
<div class="row" th:each="task : ${taskList}">
<div class="col">
<div class="d-flex">
<div class="p-2 w-100 align-self-center"
th:text="${task.name}">
</div>
<div class="p-2 flex-shrink-1 align-self-center">
<form th:object="${task}"
th:action="@{/task/{id}(id=${task.id})}"
th:method="delete">
<button class="btn btn-outline-danger btn-sm"
type="submit">
X
</button>
</form>
</div>
</div>
</div>
</div>
<hr>
<div class="row">
<div class="col">
<form th:method="post"
th:action="@{/task}"
th:object="${newTask}">
<div class="form-group">
<input type="text"
name="name"
class="form-control"
th:field="*{name}">
</div>
<div class="form-group">
<button class="btn btn-primary btn-block"
type="submit">
Submit
</button>
</div>
</form>
</div>
</div>
</main>
</body>
</html>

<!DOCTYPE html>

<head>

content="width=device-width, initial-scale=1.0">

<title>Sample Application</title>

href="https://stackpath.bootstrapcdn.com/bootst

rap/4.1.3/css/bootstrap.min.css"

crossorigin="anonymous">

</head>

<body>

Task List

</a>

</nav>

</header>

<div class="alert alert-success"

role="alert"

th:text="${success}"></div>

</div>

<div class="p-2 w-100 align-self-center"

th:text="${task.name}">

</div>

<form th:object="${task}"

th:action="@{/task/{id}(id=${task.id})}"

th:method="delete">

<button class="btn btn-outline-danger btn-sm"

type="submit">

</button>

</form>

</div>

<hr>

<form th:method="post"

th:action="@{/task}"

th:object="${newTask}">

<input type="text"

name="name"

class="form-control"

th:field="*{name}">

</div>

<button class="btn btn-primary btn-block"

type="submit">

Submit

</button>

</div>

</form>

</div>

</main>

</body>

</html>

Controller

Create the controller, TaskController, as presentation/task/TaskController.kt.

package com.example.demo.presentation.task
import com.example.demo.domain.task.Task
import com.example.demo.domain.task.TaskRepository
import org.springframework.data.domain.Sort
import org.springframework.stereotype.Controller
import org.springframework.ui.ModelMap
import org.springframework.web.bind.annotation.*
import org.springframework.web.servlet.mvc.support.RedirectAttributes
@Controller
@RequestMapping("task")
class TaskController(
private val taskRepository: TaskRepository
) {
@GetMapping
fun list(modelMap: ModelMap): String {
modelMap["taskList"] =
taskRepository.findAll(
Sort.by("id").descending()
)
modelMap["newTask"] = Task()
return "task/index"
}
@PostMapping
fun create(
attributes: RedirectAttributes,
@ModelAttribute task: Task
): String {
taskRepository.save(task)
attributes.addFlashAttribute(
"success", "The Task was successfully created."
)
return "redirect:/task"
}
@DeleteMapping("{id}")
fun delete(
attributes: RedirectAttributes,
@PathVariable id: Long
): String {
taskRepository.deleteById(id)
attributes.addFlashAttribute(
"success", "The Task was successfully deleted."
)
return "redirect:/task"
}
}

package com.example.demo.presentation.task

import com.example.demo.domain.task.Task

import com.example.demo.domain.task.TaskRepository

import org.springframework.data.domain.Sort

import org.springframework.stereotype.Controller

import org.springframework.ui.ModelMap

import org.springframework.web.bind.annotation.*

import org.springframework.web.servlet.mvc.support.RedirectAttributes

@Controller

@RequestMapping("task")

class TaskController(

private val taskRepository: TaskRepository

) {

@GetMapping

fun list(modelMap: ModelMap): String {

modelMap["taskList"] =

taskRepository.findAll(

Sort.by("id").descending()

)

modelMap["newTask"] = Task()

return "task/index"

}

@PostMapping

fun create(

attributes: RedirectAttributes,

@ModelAttribute task: Task

): String {

taskRepository.save(task)

attributes.addFlashAttribute(

"success", "The Task was successfully created."

)

return "redirect:/task"

}

@DeleteMapping("{id}")

fun delete(

attributes: RedirectAttributes,

@PathVariable id: Long

): String {

taskRepository.deleteById(id)

attributes.addFlashAttribute(

"success", "The Task was successfully deleted."

)

return "redirect:/task"

}

Run the application

Execute ./gradlew bootrun, and after awhile, you can see the page on the browser. Please access to http://localhost:8080/task. And you can add and remove tasks.