@OneToMany relationship in Spring Boot - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the @OneToMany annotation represent in Spring Boot?

It represents a relationship where one entity is linked to many instances of another entity, like one author having many books.

intermediate

In a @OneToMany relationship, which side owns the relationship by default?

The "many" side owns the relationship by default, meaning it holds the foreign key in the database.

intermediate

How do you specify the field that owns the relationship in a @OneToMany mapping?

You use the 'mappedBy' attribute on the @OneToMany annotation to point to the owning field on the 'many' side.

intermediate

What is the effect of using CascadeType.ALL in a @OneToMany relationship?

It means that operations like save, update, or delete on the parent entity will automatically apply to the related child entities.

beginner

Why is it important to use a collection type like List or Set in a @OneToMany relationship?

Because one entity relates to many others, a collection holds all related entities, allowing easy access and management.

What annotation is used on the 'one' side to define a one-to-many relationship?

A @OneToMany

B @ManyToOne

C @ManyToMany

D @OneToOne

The @OneToMany annotation defines the 'one' side of a one-to-many relationship.

Which attribute tells JPA which field owns the relationship in @OneToMany?

A cascade

B targetEntity

C mappedBy

D fetch

The 'mappedBy' attribute points to the owning field on the 'many' side.

If you want changes in the parent entity to affect child entities automatically, which CascadeType should you use?

A CascadeType.ALL

B CascadeType.MERGE

C CascadeType.NONE

D CascadeType.DETACH

CascadeType.ALL applies all operations like save, update, and delete to child entities.

In a @OneToMany relationship, where is the foreign key stored?

A In the 'one' side table

B No foreign key is used

C In a join table

D In the 'many' side table

The foreign key is stored in the 'many' side table pointing back to the 'one' side.

Which Java collection is commonly used to hold related entities in a @OneToMany relationship?

A Map

B List

C Queue

D Stack

List or Set are commonly used to hold multiple related entities.

Explain how the @OneToMany annotation works in Spring Boot and how it connects two entities.

Think about how one author can have many books and how the database knows this.

Describe the role of cascade types in a @OneToMany relationship and why they are useful.

Imagine deleting an author and wanting all their books deleted automatically.