MongoDB - Lab 4

In this lab, you will create Java classes that model an Author entity along with related classes for building Author objects, representing addresses, and describing jobs. These classes will be used to interact with a NoSQL database using Jakarta NoSQL and Jakarta EE. Below are the step-by-step instructions for creating these classes

1. Define the Address Embeddable Class

Steps

1. Create a class called Address in the expert.os.labs.persistence package
2. Annotate it using the @Embeddable from the org.eclipse.jnosql.mapping package

3. Add two attributes: city and street and use the @Column annotation, both as String

   @Column
   private String street;
   
   @Column
   private String city;
   

4. Implement constructors, getter methods, equals, hashCode, and toString methods

Solution

Click to see...

import jakarta.nosql.Column;
import org.eclipse.jnosql.mapping.Embeddable;

@Embeddable
public class Address {

    @Column
    private String street;

    @Column
    private String city;

    public Address() {
    }

    public Address(String street, String city) {
        this.street = street;
        this.city = city;
    }

    // other method ignored
}    

2. Define the Job Embeddable Class

Steps

1. Create a class called Job in the expert.os.labs.persistence package
2. Annotate it using the @Embeddable from the org.eclipse.jnosql.mapping package

3. Add two attibutes: salary and occupation and use the @Column annotation, where salary is a double and occupation a String

   @Column
   private double salary;
   
   @Column
   private String occupation;
   

4. Implement constructors, getter methods, equals, hashCode, and toString methods

Solution

Click to see...

import jakarta.nosql.Column;
import org.eclipse.jnosql.mapping.Embeddable;

@Embeddable
public class Job {

    @Column
    private double salary;

    @Column
    private String occupation;

    public Job() {
    }

    public Job(double salary, String occupation) {
        this.salary = salary;
        this.occupation = occupation;
    }

    // other method ignored
}    

3. Define the Author Entity Class

Steps

1. Create a class called Author in the expert.os.labs.persistence package
2. Define the class with the @Entity annotation from the jakarta.nosql package

3. Add the following fields in in the record:

   Annotation	Type	Name
   @Id	Long	id
   @Colum	String	name
   @Colum	List<String>	phones
   @Colum	Address	address
   @Colum	Job	job

4. Implement constructors, getter methods, equals, hashCode, and toString methods

Solution

Click to see...

import jakarta.nosql.Column;
import jakarta.nosql.Entity;
import jakarta.nosql.Id;

import java.util.List;

@Entity
public class Author {

    @Id
    private Long id;

    @Column
    private String name;

    @Column
    private List<String> phones;

    @Column
    private Address address;

    @Column
    private Job job;

    public Author() {
    }

    public Author(Long id, String name, List<String> phones, Address address, Job job) {
        this.id = id;
        this.name = name;
        this.phones = phones;
        this.address = address;
        this.job = job;
    }

    // other method ignored
}  

4. Implement the Builder class

Steps

1. Create a class called AuthorBuilder in the expert.os.labs.persistence package

2. Add the same fields we had previously added to the Author class, without the annotations

   private long id;
   private String name;
   private List<String> phones;
   private Address address;
   private Job job;
   

3. Add the builder methods for each field

4. Add the build() method creating a new instance of Author using its constructor
5. In the Author class add the builder method referring to the AuthorBuilder

Solution

Click to see...

import java.util.List;

public class AuthorBuilder {

    private long id;

    private String name;

    private List<String> phones;

    private Address address;

    private Job job;

    public AuthorBuilder id(long id) {
        this.id = id;
        return this;
    }

    public AuthorBuilder name(String name) {
        this.name = name;
        return this;
    }

    public AuthorBuilder phones(List<String> phones) {
        this.phones = phones;
        return this;
    }

    public AuthorBuilder address(Address address) {
        this.address = address;
        return this;
    }

    public AuthorBuilder job(Job job) {
        this.job = job;
        return this;
    }

    public Author build() {
        return new Author(id, name, phones, address, job);
    }
}

