MongoDB - Lab 3

In this lab, you will create a Java application that utilizes Jakarta Data's repository framework to manage a library of books. The application will allow you to save books, retrieve books by title, and perform pageable queries on the book data.

1. Define the Library Repository Interface

Steps

Create an interface called Library and annotate it with @Repository from the jakarta.data.repository package
```
@Repository
public interface Library {
}
```
Extend the PageableRepository<Book, String> interface, specifying that it's a repository for managing Book entities with String as the type of the ID field
```
@Repository
public interface Library extends PageableRepository<Book, String> {
}
```
Define a custom query method findByTitle() that will take a title as String where the return is a List of Book
```
List<Book> findByTitle(String title);
```

Expected results

Entity Library created

Solution

Click to see...

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

import java.util.List;

@Repository
public interface Library extends PageableRepository<Book, String> {

    List<Book> findByTitle(String title);
}

2. Add a factory data method to `Book`

Steps

Open the Book class

Add the following method

public static Book of(Faker faker) {
    return new Book(faker.code().isbn13(), faker.book().title(), faker.number().numberBetween(1, 10),
        faker.number().numberBetween(1900, 2022));
}

Note

The method of() will take the Faker class that's from the DataFaker library to generate random data when its accessed.

Expected results

Class Book with an additional method to generate its instance using random data

Solution

Click to see...

import com.github.javafaker.Faker;
import jakarta.nosql.Column;
import jakarta.nosql.Entity;
import jakarta.nosql.Id;

@Entity
public record Book(@Id String isbn, @Column String title, @Column int edition, @Column int year) {

    public static Book of(Faker faker) {
        return new Book(faker.code().isbn13(), faker.book().title(), faker.number().numberBetween(1, 10),
            faker.number().numberBetween(1900, 2022));
    }
}

3. Create the execution class to insert data

Steps

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

Add a main method

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

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()) {     
}
```
Using the Jakarta SE container, obtain an instance of the Library repository by selecting it: container.select(Library.class).get()
```
Library library = container.select(Library.class).get();
```
Instantiate the Faker class to be able to, later on, save the book with some data
```
Faker faker = new Faker();
```

Create a look saving 100 different books using the libary.save() method

IntStream.range(0, 100).mapToObj(index -> Book.of(faker)).forEach(library::save);

Create a Pageable object named pageable using Pageable.ofSize(10).sortBy(Sort.asc("title"), Sort.desc("year")). This sets options for retrieving books in pages of size 10, sorted by title in ascending order and year in descending order
- both Pageable and Sort classes are from the jakarta.data.repository package
```
Pageable pageable = Pageable.ofSize(10).sortBy(Sort.asc("title"), Sort.desc("year"));
```
Find all books on the filter we created above, which will contain 10 entries, using the Page class from jakarta.data.repository package
```
Page<Book> page = library.findAll(pageable);
```
Printout the content of the page attribute using the content() method
```
System.out.println("Page = " + page.content());
```
Create a second Pageable object named nextPage to retrieve the next page of books
```
Pageable nextPage = pageable.next();
```

Find all books from the next page

Page<Book> page2 = library.findAll(nextPage);

Printout the content of the page2 attribute using the content() method
```
System.out.println("Page 2 = " + page2);
```
Use the custom query findByTitle() to find the book "Effective Java" and printout the result
```
library.findByTitle("Effective Java").forEach(System.out::println);
```
Define a private constructor for the AppMongoDBPagable class to prevent instantiation since it contains only static methods:
```
private AppMongoDBPagable() {
}
```
Run the main() method

Expected results

The following output

Page = [Book[isbn=2fc4801f-fbed-4878-9e85-538487feae65, title=Effective Java, edition=1, year=2019], Book[isbn=9790753509363, title=If Not Now, When?, edition=5, year=2017], Book[isbn=9780972389006, title=Françoise Sagan, edition=4, year=2016], Book[isbn=9781430782025, title=The Little Foxes, edition=9, year=2012], Book[isbn=9790835585384, title=If Not Now, When?, edition=6, year=2010], Book[isbn=9780771303333, title=The World, the Flesh and the Devil, edition=7, year=2009], Book[isbn=9791077784467, title=To Sail Beyond the Sunset, edition=9, year=2008], Book[isbn=9780705967556, title=That Hideous Strength, edition=3, year=2006], Book[isbn=9790949723771, title=An Instant In The Wind, edition=5, year=2006], Book[isbn=9781470218720, title=The Violent Bear It Away, edition=7, year=2005]]

Page 2 = NoSQLPage{entities=[Book[isbn=9781470218720, title=The Violent Bear It Away, edition=7, year=2005], Book[isbn=9780878082858, title=Where Angels Fear to Tread, edition=3, year=2003], Book[isbn=9791962492460, title=The Moon by Night, edition=4, year=2002], Book[isbn=9780736251754, title=East of Eden, edition=4, year=2002], Book[isbn=9781087074238, title=Nectar in a Sieve, edition=8, year=2001], Book[isbn=9790880353556, title=To Say Nothing of the Dog, edition=4, year=2001], Book[isbn=9781884451362, title=Clouds of Witness, edition=8, year=2000], Book[isbn=9791584073665, title=Have His Carcase, edition=3, year=2000], Book[isbn=9781961487482, title=The Wind's Twelve Quarters, edition=7, year=1999], Book[isbn=9790332536162, title=Edna O'Brien, edition=9, year=1998]], pageable=Pageable{page=2, size=10, title ASC, year DESC}}

Book[isbn=2fc4801f-fbed-4878-9e85-538487feae65, title=Effective Java, edition=1, year=2019]

Solution

Click to see...

import com.github.javafaker.Faker;
import jakarta.data.repository.Page;
import jakarta.data.repository.Pageable;
import jakarta.data.repository.Sort;
import jakarta.enterprise.inject.se.SeContainer;
import jakarta.enterprise.inject.se.SeContainerInitializer;

import java.util.stream.IntStream;

public class AppMongoDBPagable {

    public static void main(String[] args) {

        try (SeContainer container = SeContainerInitializer.newInstance().initialize()) {
            Library library = container.select(Library.class).get();


            Faker faker = new Faker();
            IntStream.range(0, 100).mapToObj(index -> Book.of(faker)).forEach(library::save);

            Pageable pageable = Pageable.ofSize(10).sortBy(Sort.asc("title"), Sort.desc("year"));
            Page<Book> page = library.findAll(pageable);
            System.out.println("Page = " + page.content());

            Pageable nextPage = pageable.next();
            Page<Book> page2 = library.findAll(nextPage);
            System.out.println("Page 2 = " + page2);

            library.findByTitle("Effective Java").forEach(System.out::println);
        }
    }

    private AppMongoDBPagable() {
    }
}

MongoDB - Lab 3

1. Define the Library Repository Interface

Steps

Expected results

Solution

2. Add a factory data method to Book

Steps

Expected results

Solution

3. Create the execution class to insert data

Steps

Expected results

Solution

2. Add a factory data method to `Book`