A basic entity that has a OneToOne reference to another entity:
#Entity
public class Friend {
// ...
#OneToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
private Friend bestFriend;
}
I'd like to build a select query, that contains some of the fields and the best friend id.
In plain SQL it's trivial: SELECT bestfriendid FROM friend WHERE id = 123
With JPA criteria API things get very interesting:
EntityManager em = ...
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Tuple> query = cb.createQuery(Tuple.class);
Root<Friend> root = query.from(Friend.class);
query.multiselect(root.get(Friend_.bestFriend).get(Friend_.id), root.get(Friend_.name));
query.where(cb.equal(root.get(Friend_.id), id));
return em.createQuery(query).getSingleResult();
This does work for a friend with a best friend set, but the generated SQL is dumb: SELECT t0.ID, t1.NAME FROM FRIEND t0, FRIEND t1 WHERE ((t1.ID = ?) AND (t0.ID = t1.BESTFRIEND_ID))
Also it does not work on a fried who has no best friend.
I'd like to see a simple SELECT t0.NAME, t0.BESTFRIEND_ID FROM FRIEND t0 WHERE t0.ID = ?.
Can root.get(Friend_.bestFriend).get(Friend_.id) be swapped for something else to achieve this?
The solution is another field:
#JoinColumn(name = "friend_id")
#OneToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
public Friend bestFriend;
#Column(name = "friend_id", insertable = false, updatable = false)
public long friendId;
This gives me access to the friend id using root.get(Friend_.friendId).
Related
I have two entities, in one to many relationship. I am trying to join the collection of entities, but can't wrap my head around it how to use the framework. I always used hibernate's DetachedCriteria but is not an option for me anymore, any help would be great.
#Entity
#Table(name = "Project")
public class Project implements Serializable {
....
#OneToMany(cascade = CascadeType.ALL, mappedBy = "project")
private Collection<WorkReport> workReportCollection;
....
#Data
#Entity
#Table(name = "work_report")
public class WorkReport implements Serializable {
#JoinColumn(name = "id_work_report", referencedColumnName = "id_work_report", insertable = false, updatable = false)
#ManyToOne(optional = false)
private Project project;
And I am trying to join workReportCollection like this, but it always throws
LazyInit Exception
when accessing the field.
CriteriaBuilder builder = em.getCriteriaBuilder();
CriteriaQuery<Project> query = builder.createQuery(Project.class);
Root<Project> project = query.from(Project.class);
Predicate idPredicate = builder.equal(project.get("idProject"), idProject);
project.joinCollection("workReportCollection", JoinType.LEFT);
query.where(idPredicate);
TypedQuery<Project> q = em.createQuery(query);
return q.getSingleResult();
Only thing that works is using fetch instead of join but it fetches all other associations as well and that is too much data.
How to write a join correctly with JPA CriteriaBuilder? OR Should I use a fetch with some projection?
The join is correct but the collection is not initialized when you access it that's why you get the LazyInitException.
You have to add fetch:
project.fetch("workReportCollection");
to advice JPA to initialize the collection after querying.
I'm using QueryHints in Spring Data JPA to use EclipseLink Batch Fetch with a type of IN. Ultimately, I need to use this around 30 fields but it doesn't seem to work right for 2 fields. Field A has a ManyToOne relationship and Field B has a ManyToMany. Based on the results of the initial query, I would expect the batch hint to generate an IN clause with 2 ids for Field A and 12 for Field B. This works fine when the hint is turned on for one field at a time. When it is enabled for both fields, the hint only applies to whichever field is the last hint in the list of QueryHints. I've tried EAGER and LAZY fetch on the fields as a shot in the dark, but it had not impact.
Is there a limitation with mixing batch fetch hints based on the relationship type? Is there something different going on? The EclipseLink documentation isn't very detailed for this feature.
EDIT: It seems it doesn't matter what fields I enable it only, it only works for one at at time. Here is sample code for two entities. The BaseEntity defines the PK id generation.
#Entity
#Table(name = "MainEntity")
public class MainEntity extends BaseEntity implements Cloneable {
...
#ManyToMany(fetch=FetchType.LAZY, cascade=CascadeType.PERSIST)
#JoinTable(
name="EntityBMapping",
joinColumns={#JoinColumn(name="mainId", referencedColumnName="id")},
inverseJoinColumns={#JoinColumn(name="bId", referencedColumnName="id")})
#JsonIgnore
private Set<EntityB> bSet = new HashSet<>();
#ManyToMany(fetch=FetchType.LAZY, cascade=CascadeType.ALL)
#JoinTable(
name="EntityAMapping",
joinColumns={#JoinColumn(name="mainId", referencedColumnName="id")},
inverseJoinColumns={#JoinColumn(name="aId", referencedColumnName="id")})
#JsonIgnore
#OrderColumn(name="order_index", columnDefinition="SMALLINT")
private List<EntityA> aList = new ArrayList<>();
...
