Spring PetClinic Sample Application built with jOOQ

This is a fork of the official Spring PetClinic application with domain & persistence layer built with jOOQ instead of Spring Data JPA.

What is jOOQ?

jOOQ (Java Object Oriented Querying) is a database-mapping library that generates Java code from your database schema and allows you to build type-safe SQL queries through its fluent API. Unlike JPA, which follows an object-first approach, jOOQ takes a SQL-first approach, giving developers precise control over the SQL being executed while maintaining type safety.

jOOQ vs Spring Data JPA

Feature	jOOQ	Spring Data JPA
Approach	SQL-first	Object-first
Code generation	Generates Java code from database schema	Generates database schema from Java entities
Query building	Fluent API for SQL queries	Method names and annotations
SQL control	Precise control over SQL statements	SQL generation handled by ORM
Performance	Better for complex queries	Optimized for basic CRUD operations
Type safety	Compile-time checking of SQL queries	Limited compile-time checking
Learning curve	Steeper for ORM developers	More familiar for Java developers
Caching & state management	No built-in caching or entity state tracking	Built-in caching and entity state management
Verbosity	Very verbose. Queries can be factored.	Very concise for simple CRUD operation
License	Commercial license for some features	Open Source (Apache 2.0)

This Spring Petclinic implementation demonstrates how jOOQ can be used within a Spring Boot application to provide type-safe SQL queries with precise control over database operations.

What are the differences with the original Spring Petclinic?

The main differences with the original Spring Petclinic application are:

• The domain and persistence layer is built using jOOQ instead of Spring Data JPA.
• The pom.xml and build.gradle files are updated to include jOOQ dependencies and plugins. The jooqCodegen plugin is used to generate the Java code from the H2 database schema. You may switch to MySQL or PostgreSQL. See the Database configuration section for more details.
• With JPA, Java records can’t be entities. With jOOQ, we could use some Java records as domain entities. The Vet, Vets, Specialty, PetType and Visit classes has been converted to records. Due to a limitation of the Spring MVC binding, the classes Owner and Pet remain as they are.

Understanding the Spring Petclinic application with a few diagrams

See the presentation here

Run Petclinic locally

Spring Petclinic is a Spring Boot application built using Maven or Gradle. You can build a jar file and run it from the command line (it should work just as well with Java 17 or newer):

git clone https://github.com/spring-petclinic/spring-petclinic-jooq.git
cd spring-petclinic
./mvnw package
java -jar target/*.jar

(On Windows, or if your shell doesn't expand the glob, you might need to specify the JAR file name explicitly on the command line at the end there.)

You can then access the Petclinic at http://localhost:8080/.

Or you can run it from Maven directly using the Spring Boot Maven plugin. If you do this, it will pick up changes that you make in the project immediately (changes to Java source files require a compile as well - most people use an IDE for this):

./mvnw spring-boot:run

NOTE: If you prefer to use Gradle, you can build the app using ./gradlew build and look for the jar file in build/libs.

Building a Container

There is no Dockerfile in this project. You can build a container image (if you have a docker daemon) using the Spring Boot build plugin:

./mvnw spring-boot:build-image

In case you find a bug/suggested improvement for Spring Petclinic

Our issue tracker is available here.

Database configuration

In its default configuration, Petclinic uses an in-memory database (H2) which gets populated at startup with data. The h2 console is exposed at http://localhost:8080/h2-console, and it is possible to inspect the content of the database using the jdbc:h2:mem:<uuid> URL. The UUID is printed at startup to the console.

A similar setup is provided for MySQL and PostgreSQL if a persistent database configuration is needed. Note that whenever the database type changes, the app needs to run with a different profile: spring.profiles.active=mysql for MySQL or spring.profiles.active=postgres for PostgreSQL. See the Spring Boot documentation for more detail on how to set the active profile.

For PostgreSQL, you have to change the defaultNameCase property in the jooqCodegen plugin configuration to lower in the pom.xml or build.gradle file, as PostgreSQL treats unquoted identifiers as lower case by default. This is not necessary for MySQL. Regenerate the jOOQ code after changing the database type by running the jOOQ codegen plugin again:

./mvnw compile org.jooq:jooq-codegen-maven:generate

You can start MySQL or PostgreSQL locally with whatever installer works for your OS or use docker:

docker run -e MYSQL_USER=petclinic -e MYSQL_PASSWORD=petclinic -e MYSQL_ROOT_PASSWORD=root -e MYSQL_DATABASE=petclinic -p 3306:3306 mysql:9.1

or

docker run -e POSTGRES_USER=petclinic -e POSTGRES_PASSWORD=petclinic -e POSTGRES_DB=petclinic -p 5432:5432 postgres:17.0

Further documentation is provided for MySQL and PostgreSQL.

