jpa h2 connection

Unable to login into H2 Console

1. Are you using >=2.3.0 Release of Spring Boot? You would need to configure this in application.properties.

spring.datasource.url=jdbc:h2:mem:testdb

Why is this needed? With the latest versions of Spring Boot (2.3+), the H2 database name is randomly generated each time you restart the server. We do NOT want that. We want a constant URL.

H2 console available at '/h2-console'. Database available at 'jdbc:h2:mem:dd222195-7e0b-4dc0-ae4c-7f53e5ea7ceb'

1. Make sure you are using jdbc:h2:mem:testdb as the database URL in H2 Console as shown in the image below.

In the browser, change the database url to jdbc:h2:mem:testdb (Shown in the screen below).

1. Do you have H2 dependency in pom.xml? Try removing <scope>runtime</scope> and see if it makes a difference.

<dependency>
	<groupId>com.h2database</groupId>
	<artifactId>h2</artifactId>
</dependency>

1. Check if H2 Console is enabled in application.properties

spring.h2.console.enabled=true

1. Delete your maven local repository (content of .m2 folder) and rebuild the project. (You are right. This looks silly. But do not skip it. I’ve seen many problems caused by dependency caches!)

Tables are not created

Are you using Spring Boot >=2.5.0 Release?

1. Are you using >=2.5.0 Release of Spring Boot? You would need to configure this in application.properties.

spring.jpa.defer-datasource-initialization=true

OR you can use schema.sql instead of data.sql

Why is this needed? https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.5.0-M3-Release-Notes#hibernate-and-datasql => By default, data.sql scripts are now run before Hibernate is initialized. This aligns the behaviour of basic script-based initialization with that of Flyway and Liquibase. If you want to use data.sql to populate a schema created by Hibernate, set spring.jpa.defer-datasource-initialization to true. While mixing database initialization technologies is not recommended, this will also allow you to use a schema.sql script to build upon a Hibernate-created schema before it’s populated via data.sql

No 1 : Are you using Spring Boot >=2.3.0 Release?

Configure this in application.properties

spring.datasource.url=jdbc:h2:mem:testdb
spring.data.jpa.repositories.bootstrap-mode=default

You should see this in the log

H2 console available at '/h2-console'. Database available at 'jdbc:h2:mem:testdb'

Why do we need to configure bootstrap-mode? Details here - https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.3-Release-Notes#bootstrapmode-for-jpa-repositories

No 2 : Make sure you have the right annotations!

Make sure that the Entities have @Entity annotation and the Repository class has @Repository annotation

No 3 : Make sure you do NOT have schema.sql

Delete schema.sql if you have created one.

If schema.sql file exist, tables are NOT created.

No 4 : Make sure your component is picked up by Component Scan

Spring Boot does a component scan in the package and sub-packages where your @SpringBootApplication is defined.

Why is this important? If your entity class or the repository class is NOT under the package of your @SpringBootApplication class, it will NOT be picked up by component scan.

RECOMMENDED OPTION - Option 1 : Move the component under component scan

Simplest way to fix this is to identify the packages of the SpringBootApplication class and move all the components into that package or sub-packages of it.

Option 2 : Add component and entity scan for the packages containing the components

@SpringBootApplication(scanBasePackages= {"com.project.currency.*"})
@EntityScan(basePackages = {"com.project.currency.model"})
@EnableJpaRepositories(basePackages = {"com.project.currency.repository"})

Learn more about component scan:

• https://github.com/in28minutes/in28minutes-initiatives/tree/master/The-in28Minutes-TroubleshootingGuide-And-FAQ#q—what-is-the-need-for-a-component-scan

2.3.0 Course Update

With the latest versions of Spring Boot (2.3+), the H2 database name is randomly generated each time you restart the server.

You can find the database name and URL from the console log.

RECOMMENDED:

Make the database URL a constant by configuring this in application.properties.

spring.datasource.url=jdbc:h2:mem:testdb

If you face any problems:

Spring Boot 2.3.1 Upgrade - Changes

• https://github.com/in28minutes/jpa-with-hibernate/commit/1f30e868ccd2eb7e69cdb989bc990cd00cc82168

JUnit 5 Upgrade - Changes

• https://github.com/in28minutes/jpa-with-hibernate/commit/0ae2007c8e08420e6d5ab2a86499274c7c60c8ae