}
#Entity
#Cache(type=CacheType.FULL)
#Table(name = "EntityA")
public class EntityA extends BaseEntity {
#Column(name = "name", columnDefinition = "VARCHAR(100)")
private String name;
#ManyToMany(mappedBy = "entityASet", fetch=FetchType.LAZY)
#JsonIgnore
private Set<MainEntity> mainEntityList = new HashSet<>();
}
#Entity
#Cache(type=CacheType.FULL)
#Table(name = "EntityB")
public class EntityB extends BaseEntity {
#Column(name = "name", columnDefinition = "VARCHAR(100)")
private String name;
#ManyToMany(mappedBy = "entityBSet", cascade=CascadeType.ALL)
#JsonIgnore
private Set<MainEntity> mainEntityList = new HashSet<>();
}
The repository query:
#QueryHints(value = {
#QueryHint(name = org.eclipse.persistence.config.QueryHints.BATCH_TYPE, value = "IN"),
#QueryHint(name = org.eclipse.persistence.config.QueryHints.BATCH_SIZE, value = "250"),
#QueryHint(name = org.eclipse.persistence.config.QueryHints.BATCH, value = "o.aList")},
#QueryHint(name = org.eclipse.persistence.config.QueryHints.BATCH, value = "o.bSet")},
forCounting = false)
List<MainEntity> findAll(Specification spec);
Generated queries:
SELECT id, STATUS, user_id FROM MainEntity WHERE ((STATUS = ?) OR ((STATUS = ?) AND (user_id = ?)))--bind => [ONESTAT, TWOSTAT, myuser]
..
SELECT t1.id, t1.name, t0.order_index FROM EntityAMapping t0, EntityA t1 WHERE ((t0.mainId = ?) AND (t1.id = t0.aId))--bind => [125e17d2-9327-4c6b-a65d-9d0bd8c040ac]
...
SELECT t1.id, t1.name, t0.mainId FROM EntityBMapping t0, EntityB t1 WHERE ((t1.id = t0.bId) AND (t0.mainId IN (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)))--bind => [125e17d2-9327-4c6b-a65d-9d0bd8c040ac, 1c07a3a9-7028-48ba-abe8-2296d58ebd57, 235bb4f2-d724-4237-b73b-725db2b9ca9f, 264f64b3-c355-4476-8530-11d2037b1f3c, 2d9a7044-73b3-491d-b5f1-d5b95cbb1fab, 31621c93-2b0b-4162-9e42-32705b7ba712, 39b33b19-c333-4523-a5a7-4ba0108fe9de, 40ba7706-4023-4b7e-9bd5-1641c5ed6498, 52eed760-9eaf-4f6a-a36f-076b3eae9297, 71797f0c-5528-4588-a82c-5e1d4d9c2a66, 89eda2ef-80ff-4f54-9e6a-cf69211dfa61, 930ba300-52fa-481c-a0ae-bd491e7dc631, 96dfadf9-2490-4584-b0d4-26757262266d, ae079d02-b0b5-4b85-8e6f-d3ff663afd6e, b2974160-33e8-4faf-ad06-902a8a0beb04, b86742d8-0368-4dde-8d17-231368796504, caeb79ce-2819-4295-948b-210514376f60, cafe838f-0993-4441-8b99-e012bbd4c5ee, da378482-27f9-40b7-990b-89778adc4a7e, e4d7d6b9-2b8f-40ab-95c1-33c6c98ec2ee, e557acf4-df01-4e66-9d5e-84742c99870d, ef55a83c-2f4c-47b9-99bb-6fa2f5c19a76, ef55a83c-2f4c-47b9-99bb-6fa2f5c19a77]
...
SELECT t1.id, t1.name, t0.order_index FROM EntityAMapping t0, EntityA t1 WHERE ((t0.mainId = ?) AND (t1.id = t0.aId))--bind => [1c07a3a9-7028-48ba-abe8-2296d58ebd57]
As Chris mentioned, Named Queries are the best work around for this issue. The other option is to use a custom repository and call setHint on the EntityManager yourself for each hint specified (plenty of examples out there for creating custom repos in Spring Data JPA). You could attempt to override findOne(...) and protected <S extends T> TypedQuery<S> getQuery(Specification<S> spec, Class<S> domainClass, Sort sort) on SimpleJpaRepository to try and create a generic way to properly set the hints but you'll likely want to check that you don't duplicate hint setting on getQuery(...) as you'll still want to call super() for that and then apply your additional hints before returning the query. I'm not sure what the behavior would be if you applied a duplicate hint. Save yourself the trouble and use Named Queries is my advice.
