Spring Hateos 2 does not make injection when creating lintTo

Question

I try to create a simple controller with spring hateoas.

The controller is the following :

@RestController
public class SearchController {

    private final List<Plugin> plugins;

    @Autowired
    public SearchController(List<Plugin> plugins) {
        this.plugins = plugins;
    }

    @GetMapping("/search")
    public CollectionModel<PluginDTO> search(
            @RequestParam(value = "name", defaultValue = "") String name) {
            List<PluginDTO> pluginsDTO = this.plugins.stream()
                .filter(plugin -> {
                    if(name.isBlank()) { // No filter case.
                        return true;
                    }
                    return plugin.getName().toLowerCase(Locale.ROOT).contains(name.toLowerCase(Locale.ROOT));
                })
                .map(plugin -> new PluginDTO(plugin.getName(), plugin.getDescription(),
                                plugin.getCapacities().stream().map(c -> new CapacityDTO(c.getName(), c.getDescription())).toList())
                                .add(
                    linkTo(methodOn(SearchController.class).one(plugin.getName())).withSelfRel(),
                    linkTo(methodOn(SearchController.class).search(name)).withRel("search"))
                )
                .toList();

            Link link = linkTo(methodOn(SearchController.class).search(name)).withSelfRel();
            return CollectionModel.of(pluginsDTO, link);
    }

    @GetMapping("/plugin")
    private PluginDTO one(@RequestParam(value = "name") String name) {

        return this.plugins.stream().filter(plugin -> plugin.getName().equals(name)).findFirst()
                .map(plugin -> new PluginDTO(plugin.getName(), plugin.getDescription(),
                        plugin.getCapacities().stream().map(c -> new CapacityDTO(c.getName(), c.getDescription())).toList())
                                .add(
                    linkTo(methodOn(SearchController.class).one("")).withSelfRel(),
                    linkTo(methodOn(SearchController.class).search("")).withRel("search"))
                )
                .orElseThrow(() -> new PluginNotFoundException(name));
    }
}

With this code linkTo(methodOn(SearchController.class).get(plugin.getName())).withSelfRel() Spring call the method on() and throw a NPE on this.plugin. It seems that @Autowire is not resolve in this case.

In the official doc : https://spring.io/guides/tutorials/rest/ Injection seems to work

Any idea why this happen ?

Answer 1

Ok, i missed the private qualifier use for the method one. Making the method public solved the problem.