java - How to return URLs based on HATEOAS without modifying the whole response? -

i have developed service using spring boot. code (simplified):

@restcontroller @requestmapping("/cars") public class carcontroller {     @autowired     private carservice carservice;      @autowired     private carmapper carmapper;      @getmapping("/{id}")     public cardto findbyid(@pathvariable long id) {         car car = carservice.findbyid(id);         return carmapper.maptocardto(car);     } } 

carmapper defined using mapstruct. here's code (simplified well):

@mapper(componentmodel="spring",         uses={ makemodelmapper.class }) public interface carmapper {     @mappings({         //fields omitted         @mapping(source="listaimagencarro", target="rutasimagenes")     })     cardto maptocardto(car car);      string car_image_url_format = "/cars/%d/images/%d"     /*         mapstruct invoke method map car image domain object string. here's issue.     */     default string maptourl(carimage carimage) {         if (carimage == null) return null;         return string.format(                    car_image_url_format,                    carimage.getcar().getid(),                    carimage.getid()                );     } } 

the json response when invoking service:

{     "id": 9,     "make": { ... },     "model": { ... },     //more fields...     //the urls car images     "images": [         "/cars/9/images/1"     ] } 

i need images field returns valid urls regarding server , path app deployed. example, if deploy app using localhost through port 8080, this:

{     "id": 9,     "make": { ... },     "model": { ... },     //more fields...     "imagenes": [         "http://localhost:8080/cars/9/images/1"     ] } 

i've reviewed building hypermedia-driven restful web service, seems want. except need these urls, don't want change whole response object.

is there way achieve it?

spring hateoas provides linkbuilder service purpose.

try following:

import static org.springframework.hateoas.mvc.controllerlinkbuilder.linkto; import static org.springframework.hateoas.mvc.controllerlinkbuilder.methodon; //...//  linkto(methodon(carcontroller.class).findbyid(9)).withrel("addyourrelhere"); 

this should output absolute url points resource. not following hal convention, should change or remove part "withrel("")"

you can add specific dtos want change:

cardto dto = carmapper.maptocardto(car); if(dto.matches(criteria)){     dto.seturl(linkto...); } return dto; 

by way, of shown in section "create restcontroller" of tutorial mention.