How do I create an efficient JPA Criteria query to select a list of entities only if they exist in a join table? For example take the following three tables:
create table user (user_id int, lastname varchar(64));
create table workgroup (workgroup_id int, name varchar(64));
create table user_workgroup (user_id int, workgroup_id int); -- Join Table
The query in question (what I want JPA to produce) is:
select * from user where user_id in (select user_id from user_workgroup where workgroup_id = ?);
The following Criteria query will produce a similar result, but with two joins:
CriteriaBuilder cb = getEntityManager().getCriteriaBuilder();
CriteriaQuery<User> cq = cb.createQuery(User.class);
Root<User> root = cq.from(User.class);
cq.select(root);
Subquery<Long> subquery = cq.subquery(Long.class);
Root<User> subroot = subquery.from(User.class);
subquery.select(subroot.<Long>get("userId"));
Join<User, Workgroup> workgroupList = subroot.join("workgroupList");
subquery.where(cb.equal(workgroupList.get("workgroupId"), ?));
cq.where(cb.in(root.get("userId")).value(subquery));
getEntityManager().createQuery(cq).getResultList();
The fundamental problem seems to be that I'm using the #JoinTable annotation for the USER_WORKGROUP join table instead of a separate #Entity for the join table so it doesn't seem I can use USER_WORKGROUP as a Root in a criteria query.
Here are the entity classes:
#Entity
public class User {
#Id
#Column(name = "USER_ID")
private Long userId;
#Column(name = "LASTNAME")
private String lastname;
#ManyToMany(mappedBy = "userList")
private List<Workgroup> workgroupList;
}
#Entity
public class Workgroup {
#Id
#Column(name = "WORKGROUP_ID")
private Long workgroupId;
#Column(name = "NAME")
private String name;
#JoinTable(name = "USER_WORKGROUP", joinColumns = {
#JoinColumn(name = "WORKGROUP_ID", referencedColumnName = "WORKGROUP_ID", nullable = false)}, inverseJoinColumns = {
#JoinColumn(name = "USER_ID", referencedColumnName = "USER_ID", nullable = false)})
#ManyToMany
private List<User> userList;
}
As far as I know, JPA essentially ignores the join table. The JPQL that you do would be
select distinct u from user u join u.workgroupList wg where wg.name = :wgName
for the Criteria query, you should be able to do:
Criteria c = session.createCriteria(User.class, "u");
c.createAlias("u.workgroupList", "wg");
c.add(Restrictions.eq("wg.name", groupName));
c.setResultTransformer(Criteria.DISTINCT_ROOT_ENTITY);
there's no need to worry about the middle join table.
I have the following class:
#Entity
#Table(name = "entity")
public class Entity extends Model
{
#ManyToMany(fetch = FetchType.EAGER)
#JoinTable(name = "entity_owner", joinColumns = #JoinColumn(name = "entity_id"), inverseJoinColumns = #JoinColumn(name = "user_id"))
private Set<UserAccount> owners;
#ManyToMany(fetch = FetchType.EAGER)
#JoinTable(name = "entity_assignee", joinColumns = #JoinColumn(name = "entity_id"), inverseJoinColumns = #JoinColumn(name = "user_id"))
private Set<UserAccount> assignees;
}
I have a user account that I want to be able to being back all the Entity objects that have the user in either the owners or the assignees.
I tried this, which almost works, but seems to being back some sort of cartesian result:
String query = "SELECT r FROM models.Entity r LEFT JOIN r.assignees a LEFT JOIN r.owners n ";
query += "WHERE a.id = 1 OR n.id = 1";
Can anyone tell me what I am doing wrong?
If the UserAccount is in both owners and assignees, seems like the query will duplicate a result, you can use DISTINCT to filter duplicated results:
SELECT DISTINCT r FROM ...
When there is instance of UserAccount already available for filtering results,
MEMBER OF expression can be used:
SELECT DISTINCT(e)
FROM SomeEntity e
WHERE :someUser MEMBER OF e.assignees OR
:someUser MEMBER OF e.owners
UserAccount ua ...
em.createQuery(jpql).setParameter("someUser", ua)
If because of some reason query similar to original query is preferred, then adding DISTINCT is enough.
