Spring Data Specification orderBy subquery - spring-data-jpa

Question

On my MySql project I got this particular model with 3 entities: Prodotto with many childs QuotaIngrediente, that in turn is Many-to-One child of Ingrediente too. All my relationships are bi-directional.
All of them got an autogenerated integer Id and other fields removed to focus on the interesting ones.
#Entity
public class Prodotto {
private List<QuotaIngrediente> listaQuoteIng = new ArrayList<QuotaIngrediente>();
#OneToMany(mappedBy = "prodotto", cascade = CascadeType.ALL, orphanRemoval = true)
public List<QuotaIngrediente> getListaQuoteIng() {
return listaQuoteIng;
}
#Entity
public class QuotaIngrediente{
private Prodotto prodotto;
private Ingrediente ing;
private Double perc_ing;
#ManyToOne
#JoinColumn(name = "prodotto")
public Prodotto getProdotto() {
return prodotto;
}
#ManyToOne
#JoinColumn(name = "ing")
public Ingrediente getIng() {
return ing;
}
#Entity
public class Ingrediente {
private Set<QuotaIngrediente> quoteIng = new HashSet<QuotaIngrediente>();
#OneToMany(mappedBy = "ing", cascade = CascadeType.ALL, orphanRemoval = true)
public Set<QuotaIngrediente> getQuoteIng() {
return quoteIng;
}
I'm using SpringData Specification and I can build a query to get Prodotto based on Ingrediente criteria, this way:
public static Specification<Prodotto> getProdottoByIngSpec (String ing) {
if (ing != null) {
return (root, query, criteriaBuilder) -> {
query.groupBy(root.get(Prodotto_.id));
return criteriaBuilder.like(((root.join(Prodotto_.listaQuoteIng))
.join(QuotaIngrediente_.ing))
.get(Ingrediente_.nome), "%"+ing+"%");
};
It works as expected, but now I want to sort it by the QuotaIngrediente perc_ing field OF THAT SPECIFIC INGREDIENTE.
Obviously I'm asking how to do it on DB, not in business logic.

Answer 1

I was struggling with a false problem due to a wrong assumption of mine. Solution was the simplest. Just sort by orderBy CriteriaQuery method. The query I used to search already filtered the QuotaIngrediente returning just the lines that match my search criteria. Then this is the only line I had to add to my Specification:
query.orderBy(builder.desc((root.join(Prodotto_.listaQuoteIng))
.get(QuotaIngrediente_.perc_ing)));