MongoDB - Lab 2

In this lab, you will create a Java application that interacts with a NoSQL database using Jakarta NoSQL and Jakarta EE. The application will define an entity class Book to represent books and use a DocumentTemplate to perform database operations.

1. Define the Book Entity Class

Steps

1. Open the 05-document project and navigate to the src/main/java
2. Create a record called Book in the expert.os.labs.persistence package
3. Define the class with the @Entity annotation from the jakarta.nosql package
4. Add the following fields in the record:
   • @Id String isbn
   • @Column String title
   • @Column int edition
   • @Column int year

Expected results

• Record Book created

Solution

Click to see...

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) {
}

2. Create the execution class to insert data

Steps

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

2. Add a main method

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

3. 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()) {     
   }
   

4. Create an instance of the Book class with some sample data. You can use UUID.randomUUID().toString() for the isbn, "Effective Java" for the title, 1 for the edition, and 2019 for the year. inside the try statement

   Book book = new Book(UUID.randomUUID().toString(), "Effective Java", 1, 2019);
   

5. Obtain a DocumentTemplate instance from the package jakarta.nosql.document using the Jakarta SE container by selecting it: container.select(DocumentTemplate.class).get()

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

6. Use the DocumentTemplate to insert the book instance into the NoSQL database

   Book saved = template.insert(book);
   

7. Printout the content of the book inserted

   System.out.println("Book saved: = " + saved);
   

8. Use the DocumentTemplate to perform a query to retrieve a book by its title

   Optional<Book> bookFound = template.select(Book.class).where("title").eq("Effective Java").singleResult();
   

9. Printout the result

System.out.println("bookFound = " + bookFound);

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

   private AppMongoDB() {
   }
   

2. Run the main() method

Expected results

• The following output

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

Solution

Click to see...

import jakarta.enterprise.inject.se.SeContainer;
import jakarta.enterprise.inject.se.SeContainerInitializer;
import jakarta.nosql.document.DocumentTemplate;

import java.util.Optional;
import java.util.UUID;

public class AppMongoDb {

    public static void main(String[] args) {
        try (SeContainer container = SeContainerInitializer.newInstance().initialize()) {
            Book book = new Book(UUID.randomUUID().toString(), "Effective Java", 1, 2019);

            DocumentTemplate template = container.select(DocumentTemplate.class).get();
            Book saved = template.insert(book);
            System.out.println("Book saved: = " + saved);

            Optional<Book> bookFound = template.select(Book.class).where("title").eq("Effective Java").singleResult();
            System.out.println("Book Found = " + bookFound);
        }
    }

    private AppMongoDb() {
    }
}