1. Overview

In this article, We will learn about Spring boot Flyway Java Based Migration Example. Flyway migration tool provides SQL and Java based migration. In this article, we learn about spring boot SQL based migration example.

• In SQL based migration we can write migration using .SQL file. .SQL will be executed in a sequential manner by Flyway tool. If we require some business logic to migrate existing data then? Here Java based migration will help us.
• In Java based migration will need to create .Java file which implements SpringJdbcMigration interface.

Can we configure JAVA and SQL based migration in the same application? :

Yes. We can configure Java and SQL based migration in same application but we need to take create about file version name.

Steps to configure Java based migration:

1. Create directorysrc/main/java/db/migration directory. In short /db/migration must be available in our classpath.
2. Create Java inside src/main/java/db/migration directory which must be implemented SpringJdbcMigration for spring application, For non-spring application interface is JdbcMigration:

src/main/java/db/migration/V4__Another_user

package db.migration;
import org.flywaydb.core.api.migration.spring.SpringJdbcMigration;
import org.springframework.jdbc.core.JdbcTemplate;
/**
 * Created by JavaDeveloperZone on 12-05-2018.
 */
public class V4__Another_user implements SpringJdbcMigration{
    @Override
    public void migrate(JdbcTemplate jdbcTemplate) throws Exception {
        jdbcTemplate.execute("INSERT INTO employee\n" +
                "(employeeId, employeeName, employeeRole)\n" +
                "VALUES (14, 'Zone', 'ADMN');");
    }
}

Here are rules for the name of a class file. It also available in flyway official document.

Java File Name Rules

NOTE: We can configure same with Spring or Spring MVC Application without Spring boot also. We have used here spring boot to take advantages of configuration.

2. Example

Spring boot Flyway Java Based Migration Example

2.1 pom.xml

We have added flyway-core dependency for flyway.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>spring-boot-example</groupId>
    <artifactId>Spring-boot-flaway-database-migration-example</artifactId>
    <version>1.0-SNAPSHOT</version>
    <description>Spring boot Flyway Java Based Migration Example</description>
    <!-- Inherit defaults from Spring Boot -->
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.8.RELEASE</version>
    </parent>
    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>   <!--It contains database base related classes-->
        </dependency>
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>
        <dependency>
            <groupId>org.flywaydb</groupId>
            <artifactId>flyway-core</artifactId>
            <version>5.0.6</version>
        </dependency>
    </dependencies>
    <!-- Package as an executable jar -->
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

2.2 application.properties

flyway.* are flyway related properties. flyway.url, flyway.user, flyway.password are optional. If we have a separate user for database migration then we can specify using those properties. flyway automatically find the default data source when we will not specify flyway.url, flyway.user, flyway.password.

spring.datasource.url=jdbc:mysql://localhost/demo_database_1
spring.datasource.username=root
spring.datasource.password=
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
debug=true
flyway.baseline-on-migrate=true #used if database has some already table
flyway.enabled=true 
flyway.url=jdbc:mysql://localhost/demo_database_1
flyway.user=root
flyway.password=

2.3 db/migration/V4__Another_user.java

Here we have implements SpringJdbcMigration interface and override migrate() method, Flyway will automatically call migrate() method where we can write our business logic for migration. JdbcTemplate will be passed so we can execute the query using that.

package db.migration;
import org.flywaydb.core.api.migration.spring.SpringJdbcMigration;
import org.springframework.jdbc.core.JdbcTemplate;
/**
 * Created by JavaDeveloperZone on 12-05-2018.
 */
public class V4__Another_user implements SpringJdbcMigration{
    @Override
    public void migrate(JdbcTemplate jdbcTemplate) throws Exception {
        jdbcTemplate.execute("INSERT INTO employee\n" +
                "(employeeId, employeeName, employeeRole)\n" +
                "VALUES (14, 'Zone', 'ADMN');");
    }
}

2.4 resources/db/migration/V1__Create_Employee_Table.sql

CREATE TABLE `employee` (
  `employeeId` int(11) NOT NULL AUTO_INCREMENT,
  `employeeName` varchar(255) DEFAULT NULL,
  `employeeRole` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`employeeId`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=latin1;

2.5 resources/db/migration/V2__Employee_Insert.sql

INSERT INTO employee
(employeeId, employeeName, employeeRole)
VALUES (12, 'Zone', 'ADMN');

2.6 resources/db/migration/V3__Employee_Insert.sql

INSERT INTO employee
(employeeId, employeeName, employeeRole)
VALUES (12, 'Zone', 'ADMN');

2.7 Demo

Let’s run spring boot application:

mvn spring-boot:run

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.5.8.RELEASE)
2018-05-12 16:49:54.895  INFO 115180 --- [           main] o.f.core.internal.util.VersionPrinter    : Flyway Community Edition 5.0.6 by Boxfuse
2018-05-12 16:49:55.161  INFO 115180 --- [           main] o.f.c.internal.database.DatabaseFactory  : Database: jdbc:mysql://localhost/demo_database_1 (MySQL 5.5)
2018-05-12 16:49:55.239  INFO 115180 --- [           main] o.f.core.internal.command.DbValidate     : Successfully validated 4 migrations (execution time 00:00.032s)
2018-05-12 16:49:55.255  INFO 115180 --- [           main] o.f.core.internal.command.DbMigrate      : Current version of schema `demo_database_1`: 3
2018-05-12 16:49:55.255  INFO 115180 --- [           main] o.f.core.internal.command.DbMigrate      : Migrating schema `demo_database_1` to version 4 - Another user

Output:

Spring boot Flyway Java Based Migration Example – Output

3. Concussion

In this article, We have learned about how we can execute Java code with Flyway migration.  Flyway Java Migration Example in spring boot application.

4. References

• Flyway Java Migration Document
• Spring boot flyway example

5. Source Code

spring-boot-Flyway-database-Java-migration-example (47 KB)