/user-guide-code-samples

Here are the code samples used in the Speedment User's Guide

Primary LanguageJava

Speedment Examples

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This module shows basic examples of how to use Speedment including standard problems solving such as many-to-many, paging etc.

Requirements

The examples make use of the "sakila" example database available directly from Oracle here. Download and install the database content on your target machine before running any of the examples.

Table of Contents

  1. Query with Optimised Stream Predicate Short-Circuit
  2. Query with Optimised Paging
  3. Classification
  4. Joins
  5. One-to-many
  6. Many-to-one
  7. Many-to-many
  8. Entities are Linked
  9. Easy Initialization
  10. Easy Persistence
  11. Update
  12. Remove
  13. Transactions
  14. Full Transparancy
  15. Integration with Spring Boot

Query with Optimised Stream Predicate Short-Circuit

Search for a long film (of length greater than 120 minutes):

// Searches are optimized in the background!
Optional<Film> longFilm = films.stream()
    .filter(Film.LENGTH.greaterThan(120))
    .findAny();

Results in the following SQL query:

SELECT 
    `film_id`,`title`,`description`,`release_year`,
    `language_id`,`original_language_id`,`rental_duration`,`rental_rate`,
    `length`,`replacement_cost`,`rating`,`special_features`,
    `last_update` 
FROM 
     `sakila`.`film
WHERE
    (`length` > 120)

Query with Optimised Paging

Show page 3 of PG-13 rated films sorted by length:

private static final long PAGE_SIZE = 50;

// Even complex streams can be optimized!
long page = 3;
List<Film> stream = films.stream()
    .filter(Film.RATING.equal("PG-13"))
    .sorted(Film.LENGTH)
    .skip(page * PAGE_SIZE)
    .limit(PAGE_SIZE)
    .collect(toList());

Results in the following SQL query:

SELECT 
    `film_id`,`title`,`description`,`release_year`,
    `language_id`,`original_language_id`,`rental_duration`,`rental_rate`,
    `length`,`replacement_cost`,`rating`,`special_features`,
    `last_update` 
FROM 
    `sakila`.`film` 
WHERE 
    (`rating`  = 'PG-13' COLLATE utf8_bin) 
ORDER BY 
    `sakila`.`film`.`length` ASC 
LIMIT 50 OFFSET 150;

Classification

Create a Map with film ratings and the corresponding films:

Map<String, List<Film>> map = films.stream()
    .collect(
        Collectors.groupingBy(
            // Apply this classifier
            Film.RATING
        )
    );

This will produce a Map like this:

Rating PG-13 maps to 223 films 
Rating R     maps to 195 films 
Rating NC-17 maps to 210 films 
Rating G     maps to 178 films 
Rating PG    maps to 194 films

Joins

Define a Join relation:

Join<Tuple2<Film, Language>> join = joinComponent
    .from(FilmManager.IDENTIFIER)
    .innerJoinOn(Language.LANGUAGE_ID).equal(Film.LANGUAGE_ID)
    .build(Tuples::of);

Apply that join relation and print all films and their corresponding language:

join.stream()
    .map(t2 -> String.format("The film '%s' is in %s", t2.get0().getTitle(), t2.get1().getName()))
    .forEach(System.out::println);

Apply that join relation and construct a Map with all languages and their corresponding films:

Map<Language, List<Tuple2<Film, Language>>> languageFilmMap = join.stream()
    .collect(
        // Apply this classifier
        groupingBy(Tuple2::get1)
    );

One-to-many

Print all Languages and their corresponding Films (A specific language can be spoken in many films):

Join<Tuple2<Language, Film>> join = joinComponent
    .from(LanguageManager.IDENTIFIER)
    .innerJoinOn(Film.LANGUAGE_ID).equal(Language.LANGUAGE_ID)
    .build(Tuples::of);

join.stream()
    .forEach(System.out::println);

Many-to-one

Print all Films and their corresponding Languages (A Film can only have one language):

Join<Tuple2<Film, Language>> join = joinComponent
    .from(FilmManager.IDENTIFIER)
    .innerJoinOn(Language.LANGUAGE_ID).equal(Film.LANGUAGE_ID)
    .build(Tuples::of);

join.stream()
    .forEach(System.out::println);

Many-to-many

Construct a Map with all Actors and the corresponding Films they have acted in:

Join<Tuple3<FilmActor, Film, Actor>> join = joinComponent
    .from(FilmActorManager.IDENTIFIER)
    .innerJoinOn(Film.FILM_ID).equal(FilmActor.FILM_ID)
    .innerJoinOn(Actor.ACTOR_ID).equal(FilmActor.ACTOR_ID)
    .build(Tuples::of);
    
Map<Actor, List<Film>> filmographies = join.stream()
    .collect(
        groupingBy(Tuple3::get2, // Applies Actor as classifier
            mapping(
                Tuple3::get1, // Extracts Film from the Tuple
                 toList() // Use a List collector for downstream aggregation.
            )
        )
    );

Entities are Linked

No need for joins when there is a foreign key!

