javax.persistence.NoResultException: No entity found for query JPQL Query

Question

@Entity
@Table(name = "ways", schema = "public", uniqueConstraints = @UniqueConstraint(columnNames = "gid"))
public class Ways implements java.io.Serializable {
private WaysId id;

public Ways() {
}

public Ways(WaysId id) {
    this.id = id;
}

@EmbeddedId
@AttributeOverrides({
        @AttributeOverride(name = "gid", column = @Column(name = "gid", unique = true)),
        @AttributeOverride(name = "classId", column = @Column(name = "class_id", nullable = false)),
        @AttributeOverride(name = "length", column = @Column(name = "length", precision = 17, scale = 17)),
        @AttributeOverride(name = "name", column = @Column(name = "name")),
        @AttributeOverride(name = "x1", column = @Column(name = "x1", precision = 17, scale = 17)),
        @AttributeOverride(name = "y1", column = @Column(name = "y1", precision = 17, scale = 17)),
        @AttributeOverride(name = "x2", column = @Column(name = "x2", precision = 17, scale = 17)),
        @AttributeOverride(name = "y2", column = @Column(name = "y2", precision = 17, scale = 17)),
        @AttributeOverride(name = "reverseCost", column = @Column(name = "reverse_cost", precision = 17, scale = 17)),
        @AttributeOverride(name = "rule", column = @Column(name = "rule")),
        @AttributeOverride(name = "toCost", column = @Column(name = "to_cost", precision = 17, scale = 17)),
        @AttributeOverride(name = "maxspeedForward", column = @Column(name = "maxspeed_forward")),
        @AttributeOverride(name = "maxspeedBackward", column = @Column(name = "maxspeed_backward")),
        @AttributeOverride(name = "osmId", column = @Column(name = "osm_id")),
        @AttributeOverride(name = "priority", column = @Column(name = "priority", precision = 17, scale = 17)),
        @AttributeOverride(name = "theGeom", column = @Column(name = "the_geom")),
        @AttributeOverride(name = "source", column = @Column(name = "source")),
        @AttributeOverride(name = "target", column = @Column(name = "target"))})
        //@AttributeOverride(name = "vitesse", column = @Column(name = "vitesse", precision = 17, scale = 17))})
public WaysId getId() {
    return this.id;
}

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

}
@Embeddable
public class WaysId implements java.io.Serializable {

private Integer gid;
private int classId;
private Double length;
private String name;
private Double x1;
private Double y1;
private Double x2;
private Double y2;
private Double reverseCost;
private String rule;
private Double toCost;
private Integer maxspeedForward;
private Integer maxspeedBackward;
private Long osmId;
private Double priority;
private Serializable theGeom;
private Integer source;
private Integer target;
}



public double convertidTolat1(Integer id) {
    Double lat = null;
    Query query = entityManager
            .createQuery("select n.id.x1 from Ways n where n.id.gid=:id");
    query.setParameter("id", id);
    lat = (Double) query.getSingleResult();
    return lat;
}


@GET
@Path("lat/{id}")
@Produces(MediaType.APPLICATION_JSON)
public BigDecimal getlat(@PathParam(value = "id") long id) {
    BigDecimal d = iservices.getLat(id);
    return d;
}

Hi every body, here is my code, i want to know what's wrong with my query?

Answer 1

There is nothing wrong with your query. Path expressions for Embeddables are perfectly valid in JPA. You just don't get no result for it. Javadoc for NoResultException is pretty descriptive.

Thrown by the persistence provider when Query.getSingleResult() or TypedQuery.getSingleResult() is executed on a query and there is no result to return. This exception will not cause the current transaction, if one is active, to be marked for rollback.

I would suggest wrapping getSingleResult() in a try-catch block to handle no-result case

Object result = null;
try {
    result = query.getSingleResult();
} catch (NoResultException e) {
    log.debug("No result forund for... ");
}

or to always use getResultList(), i.e.

List results = query.getResultList();
if (results.isEmpty()) {
    return null; // handle no-results case
} else {
    return results.get(0);
}

You can even sometimes go further and check DB integrity if you are expecting only one result.

if (results.size() > 1) {
    log.warn("Found duplicated result for...");
}