Question

I’m facing a strange issue using the Criteria API. I want to dynamically add a Predicate to a query.

I’m using eclipselink-2.4.0.v20120411-r11144 as JPA 2.0 implementation.

As you can see i’ve tried various methods and none worked.

How do I do that? Thanks for your replies !

@Repository("mockRepository")
public class MockRepository implements Serializable {

    private static final long serialVersionUID = 1L;

    @PersistenceContext
    private EntityManager em;

    @PostConstruct
    public void myRequest() {
        CriteriaBuilder builder = em.getCriteriaBuilder();
        CriteriaQuery<MyEntity> query = builder.createQuery(MyEntity.class);        
        Root<MyEntity> root = query.from(MyEntity.class);

        query.where(builder.like(root.get("myAttr").as(String.class), "%foo%")); // SELECT ID, MYATTR, MYSECONDATTR FROM MYENTITY WHERE MYATTR LIKE ? -> Orignal query


        //query = addRestriction_1(builder, query, root); // SELECT ID, MYATTR, MYSECONDATTR FROM MYENTITY WHERE ((MYATTR LIKE ? = ?) AND (MYSECONDATTR = ?)) -> query fails



        //query = addRestriction_2(builder, query, root); // SELECT ID, MYATTR, MYSECONDATTR FROM MYENTITY WHERE ((MYATTR LIKE ? = ?) AND (MYSECONDATTR = ?)) -> query fails



        //query = addRestriction_3(builder, query, root); // SELECT ID, MYATTR, MYSECONDATTR FROM MYENTITY WHERE MYATTR LIKE ? -> where is my second predicate ??


        em.createQuery(query).getResultList(); 
    }


    private CriteriaQuery<MyEntity> addRestriction_1(CriteriaBuilder builder, CriteriaQuery<MyEntity> query, Root<MyEntity> root) {
        query.where(
                query.getRestriction(),
                builder.equal(root.get("mySecondAttr").as(String.class), "bar")
        );
        return query;
    }

    private CriteriaQuery<MyEntity> addRestriction_2(CriteriaBuilder builder, CriteriaQuery<MyEntity> query, Root<MyEntity> root) {     
        Predicate p = query.getRestriction();
        Predicate p1 = builder.equal(root.get("mySecondAttr").as(String.class), "bar");
        Predicate p2 = builder.and(p, p1);
        query.where(p2);
        return query;
    }

    private CriteriaQuery<MyEntity> addRestriction_3(CriteriaBuilder builder, CriteriaQuery<MyEntity> query, Root<MyEntity> root) {
        query.getRestriction().getExpressions().add(
                 builder.equal(root.get("mySecondAttr").as(String.class), "bar")
        );
        return query;
    }
}




@Entity
public class MyEntity implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    private Long id;

    private String myAttr;
    private String mySecondAttr;

    public String getMyAttr() {
        return myAttr;
    }

    public void setMyAttr(String myAttr) {
        this.myAttr = myAttr;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getMySecondAttr() {
        return mySecondAttr;
    }

    public void setMySecondAttr(String mySecondAttr) {
        this.mySecondAttr = mySecondAttr;
    }
}

Answer 1

This seems to be a bug in getRestriction(), if it is an Expression it is returning an invalid Predicate. If it is a Predicate it works though, so my guess is if you change your first query to,

query.where(builder.and(builder.like(root.get("myAttr").as(String.class), "%foo%"), builder.like(root.get("myAttr").as(String.class), "%foo%"));

then it will work.

Please log the bug and vote for it.