Скачать или смотреть Resolving Hibernate Validation Issues with Flyway and In-memory H2 Databases in Spring Boot

Learn how to solve Hibernate validation errors when using Flyway migrations with an in-memory H2 database in a Spring Boot application.
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This video is based on the question https://stackoverflow.com/q/72317750/ asked by the user 'Wortig' ( https://stackoverflow.com/u/10524503/ ) and on the answer https://stackoverflow.com/a/72366334/ provided by the user 'Henning' ( https://stackoverflow.com/u/15496965/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction

If you are working on a Spring Boot project that utilizes an in-memory H2 database along with Flyway for database migrations and Hibernate for ORM, you might run into some frustrating issues. One common problem is when Hibernate fails to validate the database schema created by Flyway. This often occurs without any clear reason, leading to confusion as you troubleshoot.

In this guide, we will unravel the mystery behind this issue and provide a clear solution so you can continue developing your application smoothly.

Understanding the Problem

Upon running the application, you might encounter error logs indicating that Hibernate cannot validate the expected tables, despite you having run the Flyway migrations successfully. This typically results in a significant error message stating that a table (like test_entity) is missing.

The main question arises: Is this a problem related to the in-memory H2 database, or is Hibernate connecting to a different database than Flyway?

Steps to Reproduce

To understand how to address this problem, let’s take a quick glance at the setup that leads to the issue:

Creating the Spring Boot Project:

Utilize dependencies for H2, Flyway, and JPA (Hibernate).

Setting Application Properties:

[[See Video to Reveal this Text or Code Snippet]]

Defining an Entity:

[[See Video to Reveal this Text or Code Snippet]]

Creating a Flyway Migration Script:

[[See Video to Reveal this Text or Code Snippet]]

Error Output

When the application runs, you will likely see lengthy logs that culminate in an error, specifically pointing out the missing table as the cause for failure.

The Solution

The solution to this validation issue lies in your properties configuration.

Removing the spring.flyway.url

The crux of the problem can often be traced back to the inclusion of the property spring.flyway.url in your configuration. By removing this property, you allow Spring Boot to handle database connection and configuration automatically.

Why it Works: When you do not set the spring.flyway.url, Spring Boot utilizes either the primary DataSource or the DataSource annotated with @FlywayDataSource. By removing the overridden connection string, Hibernate no longer connects to a closed instance of the H2 database after Flyway completes its migrations.

Explanation of H2 Behavior

The H2 database behaves differently by default when using in-memory configurations. Unless specifically told to keep the database open, connections may close after transactions, which can result in Hibernate connecting to a fresh instance without the tables created during migration.

Conclusion

Using Flyway with Hibernate and in-memory databases can present unique challenges, especially when it comes to configuration. By keeping to Spring Boot’s auto-configuration principles and removing unnecessary properties like spring.flyway.url, you can solve these common validation issues seamlessly.

This simple adjustment in your Spring Boot project could save you hours of frustration, allowing you to focus more on building your application rather than troubleshooting.

Now, get out there and code knowing your configurations are set up for success!