Spring Boot Jpa specification Set Enums IN Set Enums

Hi I want filter restaurant by type using Specification, but I get error:

Parameter value [SUSHI] did not match expected type [java.util.Set (n/a)]

How Can I comare List enums to list enums ? :/

My specification file:

if(Objects.nonNull(category)){
    predicates.add(root.get(Restaurant_.category).in(category));
}

Restaurant model:

@ElementCollection(targetClass = RestaurantCategory.class)
@Enumerated(EnumType.STRING)
@CollectionTable(name = "restaurant_category")
private Set<RestaurantCategory> category;

Restaurant category:

public enum RestaurantCategory {
    STREET_FOOD, SUSHI, PIZZA, BURGER
}

Answer

Had the same problem and this question helped me.

In my case, I wanted to search my commissions by country. Here how I solved my issue.

Domain:

@Entity
@Table(name = "commission")
data class Commission(
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    var id: Long? = 0,

    @ElementCollection(fetch = FetchType.EAGER)
    @Enumerated(EnumType.STRING)
    var countries: MutableSet<CountryCode>? = null,

    @get: NotNull
    @Enumerated(EnumType.STRING)
    @Column(name = "type", nullable = false)
    var type: CommissionType? = null
) 

Specification code (@see findByCountries part):

object CommissionSpecifications {
fun buildQuery(request: SearchCommissionRequest): Specification<Commission> {

    var query = Specification.where<Commission>(distinct())

    request.type?.also { query = query?.and(findByType(it)) }
    request.countries?.also { if (it.isNotEmpty()) query = query?.and(findByCountries(it)) }

    return query!!
}

private fun findByType(type: CommissionType): Specification<Commission> =
    Specification { root, _, cb -> cb.equal(root.get<Commission>(Commission::type.name), type) }

private fun findByCountries(countries: Set<CountryCode>): Specification<Commission> =
    Specification { root, _, _ ->
        root.join<Commission, Set<CountryCode>>(Commission::countries.name).`in`(countries)
    }

private fun distinct(): Specification<Commission?> {
    return Specification { root: Root<Commission?>?, query: CriteriaQuery<*>, cb: CriteriaBuilder? ->
        query.distinct(true)
        null
    }
}

}