How to ignore LAZY types dynamically on SpringBoot app?

Question

I have a class:

@Entity
@Table(name = "restaurants")
public class Restaurant extends AbstractNamedEntity implements Serializable {

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "restaurant")
    private Set<Meal> meals = Collections.emptySet();

    //other fields, getters, setters, constructors
}

I'm getting my data with Spring Data:

@Repository
public interface RestaurantRepository extends CrudRepository<Restaurant, Integer> {

}

I have REST-controller, which produces JSON data:

@RestController
@RequestMapping(value = RestaurantController.REST_URL, produces = MediaType.APPLICATION_JSON_VALUE + ";charset=UTF-8")
public class RestaurantController {
    static final String REST_URL = "/restaurants";

    @Autowired
    private RestaurantRepository repository;

    @GetMapping("{id}")
    public List<Restaurant> getOne(@PathVariable Integer id) {
        return repository.findById(id);
    }
}

How to avoid including that LAZY data (set of Meals) to get them to a SQL request? As I know I need to write a custom JacksonObjectMapper, but I don't know how to do it

Answer 1

You can use @JsonIgnore annotation in order to ignore the mapping of a field. Then you should do this:

@JsonIgnore
@OneToMany(fetch = FetchType.LAZY, mappedBy = "restaurant")
private Set<Meal> meals = Collections.emptySet();

UPDATED

Based what you want to do " Ignore field dynamically when getting one or not getting alls " you can use @NamedEntityGraphs annotation to specific what fields you want to join, then by using @NamedEntityGraph you specify the path and boundaries for a find operation or query and you should use in your custom Repository the @EntityGraph annotation who allows to customize the fetch-graph based what you want to do.

So you should add the following code:

@Entity
@Table(name = "restaurants")
@NamedEntityGraphs({
    @NamedEntityGraph(name="Restaurant.allJoins", includeAllAttributes = true),
    @NamedEntityGraph(name="Restaurant.noJoins")
})
public class Restaurant extends AbstractNamedEntity implements Serializable {

}

@Repository
public interface RestaurantRepository extends CrudRepository<Restaurant, Integer> {

    @EntityGraph(value = "Restaurant.allJoins", type = EntityGraphType.FETCH)
    @Override
    List<Restaurant> findAll();

    @EntityGraph(value = "Restaurant.noJoins", type = EntityGraphType.FETCH)
    @Override
    Optional<Restaurant> findById(Integer id);

}