https://github.com/ivangfr/spring-data-jpa-relationships

The goal of this project is to study the JPA relationships: one-to-one, one-to-many / many-to-one, and many-to-many.
https://github.com/ivangfr/spring-data-jpa-relationships

java jpa-relationships many-to-many many-to-one mapstruct one-to-many one-to-one postgresql spring-boot spring-data-jpa spring-web-mvc springdoc-openapi testcontainers

Last synced: 6 months ago
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The goal of this project is to study the JPA relationships: one-to-one, one-to-many / many-to-one, and many-to-many.

• Host: GitHub
• URL: https://github.com/ivangfr/spring-data-jpa-relationships
• Owner: ivangfr
• Created: 2023-05-02T21:59:20.000Z (over 2 years ago)
• Default Branch: main
• Last Pushed: 2024-12-17T20:45:10.000Z (10 months ago)
• Last Synced: 2025-03-24T08:42:34.271Z (7 months ago)
• Topics: java, jpa-relationships, many-to-many, many-to-one, mapstruct, one-to-many, one-to-one, postgresql, spring-boot, spring-data-jpa, spring-web-mvc, springdoc-openapi, testcontainers
• Language: Java
• Homepage:
• Size: 313 KB
• Stars: 30
• Watchers: 2
• Forks: 16
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Funding: .github/FUNDING.yml

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README

          
# spring-data-jpa-relationships

The goal of this project is to study the JPA relationships: `one-to-one`, `one-to-many` / `many-to-one`, and `many-to-many`.

## Proof-of-Concepts & Articles

On [ivangfr.github.io](https://ivangfr.github.io), I have compiled my Proof-of-Concepts (PoCs) and articles. You can easily search for the technology you are interested in by using the filter. Who knows, perhaps I have already implemented a PoC or written an article about what you are looking for.

## Additional Readings

- \[**Medium**\] [**Understanding Relationships in JPA: Introduction**](https://medium.com/@ivangfr/understanding-relationships-in-jpa-introduction-5416c8a7c8a9)

- \[**Medium**\] [**Understanding Relationships in JPA: One-to-One with Simple Primary Key**](https://medium.com/@ivangfr/understanding-relationships-in-jpa-one-to-one-with-simple-primary-key-7c32f7e13a6a)

- \[**Medium**\] [**Understanding Relationships in JPA: One-to-One with Shared Primary Key**](https://medium.com/@ivangfr/understanding-relationships-in-jpa-one-to-one-with-shared-primary-key-36596416fe56)

- \[**Medium**\] [**Understanding Relationships in JPA: One-to-Many with Simple Primary Key**](https://medium.com/@ivangfr/understanding-relationships-in-jpa-one-to-many-with-simple-primary-key-e2e975c67c31)

- \[**Medium**\] [**Understanding Relationships in JPA: One-to-Many with Composite Primary Key**](https://medium.com/@ivangfr/understanding-relationships-in-jpa-one-to-many-with-composite-primary-key-1d7724a2bf63)

- \[**Medium**\] [**Understanding Relationships in JPA: Many-to-Many with Simple Primary Key**](https://medium.com/@ivangfr/understanding-relationships-in-jpa-many-to-many-with-simple-primary-key-b38209e5c9b4)

- \[**Medium**\] [**Understanding Relationships in JPA: Many-to-Many with Simple Primary Key and Extra Column**](https://medium.com/@ivangfr/understanding-relationships-in-jpa-many-to-many-with-simple-primary-key-and-extra-column-817e8bdda465)

- \[**Medium**\] [**Understanding Relationships in JPA: Many-to-Many with Composite Primary Key and Extra Column**](https://medium.com/@ivangfr/understanding-relationships-in-jpa-many-to-many-with-composite-primary-key-and-extra-column-a939b107c7cd)

- \[**Medium**\] [**Mastering JPA Relationships: Practical Examples of Bidirectional Associations**](https://medium.com/@ivangfr/spring-data-jpa-6bb5cd745b46)

## Prerequisites

- [`Java 21+`](https://www.oracle.com/java/technologies/downloads/#java21)

- Some containerization tool [`Docker`](https://www.docker.com), [`Podman`](https://podman.io), etc.

