feat: @RestResource annotation and source generation

[sdelamo]

This PR adds the @RestResource annotation and a visitor. The idea is to generate to controller given Micronaut Data CrudRepository.

For example, for a Book entity:

import io.micronaut.core.annotation.Nullable;
import io.micronaut.data.annotation.GeneratedValue;
import io.micronaut.data.annotation.Id;
import io.micronaut.data.annotation.MappedEntity;
import io.micronaut.serde.annotation.Serdeable;

@Serdeable
@MappedEntity
public record Book(@GeneratedValue @Id @Nullable Long id, String title) {
}

and a JDBC repository:

import io.micronaut.data.jdbc.annotation.JdbcRepository;
import io.micronaut.data.model.query.builder.sql.Dialect;
import io.micronaut.data.repository.CrudRepository;

@JdbcRepository(dialect = Dialect.H2)
public interface BookRepository extends CrudRepository<Book, Long> {
}

And a class annotated with @RestResource:

import io.micronaut.sourcegen.annotations.RestResource;

@RestResource(repository = BookRepository.class, rolesAllowed = { "isAnonymous()" })
class BookRestResource {
}

Generates the following controller:

@Controller("/books")
@RolesAllowed("isAnonymous()")
class BookController {
  @Inject
  BookRepository repository;

  @Get
  Iterable<Book> findAll() {
    return this.repository.findAll();
  }

  @Get("/{id}")
  Optional<Book> findById(Long id) {
    return this.repository.findById(id);
  }

  @Delete("/{id}")
  @Status(HttpStatus.NO_CONTENT)
  void deleteById(Long id) {
    this.repository.deleteById(id);
  }

  @Status(HttpStatus.CREATED)
  @Post
  void save(@Body Book entity) {
    this.repository.save(entity);
  }

  @Put
  @Status(HttpStatus.NO_CONTENT)
  void update(@Body Book entity) {
    this.repository.update(entity);
  }
}

I would prefer to generate

repository.deleteById(id);

instead of

this.repository.deleteById(id)

but not sure how to do this with the api.

Also, the save method should probably be: but that was challenging with the current API as well.

Book savedBook = bookRepository.save(book);
return HttpResponse.created(UriBuilder.of("/books").path(savedBook.id().toString()).build());

thoughts ?

[sdelamo]

I used field injection because I did not see in the api how to generate a constructor and use constructor injection.

[graemerocher]

looks useful but would be good to have meta annotations for create/read/update/delete and have @RestResource be a meta annotation

That said this could also be achieved with an interface with default methods which may be more natural/easier to extend.

[sonarcloud]

Quality Gate failed

Failed conditions
0.0% Coverage on New Code (required ≥ 70%)

See analysis details on SonarCloud

[dstepanov]

It might be good to generate some DTOs and allow to make some fields hidden, readonly etc

[graemerocher]

interface CrudResource<E, I> {
    CrudRepository<E, I> repository();

    @Get
    default Iterable<Book> findAll() {
        return repository().findAll();
    }

    @Get("/{id}")
    default Optional<Book> findById(Long id) {
        return repository().findById(id);
    }

    @Delete("/{id}")
    @Status(HttpStatus.NO_CONTENT)
    default void deleteById(Long id) {
        repository().deleteById(id);
    }

    @Status(HttpStatus.CREATED)
    @Post
    default void save(@Body Book entity) {
        repository().save(entity);
    }

    @Put
    @Status(HttpStatus.NO_CONTENT)
    default void update(@Body Book entity) {
        repository().update(entity);
    }
}

@Controller("/books")
@RolesAllowed("isAnonymous()")
record BookResource(BookRepository repository) implements CrudResource<Book, Long> {
}

CrudResource could be composed of different interfaces for CRUD operations that can be selectively overridden to customise behaviour.

The code generation approach has limitations in terms of how you can customise the output.

[sdelamo]

interface CrudResource<E, I> {
    CrudRepository<E, I> repository();

    @Get
    default Iterable<Book> findAll() {
        return repository().findAll();
    }

    @Get("/{id}")
    default Optional<Book> findById(Long id) {
        return repository().findById(id);
    }

    @Delete("/{id}")
    @Status(HttpStatus.NO_CONTENT)
    default void deleteById(Long id) {
        repository().deleteById(id);
    }

    @Status(HttpStatus.CREATED)
    @Post
    default void save(@Body Book entity) {
        repository().save(entity);
    }

    @Put
    @Status(HttpStatus.NO_CONTENT)
    default void update(@Body Book entity) {
        repository().update(entity);
    }
}

@Controller("/books")
@RolesAllowed("isAnonymous()")
record BookResource(BookRepository repository) implements CrudResource<Book, Long> {
}

CrudResource could be composed of different interfaces for CRUD operations that can be selectively overridden to customise behaviour.

The code generation approach has limitations in terms of how you can customise the output.

but such an api will be in Micronaut Data not here right?

[graemerocher]

probably