Instead of vanilla docker you can also use the provided docker-compose.yml file to start the database containers. Each one has a service named after the Spring profile:

docker compose up mysql

or

docker compose up postgres

Test Applications

At development time we recommend you use the test applications set up as main() methods in PetClinicIntegrationTests (using the default H2 database and also adding Spring Boot Devtools), MySqlTestApplication and PostgresIntegrationTests. These are set up so that you can run the apps in your IDE to get fast feedback and also run the same classes as integration tests against the respective database. The MySql integration tests use Testcontainers to start the database in a Docker container, and the Postgres tests use Docker Compose to do the same thing.

Compiling the CSS

There is a petclinic.css in src/main/resources/static/resources/css. It was generated from the petclinic.scss source, combined with the Bootstrap library. If you make changes to the scss, or upgrade Bootstrap, you will need to re-compile the CSS resources using the Maven profile "css", i.e. ./mvnw package -P css. There is no build profile for Gradle to compile the CSS.

Working with Petclinic in your IDE

Prerequisites

The following items should be installed in your system:

• Java 17 or newer (full JDK, not a JRE)
• Git command line tool
• Your preferred IDE
  • Eclipse with the m2e plugin. Note: when m2e is available, there is an m2 icon in Help -> About dialog. If m2e is not there, follow the install process here
  • Spring Tools Suite (STS)
  • IntelliJ IDEA
  • VS Code

Steps

1. On the command line run:

   git clone https://github.com/spring-petclinic/spring-petclinic-jooq.git

2. Inside Eclipse or STS:

   Open the project via File -> Import -> Maven -> Existing Maven project, then select the root directory of the cloned repo.

   Then either build on the command line ./mvnw generate-resources or use the Eclipse launcher (right-click on project and Run As -> Maven install) to generate the CSS. Run the application's main method by right-clicking on it and choosing Run As -> Java Application.

3. Inside IntelliJ IDEA:

   In the main menu, choose File -> Open and select the Petclinic pom.xml. Click on the Open button.

   • CSS files are generated from the Maven build. You can build them on the command line ./mvnw generate-resources or right-click on the spring-petclinic project then Maven -> Generates sources and Update Folders.

   • A run configuration named PetClinicApplication should have been created for you if you're using a recent Ultimate version. Otherwise, run the application by right-clicking on the PetClinicApplication main class and choosing Run 'PetClinicApplication'.

4. Navigate to the Petclinic

   Visit http://localhost:8080 in your browser.

Looking for something in particular?

Spring Boot Configuration	Class or Java property files
The Main Class	PetClinicApplication
Properties Files	application.properties
Caching	CacheConfiguration

Interesting Spring Petclinic branches and forks

The Spring Petclinic "main" branch in the spring-projects GitHub org is the "canonical" implementation based on Spring Boot and Thymeleaf. There are quite a few forks in the GitHub org spring-petclinic. If you are interested in using a different technology stack to implement the Pet Clinic, please join the community there.

Interaction with other open-source projects

One of the best parts about working on the Spring Petclinic application is that we have the opportunity to work in direct contact with many Open Source projects. We found bugs/suggested improvements on various topics such as Spring, Spring Data, Bean Validation and even Eclipse! In many cases, they've been fixed/implemented in just a few days. Here is a list of them:

Name	Issue
Spring JDBC: simplify usage of NamedParameterJdbcTemplate	SPR-10256 and SPR-10257
Bean Validation / Hibernate Validator: simplify Maven dependencies and backward compatibility	HV-790 and HV-792
Spring Data: provide more flexibility when working with JPQL queries	DATAJPA-292

Contributing

The issue tracker is the preferred channel for bug reports, feature requests and submitting pull requests.

For pull requests, editor preferences are available in the editor config for easy use in common text editors. Read more and download plugins at https://editorconfig.org. All commits must include a Signed-off-by trailer at the end of each commit message to indicate that the contributor agrees to the Developer Certificate of Origin. For additional details, please refer to the blog post Hello DCO, Goodbye CLA: Simplifying Contributions to Spring.

License

The Spring PetClinic sample application is released under version 2.0 of the Apache License.