52ndAirhacksQ&A.md

52ndAirhacksQ&A.md

Ask questions and see you at July, 2nd, 6.PM. CET: http://www.ustream.tv/channel/adambien

Also checkout recent episode:

Hello Adam,

Let's say that you are using JAX-RS and you return a Person entity that has a relation with a country.

@Entity
class Person {
    private Long id;
    private String name;
    private Country country;
}

@Entity
class Country {
    private Long id;
    private String name;
}

When i make a GET request on person entity i want to get person's details and only the country ID.
Also on POST requests i want to convert the country ID to the country POJO (country must be received from database).

1. I would like to hear how you would approach this problem.
2. Since i'm using Java EE 8 i tried using JSON-B (JSR 367) to achieve the functionality described above.
   2.1) What's the proper way to inject entity manager on a class that implements the JsonbDeserializer ?
   2.2) Is it possible to make a class that implements the JsonbDeserializer using generics so i wouldn't have to implement JsonbDeserializer for each entity type.

Thank you.

Hi Adam,

I have three questions for the upcoming airhacks show:

1. How do migrate your database schema with Flyway? Do you use the Java/Maven or CLI approach?

What do you think about the following solution (JavaEE 8, OpenLiberty 18.0.0.2, Flyway 5.0.7)?

@Startup
@TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED)
@Singleton
public class FlywayMigration {

    private final Logger log = Logger.getLogger(this.getClass().getName());

    @Resource(lookup = "jdbc/sample")
    DataSource dataSource;

    @PostConstruct
    private void onStartup() {

        if (dataSource == null) {
            log.severe("no datasource found to execute the db migrations!");
            throw new RuntimeException(
                    "no datasource found to execute the db migrations!");
        }

        Flyway flyway = new Flyway();
        flyway.setDataSource(dataSource);
        for (MigrationInfo i : flyway.info().all()) {
            log.info("migrate task: " + i.getVersion() + " : "
                    + i.getDescription() + " from file: " + i.getScript());
        }
        flyway.migrate();

    }
}

And what's your Flyway strategy in enterprise projects for the SQL scripts? Do you create a single SQL script for every change during the Sprint or do you collect all changes during one sprint/cycle and squash them into one single SQL script, so that /db/migration won't grow that much?

2. What are the three most important books about Programming/Software Design/Java every developer should read in your opinion?

3. If you could give your 20-year-old self three lessons for your Developer career, what would it be?

Thank you!