MongoDB - Lab 4

In this lab, you will create Java classes for defining a repository interface and a main application class. The repository interface (AuthorRepository) will extend PageableRepository for data access, and the main application (App4) will demonstrate how to use this repository to interact with a NoSQL database using Jakarta Data. Below are the step-by-step instructions for creating these classes:

1. Define the AuthorRepository Interface

Steps

1. Create an interface called AuthorRepository in the expert.os.labs.persistence package
2. Annotate it with @Repository from the jakarta.data.repository package

3. Extends the interface with the PageableRepository using the Author class and Long

   @Repository
   public interface AuthorRepository extends PageableRepository<Author, Long> {
   }
   

4. Add a custom query to find the author by name

    List<Author> findByName(String name);
   

5. Add a custom query to find a phone number

   Stream<Author> findByPhones(String phone);
   

Solution

Click to see...

import jakarta.data.repository.PageableRepository;
import jakarta.data.repository.Repository;

import java.util.List;
import java.util.stream.Stream;

@Repository
public interface AuthorRepository extends PageableRepository<Author, Long> {

    List<Author> findByName(String name);

    Stream<Author> findByPhones(String phone);
}

2. Create the execution class

Steps

1. Create a class called AppMongoDBSubdocumentRepository 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 an instance of the AuthorRepository from the Jakarta SE container by selecting it: container.select(AuthorRepository.class).get()

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

10. Use the AuthorRepository to save the Author instance into the NoSQL database

    template.save(author);
    

11. Query the authors by name

    List<Author> authorByName = template.findByName(author.getName());
    

12. Printout the result

    System.out.println("Author by name = " + authorByName);
    

13. Retrieve the same author by it's phone number

    List<Author> list = template.findByPhones(author.getPhones().get(0)).toList();
    

14. Printout the result

    System.out.println("Author's phone = " + list);
    

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

    private AppMongoDBSubdocuments() {
    }
    

16. Run the main() method

Expected results

• The following output

  Author by name = [Author{id=-6736921736259877587, name='Edward Koch', phones=[1-267-083-3844, (367) 346-8130], address=Address{street='Jin Ports', city='North Alysebury'}, job=Job{salary=12.12, occupation='IT Consultant'}}]
  
  Author's phone = [Author{id=-6736921736259877587, name='Edward Koch', phones=[1-267-083-3844, (367) 346-8130], address=Address{street='Jin Ports', city='North Alysebury'}, job=Job{salary=12.12, occupation='IT Consultant'}}]
  

Solution

Click to see...

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

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

public class AppMongoDBSubdocumentRepository {

    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();

            AuthorRepository template = container.select(AuthorRepository.class).get();
            template.save(author);

            List<Author> authorByName = template.findByName(author.getName());
            System.out.println("Author by name = " + authorByName);

            List<Author> list = template.findByPhones(author.getPhones().get(0)).toList();
            System.out.println("Author's phone = " + list);
        }
    }

    private AppMongoDBSubdocumentRepository() {
    }
}