## Start Environment

In a terminal and inside the `spring-data-jpa-relationships` root folder, run the following command:

```

docker compose up -d

```

## Running application using Maven

In a terminal and inside the `spring-data-jpa-relationships` root folder, run the command below:

```

./mvnw clean spring-boot:run

```

Once the application is running, you can access its Swagger website at http://localhost:8080/swagger-ui.html.

## Useful Commands

- **Postgres**

  ```

  docker exec -it postgres psql -U postgres -d jparelationshipsdb

  \d persons

  select * from persons;

  ```

  > Type `exit` to exit

## Shutdown

- To stop the application, go to the terminal where it is running and press `Ctrl+C`;

- To stop and remove docker compose containers, network and volumes, go to a terminal and, inside the `spring-data-jpa-relationships` root folder, run the following command:

  ```

  docker compose down -v

  ```

## Running Tests

In a terminal and inside the `spring-data-jpa-relationships` root folder, run the following command:

```

./mvnw clean test

```

## JPA relationships

### One-to-One with Simple Primary Key

![teams_team_details](documentation/teams_team_details.png)

\[**Medium**\]: [**Understanding Relationships in JPA: One-to-One with Simple Primary Key**](https://medium.com/@ivangfr/understanding-relationships-in-jpa-one-to-one-with-simple-primary-key-7c32f7e13a6a)

### One-to-One with Shared Primary Key

![persons_person_details](documentation/persons_person_details.png)

\[**Medium**\] [**Understanding Relationships in JPA: One-to-One with Shared Primary Key**](https://medium.com/@ivangfr/understanding-relationships-in-jpa-one-to-one-with-shared-primary-key-36596416fe56)

### One-to-Many with Simple Primary Key

![restaurants_dishes](documentation/restaurants_dishes.png)

\[**Medium**\] [**Understanding Relationships in JPA: One-to-Many with Simple Primary Key**](https://medium.com/@ivangfr/understanding-relationships-in-jpa-one-to-many-with-simple-primary-key-e2e975c67c31)

### One-to-Many with Composite Primary Key

![players_weapons](documentation/players_weapons.png)

\[**Medium**\] [**Understanding Relationships in JPA: One-to-Many with Composite Primary Key**](https://medium.com/@ivangfr/understanding-relationships-in-jpa-one-to-many-with-composite-primary-key-1d7724a2bf63)

### Many-to-Many with Simple Primary Key

![writers_books](documentation/writers_books.png)

\[**Medium**\] [**Understanding Relationships in JPA: Many-to-Many with Simple Primary Key**](https://medium.com/@ivangfr/understanding-relationships-in-jpa-many-to-many-with-simple-primary-key-b38209e5c9b4)

### Many-to-Many with Simple Primary Key and Extra Column

![reviewers_articles](documentation/reviewers_comments_articles.png)

\[**Medium**\] [**Understanding Relationships in JPA: Many-to-Many with Simple Primary Key and Extra Column**](https://medium.com/@ivangfr/understanding-relationships-in-jpa-many-to-many-with-simple-primary-key-and-extra-column-817e8bdda465)

### Many-to-Many with Composite Primary Key and Extra Column

![students_courses](documentation/students_courses.png)

\[**Medium**\] [**Understanding Relationships in JPA: Many-to-Many with Composite Primary Key and Extra Column**](https://medium.com/@ivangfr/understanding-relationships-in-jpa-many-to-many-with-composite-primary-key-and-extra-column-a939b107c7cd)

## References

One-to-One 

- https://vladmihalcea.com/the-best-way-to-map-a-onetoone-relationship-with-jpa-and-hibernate

- https://www.callicoder.com/hibernate-spring-boot-jpa-one-to-one-mapping-example/

One-to-Many / Many-to-One

- https://vladmihalcea.com/the-best-way-to-map-a-onetomany-association-with-jpa-and-hibernate

- https://www.callicoder.com/hibernate-spring-boot-jpa-one-to-many-mapping-example/

Many-to-Many

- https://vladmihalcea.com/the-best-way-to-use-the-manytomany-annotation-with-jpa-and-hibernate

- https://www.callicoder.com/hibernate-spring-boot-jpa-many-to-many-mapping-example/