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The Complete Guide to Spring 6 and Spring Boot 3

One-to-Many Bidirectional Relationship

Explore how to create and manage a bidirectional one-to-many relationship between Player and Registration entities in Spring Boot using JPA. Understand how to set up entity associations, cascading rules, and controller methods to update these relationships, ensuring proper database mapping and data integrity.

We'll cover the following...

In this lesson we will create a bidirectional one-to-many relationship where a Player can have many Registrations.

Let’s add some real life constraints to the model.

  • Every Registration object must be associated with a Player object.

  • When a Registration object is deleted, the associated Player object should not be deleted.

A bidirectional association between Player and Registration means that we can get all the Registration objects if we have a Player object and vice versa, we can get a Player by using the Registration. Compare this to the unidirectional one-to-many relationship, where we could find the Registration objects given a Tournament but we could not find the Tournament from a Registration object.

Unidirectional relationship between tournament and registration
Unidirectional relationship between tournament and registration

The inverse of one-to-many relationship is many-to-one, where many registrations map to one player.

Many to One relationship: many registrations map to one player
Many to One relationship: many registrations map to one player

For the bidirectional relationship example, create a new package in io.datajek.databaserelationships.onetomany. We will call it bi. Copy the following classes from the onetomany.uni package:

  • DatabaseRelationshipsApplication.java

  • Registration

  • Tournament

Copy the following classes from the onetoone ...