Kotlin: Database Migration – Harmonica 1.0.10

Table of Contents

Here, I announce the new release of Harmonica, Kotlin database migration library. The version is 1.0.10.

In this article, gradlew command is written in Unix style but this tool can also be used in Windows OS. Of course I checked in Windows.

New Main Feature

It can be used for MySQL, too.

Before, it is not completely tested for MySQL. But now, it was tested and it can be used.

Decimal column is intoroduced.

Before, it can’t handle decimal column completely. Now we can use decimal column with precision and scale.

addColumn function.

addColumn function is introduced.

Seze of VARCHAR can be set.

Before, it couldn’t be set.

step parameter is introduced.

Before, jarmonicaUp executes all remain migrations and jarmonicaDown reverts only one migration. But now, step parameter can be used as follows and control migration more flexibly.

./gradlew jarmonicaUp -Pstep=2
./gradlew jarmonicaDown -Pstep=2

1 2	./gradlew jarmonicaUp -Pstep=2 ./gradlew jarmonicaDown -Pstep=2

NOT NULL constraint can be added.

NOT NULL constraint can be added as follows.

override fun up() {
createTable("not_null_name") {
integer("integer_column", nullable = false)
varchar("varchar_column", nullable = false)
decimal("decimal_column", nullable = false)
text("text_column", nullable = false)
}
}

override fun up() {

createTable("not_null_name") {

integer("integer_column", nullable = false)

varchar("varchar_column", nullable = false)

decimal("decimal_column", nullable = false)

text("text_column", nullable = false)

}

DEFAULT keyword can be used.

DEFAULT keyword can be used as follows.

override fun up() {
createTable("default_table") {
integer("integer_column", default = 1)
varchar("varchar_column", default = "text")
decimal("decimal_column", default = 1.1)
text("text_column", default = "text")
}
}

override fun up() {

createTable("default_table") {

integer("integer_column", default = 1)

varchar("varchar_column", default = "text")

decimal("decimal_column", default = 1.1)

text("text_column", default = "text")

}

Fix migration package in the migration jarmonicaCreate creates.

Before, jarmonicaCreate creates migration file without package description and it can’t be executed by jarmonicaUp as it is.. Now, jarmonicaCreate insert package description into new migration and jarmonicaUp can use its package.

And there are some bug fixes.

How to Use

I will explain required configuration. Harmonica Test can be other example.

Set up build.gradle

Set up build.gradle as follows.

buildscript {
ext.kotlin_version = '1.2.51'
ext.harmonica_version = '1.0.10'
repositories {
jcenter()
mavenCentral()
maven { url 'https://jitpack.io' }
}
dependencies {
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
// required for plugin
classpath "com.github.KenjiOhtsuka:harmonica:$harmonica_version"
}
}
group 'com.improve_future'
version ext.harmonica_version
apply plugin: 'kotlin'
// required for gradle commands
apply plugin: 'jarmonica'
// Default value is src/main/kotlin/db
extensions.extraProperties["directoryPath"] =
"src/main/kotlin/com/improve_future/harmonica_test/jarmonica"
// Default value is db
extensions.extraProperties["migrationPackage"] =
"com.improve_future.harmonica_test.jarmonica"
sourceCompatibility = 1.8
repositories {
mavenCentral()
// required
maven { url 'https://jitpack.io' }
}
dependencies {
compile "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin
_version"    
// required
compile group: 'org.reflections', name: 'reflections', version: '0.9.11'
compile group: 'org.jetbrains.kotlin', name: 'kotlin-script-runtime', version: kotlin_version
compile group: 'org.jetbrains.kotlin', name: 'kotlin-script-util', version: kotlin_version
compile group: 'org.jetbrains.kotlin', name: 'kotlin-reflect', version: kotlin_version
// JDBC Driver (MySQL or PostgreSQL), prepare for your DBMS
compile files('/lib/postgresql-42.2.2.jar')
compile files('/lib/mysql-connector-java-8.0.11.jar')
//required
compile "com.github.KenjiOhtsuka:harmonica:$harmonica_version"
}

buildscript {

ext.kotlin_version = '1.2.51'

ext.harmonica_version = '1.0.10'

repositories {

jcenter()

mavenCentral()

maven { url 'https://jitpack.io' }

}

dependencies {

classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"

// required for plugin

classpath "com.github.KenjiOhtsuka:harmonica:$harmonica_version"

