How to use with Dto and without entities in presentation layer (Controller)?

[freerider7777]

Can we use some Dto in Controller like "Specification spec"
instead of "Specification spec in Controller?
To separate layers

[vanjad-sixt]

Can you elaborate more on this?
Based on this excerpt from the readme:

Alternatively you can annotate an interface:

@Spec(path="firstName", params="name", spec=Like.class)
 public interface NameSpec extends Specification<Customer> {
 }

and then use it as a controller parameter without any further annotations.

You can separate your specification object into its own interface.

Here's an example that we use in our project (modified for demonstration purposes):

@And({
    // for URL query ?id=12&id=99
    @Spec(path = "id", params = "id", spec = In.class),
    // for POST json: { filter: { id: [12, 99] } }
    @Spec(path = "id", jsonPaths = "filter.id", spec = In.class),
    // for URL query ?isbn=93-86954-21-4&isbn=93-86837-21-10
    @Spec(path = "isbn", params = "isbn", spec = In.class),
    // for POST json: { filter: { isbn: ['93-86954-21-4', '93-86837-21-10'] } }
    @Spec(path = "isbn", jsonPaths = "filter.isbn", spec = In.class),
    @Spec(path = "author", jsonPaths = "filter.author", spec = In.class),
    @Spec(path = "title", params = "title", spec = In.class),
    @Spec(path = "publishedDate", params = "publishedDateFrom", spec = GreaterThanOrEqual.class),
    @Spec(path = "publishedDate", params = "publishedDateTo", spec = LessThanOrEqual.class)
})
public interface BookSpecification extends Specification<BookEntity> { }

And the controller method is defined like:

    public Page<BookDto> listVehiclesBySpec(
            // no further annotations required, just use the interface from above:
            BookSpecification specification,
            @PageableDefault(sort = "publishedDate") Pageable pageable
    ) {
            Page<BookEntity> books = bookRepository.findAll(bookSpecification, pageable);

            return new PageImpl<>(
                    // because we have a dedicated DTO for the response (because serializing entities is bad practice),
                    // we map the entities to the DTO class here
                    // alternatively, projections can be used for that
                    books.stream().map(BookResponseDto::new).toList(),
                    pageable,
                    books.getTotalElements()
            );
    }

Is this what you are aiming for?

[freerider7777]

Hi, thanks for reply!
I mean that if we place "public interface BookSpecification extends Specification { }" it in presentation layer (the module with controller), we have to reference a domain layer module (with entities) which is not very good.