Here, I write how to build application in Spring Boot with DB Migration. I use Kotlin and Harmonica , Kotlin database migration library.
Kotlin 1.3.20
Spring Boot 2.1.2
Harmonica 1.1.17PostgreSQL
IntelliJ IDEA
JDK 11 (You can use JDK 8 or later)
First, let’s generate application base on Spring Initializr .
Choose the following component.
Gradle
Kotlin
Spring Boot 2.1.2
Leave the project meta data as it is.
Add the following dependencies.
Web
PostgreSQL
JPA
Thymeleaf
In old articles, I used kotlinx.html for template, but this time I use Thymeleaf, because most people are familiar with it.
Click “Generate Project” button and extract the zip file, then you can see the file structure as follows.
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demo /
| - build . gradle
| - gradle /
| ` - wrapper /
| | - gradle - wrapper . jar
| ` - gradle - wrapper . properties
| - gradlew
| - gradlew . bat
| - settings . gradle
` - src /
| - main /
| | - kotlin /
| | ` - com /
| | ` - example /
| | ` - demo /
| | ` - DemoApplication . kt
| ` - resources /
| | - application . properties
| | - static /
| ` - templates /
` - test /
` - kotlin /
` - com /
` - example /
` - demo /
` - DemoApplicationTests . kt
Here is the database configuration.
Database name
demo
User name
develoepr
Password
developer
Database port
5432 (Default Port)
If you don’t have PostgreSQL, you can prepare it with docker as follows.
docker run - d - p 5432 : 5432 -- name demo - e POSTGRES_USER = developer - e POSTGRES_PASSWORD = developer - e POSTGRES_DB = sample postgres : 11
If you want to change the listening port, please change the first 5432 to another port number.
From the “File” menu, click “Open”, and choose the file, “settings.gradle“. You will see the dialog that asks whether you open it as a project or not. Then, please click “Open as a Project” button.
After that you will see the dialog for importing, then configure it and click “OK” button.
Well, let’s change the Kotlin version. Open build.gradle and change Kotlin version to 1.3.20.
Let’s add the module. In the Project tool window, choose top directory. From the “File” menu, select “New” and “Module”, the you’ll see “New Module” dialog. On the dialog, please choose “Gradle” in the left pane, and choose “Kotlin (Java)” in the right pane, and click “Next” button.
Next, please configure as follows, and click “Next” button and add the module.
Add as module to
demo
GroupId
com.example (Inherit)
ArtifactId
db
Version
0.0.1-SNAPSHOT (Inherit)
Auto syncronization will work and you may get the following error output.
org . gradle . api . ProjectConfigurationException : A problem occurred configuring project ':db' .
Now, open db/build.gradle and remove the version of the Kotlin plugin and add libraries.
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buildscript {
ext {
kotlinVersion = '1.3.20'
}
repositories {
jcenter ( )
}
dependencies {
classpath group : 'org.jetbrains.kotlin' , name : 'kotlin-script-util' , version : kotlinVersion
classpath 'com.improve_future:harmonica:1.1.17'
}
}
plugins {
id 'org.jetbrains.kotlin.jvm'
}
apply plugin : 'jarmonica'
group 'com.example'
version '0.0.1-SNAPSHOT'
repositories {
mavenCentral ( )
jcenter ( )
}
dependencies {
implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
runtimeOnly 'org.postgresql:postgresql:42.2.5'
implementation 'com.improve_future:harmonica:1.1.17'
implementation group : 'org.reflections' , name : 'reflections' , version : '0.9.11'
}
compileKotlin {
kotlinOptions . jvmTarget = "1.8"
}
compileTestKotlin {
kotlinOptions . jvmTarget = "1.8"
}
Set up the db and directory configuration.
Add the next expression to the bottom of build.gradle.
extensions . extraProperties [ "migrationPackage" ] =
[ project . group , project . rootProject . name , project . name ] . join ( "." )
Next, execute the following command.
mkdir - p db / src / main / kotlin / com / example / demo / db / config
And create file db/src/main/kotlin/com/example/demo/db/config/Default.kt as follows.
package com . example . demo . db
import com . improve_future . harmonica . core . DbConfig
import com . improve_future . harmonica . core . Dbms
config Default : DbConfig ( {
dbms = Dbms . PostgreSQL
dbName = "demo"
host = "127.0.0.1"
user = "developer"
password = "developer"
// Add port configuration if you need
// port = 5432
} )
Now, let’s add the migration. Execute the next command.
. / gradlew jarmonicaCreate - Pname = CreateTask
Then, you can see the file db/src/main/kotlin/com/example/demo/db/migration/Mxxxxxxxxxxxxxxxxxx_CreateTask.kt. Change it as follows.
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package com . example . demo . db . migration
import com . improve_future . harmonica . core . AbstractMigration
/**
* CreateTask
*/
class M20190209141813199_CreateTask : AbstractMigration ( ) {
override fun up ( ) {
createTable ( "task" ) {
varchar ( "name" , size = 200 , nullable = false )
dateTime ( "created_at" , nullable = false )
dateTime ( "updated_at" , nullable = false )
}
}
override fun down ( ) {
dropTable ( "task" )
}
}
Execute migration as follows.
You can see the output like follows.
> Task : db : jarmonicaUp
jdbc : postgresql : //127.0.0.1:5432/demo?autoReconnect=true
== [ Start ] Migrate up 20190209141813199 ==
Create Table : task
== [ End ] Migrate up 20190209141813199 ==
Let’s see the database with psql.
demo = # d
List of relations
Schema | Name | Type | Owner
-- -- -- -- + -- -- -- -- -- -- -- -- -- -- - + -- -- -- -- -- + -- -- -- -- -- -
public | harmonica_migration | table | developer
public | task | table | developer
public | task_id_seq | sequence | developer
( 3 rows )
harmonica_migration table contains the executed migration versions. task table is what we wanted to create and task_id_seq sequence is the sequence for task table, which is created automatically.
demo = # d task
Table "public.task"
Column | Type | Collation | Nullable | Default
-- -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -- -- - + -- -- -- -- -- - + -- -- -- -- -- + -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
id | integer | | not null | nextval ( 'task_id_seq' :: regclass )
name | character varying ( 200 ) | | not null |
created_at | timestamp without time zone | | not null |
Indexes :
"task_pkey" PRIMARY KEY , btree ( id )
task table has id column, which is added automatically, and it uses the sequence.
This article continues to Spring Boot with DB Migration (2 of 2) .
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