}

group 'com.improve_future'

version ext.harmonica_version

apply plugin: 'kotlin'

// required for gradle commands

apply plugin: 'jarmonica'

// Default value is src/main/kotlin/db

extensions.extraProperties["directoryPath"] =

"src/main/kotlin/com/improve_future/harmonica_test/jarmonica"

// Default value is db

extensions.extraProperties["migrationPackage"] =

"com.improve_future.harmonica_test.jarmonica"

sourceCompatibility = 1.8

repositories {

mavenCentral()

// required

maven { url 'https://jitpack.io' }

}

dependencies {

compile "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin

_version"

// required

compile group: 'org.reflections', name: 'reflections', version: '0.9.11'

compile group: 'org.jetbrains.kotlin', name: 'kotlin-script-runtime', version: kotlin_version

compile group: 'org.jetbrains.kotlin', name: 'kotlin-script-util', version: kotlin_version

compile group: 'org.jetbrains.kotlin', name: 'kotlin-reflect', version: kotlin_version

// JDBC Driver (MySQL or PostgreSQL), prepare for your DBMS

compile files('/lib/postgresql-42.2.2.jar')

compile files('/lib/mysql-connector-java-8.0.11.jar')

//required

compile "com.github.KenjiOhtsuka:harmonica:$harmonica_version"

}

Some package such as “org.reflections.reflections” are required. In addition, you can use Exposed if you want.

Directory Structure

Set up directory structure.

`- src
`- main
`- kotlin
`- db
|- config
| |- Default.kt <- default configuration file
| `- OtherEnvironment.kt < you can use other environment
`- migration

`- src

`- main

`- kotlin

`- db

|- config

| |- Default.kt <- default configuration file

| `- OtherEnvironment.kt < you can use other environment

`- migration

Configuration File

Default.kt and other environment configuration file must be as follows.

package db.config
import com.improve_future.harmonica.core.DbConfig
import com.improve_future.harmonica.core.Dbms
class Default: DbConfig({
dbms = Dbms.PostgreSQL
user = "developer"
password = "developer"
host = "127.0.0.1"
dbName = "harmonica_test"
})

package db.config

import com.improve_future.harmonica.core.DbConfig

import com.improve_future.harmonica.core.Dbms

class Default: DbConfig({

dbms = Dbms.PostgreSQL

user = "developer"

password = "developer"

host = "127.0.0.1"

dbName = "harmonica_test"

})

If you want to use other database configuration file, use env parameter with Harmonica command (-Penv=OtherEnvironment).

Create Migration

You can create new migration with the following command.

./gradlew jarmonicaCreate

1	./gradlew jarmonicaCreate

If you want to specify the migration name, use migrationName property.

./gradlew jarmonicaCreate -PmigrationName=HelloWorld

1	./gradlew jarmonicaCreate -PmigrationName=HelloWorld

Then you can get the following file.

package db.migration
import com.improve_future.harmonica.core.AbstractMigration
/**
* HolloWorld
*/
class M20180624011127699_HolloWorld : AbstractMigration() {
override fun up() {
createTable("table_name") {
integer("column_1")
varchar("column_2")
}
}
override fun down() {
dropTable("table_name")
}
}

package db.migration

import com.improve_future.harmonica.core.AbstractMigration

/**

* HolloWorld

class M20180624011127699_HolloWorld : AbstractMigration() {

override fun up() {

createTable("table_name") {

integer("column_1")

varchar("column_2")

}

override fun down() {

dropTable("table_name")

}

Migrate Up or Down

Up

Migrate up with the command.

./gradlew jarmonicaUp

1	./gradlew jarmonicaUp

As default, all migration which are not executed will be executed. If you want to specify the number of migrations to be executed, use step parameter.

./gradlew jarmonicaUp -Pstep=2

1	./gradlew jarmonicaUp -Pstep=2

Down

If you want to revert migration, migrate down with the command.

./gradlew jarmonicaUp

1	./gradlew jarmonicaUp

As default, only one migration will be reverted. If you want to specify the number of migrations to be reverted, use step parameter.

./gradlew jarmonicaUp -Pstep=2

1	./gradlew jarmonicaUp -Pstep=2

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Kotlin: Database Migration – Harmonica

The Life

Kotlin: Database Migration – Harmonica 1.0.10

New Main Feature

How to Use

Set up build.gradle

Directory Structure

Configuration File

Create Migration

Migrate Up or Down

Up

Down

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