Step 01 — REST skeleton¶

Obiettivo: scheletro Spring Boot avviabile con un endpoint REST minimale.

Cosa costruiamo¶

• L'entry-point SpringBootFromScratchApplication.
• Un controller ProjectController con GET e POST.
• DTO ProjectRequest e ProjectResponse come records immutabili.

Concetti chiave¶

• @SpringBootApplication — meta-stereotype che combina @Configuration, @EnableAutoConfiguration, @ComponentScan.
• @RestController — @Controller + @ResponseBody.
• ResponseEntity<T> — controllo esplicito su status code e header (Location su 201 Created).
• Records — DTO immutabili senza boilerplate (Java 21 stable).

Snippet di riferimento¶

@RestController
@RequestMapping("/api/v1/projects")
public class ProjectController {

    private final ProjectService service;

    public ProjectController(ProjectService service) {
        this.service = service;          // (1)
    }

    @PostMapping
    public ResponseEntity<ProjectResponse> create(
            @Valid @RequestBody ProjectRequest request,
            UriComponentsBuilder uriBuilder
    ) {
        ProjectResponse created = service.create(request);
        URI location = uriBuilder.path("/api/v1/projects/{id}")
                                 .buildAndExpand(created.id())
                                 .toUri();
        return ResponseEntity.created(location).body(created);  // (2)
    }
}

1. Constructor injection — Spring inietta automaticamente, niente @Autowired su field.
2. 201 Created + Location — standard REST, non 200 OK.

Esercizi¶

1. Aggiungi GET /api/v1/projects/{id} con risposta 404 se non trovato.
2. Aggiungi un endpoint HEAD per verificare l'esistenza senza body.
3. Esponi un endpoint OPTIONS con CORS configurato.

Pitfall¶

Riferimenti nel codice¶

• SpringBootFromScratchApplication
• ProjectController