5. Create the execution class

Steps

1. Create a class called AppMongoDBSubdocuments in the expert.os.labs.persistence package

2. Add a main method

   public static void main(String[] args) {
   }
   

3. Create a ThreadLocalRandom instance and get the next value, associating it to an attribute

   ThreadLocalRandom random = ThreadLocalRandom.current();
   long id = random.nextLong();
   

4. Set up a try-with-resources block, inside the main method, to manage the Jakarta EE SeContainer that is responsible for dependency injection and managing resources

   try (SeContainer container = SeContainerInitializer.newInstance().initialize()) {     
   }
   

5. Create a new instance of Faker

   Faker faker = new Faker();
   

6. Create a new instance of the Author class using faker to provide data

   Address address = new Address(faker.address().streetName(), faker.address().city());
   

7. Create a new instance of the Job class using faker to provide data

   Job job = new Job(12.12, faker.job().title());
   

8. Create a new instance of the Author class using faker to provide data

   Author author = Author.builder()
       .phones(Arrays.asList(faker.phoneNumber().cellPhone(), faker.phoneNumber().cellPhone()))
       .name(faker.name().fullName()).address(address).job(job).id(id).build();
   

9. Obtain a DocumentTemplate instance from jakarta.nosql.document package by selecting it: container.select(DocumentTemplate.class).get()

   DocumentTemplate template = container.select(DocumentTemplate.class).get();
   

10. Use the DocumentTemplate to insert the Author instance into the NoSQL database and retrieve the saved author

    Author saved = template.insert(author);
    

11. Printout the saved author

    System.out.println("Author saved = " + saved);
    

12. Use the DocumentTemplate to perform a query to retrieve authors by the city in their address

    List<Author> people = template.select(Author.class).where("address.city").eq(address.getCity()).result();
    

13. Printout the result

    System.out.println("Entities found: " + people);
    

14. Define a private constructor for the AppCassandraOperations class to prevent instantiation since it contains only static methods:

    private AppMongoDBSubdocuments() {
    }
    

15. Run the main() method

Expected results

• The following output

  Author saved = Author{id=-5926041563979906242, name='Marissa Koch Jr.', phones=[347-971-6761, 1-199-518-8887], address=Address{street='Roselee Ports', city='Stantonport'}, job=Job{salary=12.12, occupation='Legal Assistant'}}
  
  Entities found: [Author{id=-5926041563979906242, name='Marissa Koch Jr.', phones=[347-971-6761, 1-199-518-8887], address=Address{street='Roselee Ports', city='Stantonport'}, job=Job{salary=12.12, occupation='Legal Assistant'}}]
  

Solution

Click to see...

import com.github.javafaker.Faker;
import jakarta.enterprise.inject.se.SeContainer;
import jakarta.enterprise.inject.se.SeContainerInitializer;
import jakarta.nosql.document.DocumentTemplate;

import java.util.Arrays;
import java.util.List;
import java.util.concurrent.ThreadLocalRandom;

public class AppMongoDBSubdocuments {

    public static void main(String[] args) {
        ThreadLocalRandom random = ThreadLocalRandom.current();
        long id = random.nextLong();

        try (SeContainer container = SeContainerInitializer.newInstance().initialize()) {
            Faker faker = new Faker();

            Address address = new Address(faker.address().streetName(), faker.address().city());
            Job job = new Job(12.12, faker.job().title());
            Author author = Author.builder()
                .phones(Arrays.asList(faker.phoneNumber().cellPhone(), faker.phoneNumber().cellPhone()))
                .name(faker.name().fullName()).address(address).job(job).id(id).build();

            DocumentTemplate template = container.select(DocumentTemplate.class).get();

            Author saved = template.insert(author);
            System.out.println("Author saved = " + saved);

            List<Author> people = template.select(Author.class).where("address.city").eq(address.getCity()).result();
            System.out.println("Entities found: " + people);
        }
    }

    private AppMongoDBSubdocuments() {
    }
}