Hi folks,
I am using the Criteria-API to find Entities matching some more complicated
conditions. My (simplified) Entities look like the following code:
@Entity
public class User implements Serializable {
@Id
private Long id;
@Basic
private String name;
@Basic
private String avatar;
@Basic
private String profile;
@OneToOne(mappedBy = "owner")
private Inventory inventory;
...
}
@Entity
public class Inventory implements Serializable {
@Id
@OneToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "Owner", referencedColumnName = "Id")
private User owner;
@Basic
private int slots;
@Basic
@Enumerated(EnumType.STRING)
private Visibility visibility;
@OneToMany(cascade = {CascadeType.ALL}, orphanRemoval = false)
@JoinTable(
name = "Ownership",
joinColumns = {
@JoinColumn(name = "Inventory", referencedColumnName = "Owner",
unique = false)
},
inverseJoinColumns = {
@JoinColumn(name = "Item", referencedColumnName = "Id", unique
= true)
}
)
private Set<Item> content;
...
}
@Entity
public class Item implements Serializable {
@Id
private Integer id;
@Basic
private String name;
@Basic
private String description;
...
}
Note that I use use a mapping of derived identities for the relation
Inventory <-> User. Based on this, I try to execute a query with a fetch
using the Criteria-API to retrieve inventories, to have the associated user
available.
private List<Inventory> findInventories(...) {
CriteriaBuilder builder = this.manager.getCriteriaBuilder();
CriteriaQuery<Inventory> query = builder.createQuery(Inventory.class);
Root<Inventory> inventory = query.from(Inventory.class);
// This should also load the user data to avoid an additional SELECT
satement
Fetch<Inventory, User> owner = inventory.fetch("owner", JoinType.INNER);
...
TypedQuery<Inventory> typedQuery = this.manager.createQuery(query);
return typedQuery.getResultList();
}
I omited the WHERE-clause, to keep things simple.
The trace shows me, that the resulting SQL query (especially the
SELECT-claue) looks like expected.
SELECT t0.Owner, t3.Id, t3.Avatar, t3.Name, t3.Profile, t0.Slots,
t0.Visibility
FROM Inventories t0 INNER JOIN Ownership t1 ON t0.Owner = t1.Inventory
INNER JOIN Users t3 ON t0.Owner = t3.Id INNER JOIN Items t2
ON t1.Item = t2.Id
WHERE ...
However, if I debug the code, I can see, that the properties of the
User-objects are all NULL except the id. This results in an additional
SELECT if I try to access these properties. On the other hand I added an
additional fetch (Join<Inventory, Item> content = inventory.fetch("content",
JoinType.INNER)) to also load the content of the inventories which works as
expected. Here all the properties of the items are initialized with the
actual values.
Since the second part works as expected, I assume a bug if I use a mapping
of derived identities and any feedback to my problem would be welcome.
Regards
Riccardo
--
View this message in context:
http://openjpa.208410.n2.nabble.com/Problem-with-Criteria-API-and-fetch-properties-of-related-entities-are-NULL-tp7582995.html
Sent from the OpenJPA Users mailing list archive at Nabble.com.
