spring-boot-graphql

type Person {
    id: ID
    name: String!
    contact: Contact
}

type Query {
    countPersons: Long!
    findByName(name: String!): [Person]!
    findAllPerson: [Person]!
}

type Contact {
    id: ID
    emailId: String
    mobileNumber: String!
}

extend type Query {
    findAllContact: [Contact]!
    countContacts: Long!
    findByMobileNumber(mobileNumber: String!): [Contact]!
    findByEmailId(emailId: String!): [Contact]!
}

@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder
@Entity
@Table(name = "persons")
public class Person extends BaseAbstractEntity {

    @Column(name="person_name", nullable = false)
    private String name;

    @OneToOne(fetch = javax.persistence.FetchType.LAZY)
    @JoinColumn(name = "contact_id", referencedColumnName = "id")
    private Contact contact;

}

@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder
@Entity
@Table(name = "contacts")
public class Contact extends BaseAbstractEntity {

    @Column(name="contact_email_id")
    private String emailId;

    @Column(name="contact_mobile_number", nullable = false)
    private String mobileNumber;

    @OneToOne(mappedBy = "contact")
    private Person person;

}

public class Query implements GraphQLQueryResolver {

    private final PersonRepository personRepository;
    private final ContactRepository contactRepository;

    public Query(PersonRepository personRepository, ContactRepository contactRepository) {
        this.personRepository = personRepository;
        this.contactRepository = contactRepository;
    }

    public Iterable findAllPerson() {
        return personRepository.findAll();
    }
}