@OneToMany relationship in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a one-to-many relationship in a Spring Boot entity.

Spring Boot

import jakarta.persistence.*;

@Entity
public class Department {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;

    @[1]
    private List<Employee> employees;

    // getters and setters
}

Drag options to blanks, or click blank then click option'

AOneToOne

BOneToMany

CManyToOne

DManyToMany

Attempts:

3 left

💡 Hint

Common Mistakes

Using @ManyToOne instead of @OneToMany

Using @OneToOne which is for one-to-one relationships

The @OneToMany annotation is used to define a one-to-many relationship from the Department entity to the Employee entity.

2fill in blank

medium

Complete the code to specify the mappedBy attribute in the @OneToMany annotation.

Spring Boot

@OneToMany(mappedBy = "[1]")
private List<Order> orders;

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Acustomer

Border

Corders

Dcustomers

Attempts:

3 left

💡 Hint

Common Mistakes

Using the plural form 'orders' instead of the singular 'customer'

Confusing the owning side field name

The mappedBy attribute refers to the field name in the child entity that owns the relationship. Here, it should be the field in Order that points back to Customer.

3fill in blank

hard

Fix the error in the @OneToMany annotation to enable cascade operations.

Spring Boot

@OneToMany(cascade = CascadeType.[1])
private Set<Item> items;

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ADETACH

BPERSIST

CREFRESH

DALL

Attempts:

3 left

💡 Hint

Common Mistakes

Using only PERSIST or DETACH which limits cascade behavior

Forgetting to add cascade attribute

Using CascadeType.ALL ensures that all cascade operations (persist, merge, remove, refresh, detach) are applied to the related entities.

4fill in blank

hard

Fill both blanks to complete the bidirectional @OneToMany and @ManyToOne relationship.

Spring Boot

public class Parent {

    @OneToMany(mappedBy = "[1]", cascade = CascadeType.ALL)
    private List<Child> children;
}

public class Child {

    @[2]
    private Parent parent;
}

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Aparent

BOneToMany

CManyToOne

Dchildren

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the annotations between Parent and Child

Using wrong field names in mappedBy

The mappedBy in Parent points to the parent field in Child. The Child side uses @ManyToOne to link back to Parent.

5fill in blank

hard

Fill all three blanks to complete the @OneToMany relationship with fetch type and orphan removal.

Spring Boot

@OneToMany(mappedBy = "[1]", fetch = FetchType.[2], orphanRemoval = [3])
private List<Comment> comments;

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Apost

BLAZY

Ctrue

DEAGER

Attempts:

3 left

💡 Hint

Common Mistakes

Using EAGER fetch which loads all data immediately

Setting orphanRemoval to false or missing it

The mappedBy is the field in Comment that points to Post. FetchType.LAZY delays loading until needed. Orphan removal true deletes comments removed from the list.