// Find any film where english is spoken
Optional<Film> anyFilmInEnglish = languages.stream()
    .filter(Language.NAME.equal("English"))
    .flatMap(films.finderBackwardsBy(Film.LANGUAGE_ID))
    .findAny();

// Find the language of the film with id 42
Optional<Language> languageOfFilmWithId42 = films.stream()
    .filter(Film.FILM_ID.equal(42))
    .map(languages.finderBy(Film.LANGUAGE_ID))
    .findAny();

Easy Initialization

The SakilaApplication, SakilaApplicationBuilder and FilmManager classes are generated automatically from the database.

final SakilaApplication app = new SakilaApplicationBuilder()
    .withPassword("myPwd729")
    .build();
    
final FilmManager      films      = app.getOrThrow(FilmManager.class);
final LanguageManager  languages  = app.getOrThrow(CarrotManager.class);
final ActorManager     actors     = app.getOrThrow(ActorManager.class);
final FilmActorManager filmActors = app.getOrThrow(FilmActorManager.class);

Easy Persistence

Entities can easily be persisted in a database.

Film newFilm = new FilmImpl();  // Creates a new empty Film
newFilm.setTitle("Police Academy 13");
newFilm.setRating("G");
newFilm.setLength(123);
...

// Auto-Increment-fields have been set by the database
Film persistedFilm = films.persist(newFilm);

Update

films.stream()
    .filter(Film.ID.equal(42))   // Filters out all Films with ID = 42 (just one)
    .map(Film.LENGTH.setTo(143)) // Applies a setter that sets the length to 143
    .forEach(films.updater());   // Applies the updater function

or another example

films.stream()
    .filter(Film.ID.between(48, 102))   // Filters out all Films with ID between 48 and 102
    .map(f -> f.setRentalDuration(f.getRentalDuration() + 1)) // Applies a lambda that increases their rental duration by one
    .forEach(films.updater());          // Applies the updater function to the selected films

Remove

films.stream()
    .filter(Film.ID.equal(71))  // Filters out all Films with ID = 71 (just one)
    .forEach(films.remover());  // Applies the remover function

Transactions

txHandler().createAndAccept(tx -> {
    final List<Film> filmsToUpdate = films.stream()
        .filter(Film.LENGTH.greaterThan(75))
        .collect(toList()); // Collect all Films with length > 75
    filmsToUpdate.stream()
        .map(f -> f.setRentalDuration(f.getRentalDuration() + 1)) // Applies a lambda that increases their rental duration by one
        .forEach(films.updater());   // Applies the updater function to the selected films
    tx.commit(); // Atomically commits all updates 
})

Values can also be returned form a transaction as shown hereunder:

long rowCount = txHandler().createAndApply(tx -> 
    films.stream().count() + actors.stream().count()
    // Computes and returns the sum of rows in the two tables atomically   
)

Full Transparency

By appending a logger to the builder, you can follow exactly what happens behind the scenes.

SakilaApplication app = new SakilaApplicationBuilder()
    .withPassword("myPwd729")
    .withLogging(ApplicationBuilder.LogType.STREAM)
    .withLogging(ApplicationBuilder.LogType.PERSIST)
    .withLogging(ApplicationBuilder.LogType.UPDATE)
    .withLogging(ApplicationBuilder.LogType.REMOVE)
    .build();

Integration with Spring Boot

It is easy to integrate Speedment with Spring Boot. Here is an example of a Configuration file for Spring:

@Configuration
public class AppConfig {
    private @Value("${dbms.username}") String username;
    private @Value("${dbms.password}") String password;
    private @Value("${dbms.schema}") String schema;

    @Bean
    public SakilaApplication getSakilaApplication() {
        return new SakilaApplicationBuilder()
            .withUsername(username)
            .withPassword(password)
            .withSchema(schema)
            .build();
    }

    // Individual managers
    @Bean
    public FilmManager getFilmManager(SakilaApplication app) {
        return app.getOrThrow(FilmManager.class);
    }
}

So when we need to use a manager in a SpringMVC Controller, we can now simply autowire it:

    private @Autowired FilmManager films;

Copyright

Copyright (c) 2014-2017, Speedment, Inc. All Rights Reserved. Visit www.speedment.com for more info.