This tutorial will walk you through the steps of creating an example on handling circular references/dependencies of JPA and Hibernate entity bidirectional relationships with Jackson JsonIgnoreProperties, CRUD RESTful APIs, Spring Data REST, MySQL, and Docker.
In practice, you may also like to handle the JPA and Hibernate circular references/dependencies problem with the DTO design pattern. Check out the following tutorial as one of the approaches MapStruct Example of Mapping JPA/Hibernate Entity with DTO
What you'll need
- JDK 8+ or OpenJDK 8+
- Maven 3+
- MySQL Server 5+ or Docker CE 18+
Init project structure and dependencies
Project structure
├── src
│ └── main
│ ├── java
│ │ └── com
│ │ └── hellokoding
│ │ ├── jpa
│ │ │ ├── book
│ │ │ │ ├── Author.java
│ │ │ │ ├── AuthorRepository.java
│ │ │ │ ├── Book.java
│ │ │ │ ├── BookPublisher.java
│ │ │ │ ├── BookPublisherRepository.java
│ │ │ │ ├── BookRepository.java
│ │ │ │ ├── Category.java
│ │ │ │ ├── CategoryRepository.java
│ │ │ │ ├── Publisher.java
│ │ │ │ └── PublisherRepository.java
│ │ │ └── JpaApplication.java
│ │ └── springboot
│ └── resources
│ └── application.properties
├── Dockerfile
├── docker-compose.yml
└── pom.xml
Project dependencies
Define JPA Entities Bidirectional Relationships with Jackson circular references handling
Jackson @JsonIgnoreProperties will prevent specified fields from being serialized or deserialized.
Lombok @EqualsAndHashCode with exclude will ignore specified fields on the generated equals and hashCode function of Lombok @Data
Define Repositories
Spring Data REST will auto create RESTful APIs based on your domain model and repository.
Config and Run
Application Configurations
Run with JDK/OpenJDK and Maven
Type the below command at the project root directory
mvn clean spring-boot:run
Test circular references handling and RESTful APIs with curl
Create a new book
curl -i -X POST -H "Content-Type:application/json" -d "{\"title\" : \"Hello Koding\", \"description\": \"Simple coding examples and tutorials\"}" http://localhost:8080/books
Create a new author
curl -i -X POST -H "Content-Type:application/json" -d "{\"name\":\"Author 1\"}" http://localhost:8080/authors
Assign the author to the book
curl -i -X PUT -H "Content-Type:text/uri-list" -d "http://localhost:8080/authors/1" http://localhost:8080/books/1/authors
Find all books
curl http://localhost:8080/books
Find authors of book id 1
curl http://localhost:8080/books/1/authors
Find books of author id 1
curl http://localhost:8080/authors/1/books
