GraphQL APIs
Para integrar GraphQL en Spring Boot estas librerías son necesarias (deben añadirse manualmente):
- graphql-spring-boot-starter - Este starter es muy útil porque configura automáticamente un Servlet GraphQL al que puedes acceder a través de /graphql.
- graphql-java-tools - Una librería de ayuda para parsear el esquema de GraphQL.
GraphQL schema (.graphqls)
Define los data points que ofrece la API. Incluye los tipos de datos, las relaciones entre ellos y las operaciones que podemos realizar sobre ellos.type Location {
id: ID!
name: String!
address: String!
}
type Query {
findAllLocations: [Location]!
}
type Mutation {
newLocation(name: String!, address: String) : Location!
deleteLocation(id:ID!) : Boolean
updateLocationName(newName: String!, id:ID!) : Location!
}
Operations
Las operaciones que GraphQL ofrece sobre los datos son:- Queries: nos permiten obtener datos. Cada query tendra su propio objeto.
- Mutations: podemos actualizar la información almacenada en el servidor (Create, Update y Delete).
{
"query": {findAllLocations {name id address} }"
}
Además de Postman y otras herramientas del estilo, disponemos de GraphiQL para testear nuestra GraphQL API.
Ejemplo:
Location.java
@Entity
public class Location {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String name;
private String address;
public Location(Long id, String name, String address) {
this.id = id;
this.name = name;
this.address = address;
}
public Location(String name, String address) {
this.name = name;
this.address = address;
}
public Location() {}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
LocationNotFoundException
public class LocationNotFoundException extends RuntimeException implements GraphQLError {
private Map<String, Object> extensions = new HashMap<>();
public LocationNotFoundException(String message, Long invalidLocationId) {
super(message);
extensions.put("invalidLocationId", invalidLocationId);
}
@Override
public List<SourceLocation> getLocations() {
return null;
}
@Override
public Map<String, Object> getExtensions() {
return extensions;
}
@Override
public ErrorType getErrorType() {
return ErrorType.DataFetchingException;
}
}
Mutation.java
@Component
public class Mutation implements GraphQLMutationResolver {
private LocationRepository locationRepository;
public Mutation(LocationRepository locationRepository) {
this.locationRepository = locationRepository;
}
public Location newLocation(String name, String address) {
Location location = new Location(name, address);
locationRepository.save(location);
return location;
}
public boolean deleteLocation(Long id) {
locationRepository.deleteById(id);
return true;
}
public Location updateLocationName(String newName, Long id) {
Optional<Location> optionalLocation =
locationRepository.findById(id);
if(optionalLocation.isPresent()) {
Location location = optionalLocation.get();
location.setName(newName);
locationRepository.save(location);
return location;
} else {
throw new LocationNotFoundException("Location Not Found", id);
}
}
}
LocationRepository.java
public interface LocationRepository extends CrudRepository {
}
Query.java
@Component
public class Query implements GraphQLQueryResolver {
private LocationRepository locationRepository;
public Query(LocationRepository locationRepository) {
this.locationRepository = locationRepository;
}
public Iterable<Location> findAllLocations() {
return locationRepository.findAll();
}
}
LocationService.java
public interface LocationService {
List retrieveLocations();
}
LocationServiceImpl.java
@Service
public class LocationServiceImpl implements LocationService {
@Autowired
LocationRepository locationRepository;
public List<Location> retrieveLocations() {
return (List<Location>) locationRepository.findAll();
}
}
LocationController.java
@RestController
public class LocationController {
private LocationService locationService;
@Autowired
public void setLocationService(LocationService locationService) {
this.locationService = locationService;
}
@GetMapping("/location")
public ResponseEntity<List<Location>> getAllLocations() {
List<Location> list = locationService.retrieveLocations();
return new ResponseEntity<List<LocationGlt;>(list, HttpStatus.OK);
}
}
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