I want make a query where I join 2 tables, using the CriteriaBuilder. In MySQL the query I'm trying to make would look like this:
SELECT * FROM order
LEFT JOIN item
ON order.id = item.order_id
AND item.type_id = 1
I want to get all orders and if they have an item of type #1, I want to join with this item. However, if no item of type #1 is found, I still want to get the order. I can't figure out how to make this with the CriteriaBuilder. All I know how to make is:
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Order> cq = cb.createQuery(Order.class);
Root<Order> order = cq.from(Order.class);
Join<Order, Item> item = order.join(Order_.itemList, JoinType.LEFT);
Join<Item, Type> type = order.join(Item_.type, JoinType.LEFT);
cq.select(order);
cq.where(cb.equal(type.get(Type_.id), 1));
This query is broke, since it results in something like this in MySQL:
SELECT * FROM order
LEFT JOIN item
ON order.id = item.order_id
WHERE item.type_id = 1
The result will only contain orders with items of type #1. Orders without are excluded. How can I use the CriteriaBuilder to create a query like in the first example?
It is possible starting from the version 2.1 of JPA using the on method Join<Z, X> on(Predicate... restrictions);
Here is how:
Root<Order> order = cq.from(Order.class);
Join<Order, Item> item = order.join(Order_.itemList, JoinType.LEFT);
item.on(cb.equal(item.get(Item_.type), 1));
I think this is the same problem as posed in this question. It looks like it is not possible in CriteriaBuilder. It is possible in Hibernate Criteria API, but that probably won't help you.
JPA Criteria API: Multiple condition on LEFT JOIN
I know this question was made a long time a go, but recently a had the same problem and i found this solution from an Oracle forum, i copied and pasted just in case the link is not longer available.
MiguelChillitupaArmijos 29-abr-2011 1:41 (en respuesta a 840578) Think
you should use something like:
em.createQuery("SELECT DISTINCT e.Id" +
" from Email e " +
" left join e.idEmailIn e2 *with* e2.responseType = 'response'" +
" where e.type = 'in' and e.responseMandatory = true").getSingleResult();
An this is the link.
JPA Criteria : LEFT JOIN with an AND condition
There is a workaround if you are using Hibernate 3.6 with JPA 2.0
It is not the better solution, however it works perfect for me.
I´ve duplicate the entity with the #Where hibernate annotation.It means that everytime you use the join with this entity, hibernate will add the extra condition on the join statement at generated SQL.
For instance, initially we have the follow example:
#Entity
#Table(name = "PERSON")
public class Person {
#Id
#Column(name = "PERSON_ID")
private Long id;
#Id
#Column(name = "PERSON_NAME")
private String name;
#OneToMany(mappedBy = "person", fetch = FetchType.LAZY)
private Set<Address> addresses;
}
#Entity
#Table(name = "ADDRESS")
public class Address {
#Id
#Column(name = "ADDRESS_ID")
private Long id;
#Id
#Column(name = "ADDRESS_STREET")
private String street;
#ManyToOne
#JoinColumn(name = "PERSON_ID")
private Person person;
}
In order to add extra conditions on criteria Join, we need duplicate the Address #Entity mapping , adding the #Where annotation #Where(clause = " ADDRESS_TYPE_ID = 2").
#Entity
#Table(name = "ADDRESS")
#Where(clause = " ADDRESS_TYPE_ID = 2")
public class ShippingAddress {
#Id
#Column(name = "ADDRESS_ID")
private Long id;
#Id
#Column(name = "ADDRESS_STREET")
private String street;
#OneToOne
#JoinColumn(name = "PERSON_ID")
private Person person;
}
Also, we need to add the duplicate mapping association for the new entity.
#Entity
#Table(name = "PERSON")
public class Person {
#Id
#Column(name = "PERSON_ID")
private Long id;
#Id
#Column(name = "PERSON_NAME")
private String name;
#OneToMany(mappedBy = "person", fetch = FetchType.LAZY)
private Set<Address> addresses;
#OneToOne(mappedBy = "person")
private ShippingAddress shippingAddress;
}
Finally, you can use a join with this specific Entity in your criteria :
PersonRoot.join(Person_.shippingAddress, JoinType.LEFT);
The Hibernate Snippet SQL should seems like this :
left outer join
address shippingadd13_
on person11_.person_id=shippingadd13_.person_id
and (
shippingadd13_.ADDRESS_TYPE_ID = 2
)
ON clause is supported in Hibernate 4.3 version, anyone is aware if there is a parameter indexing issue between the parameter index of the additional custom conditions with the index of the existing mapping filters when doing an outer join with ON clause?
Using the Person entity class below as an example, say I am adding this filter to limit the address types and the filter is enabled to populate the IN clause. The parameter index for the IN clause will cause the issue [2] when I add additional conditions (such as using 'street' column) part of the ON clause. Is is a known issue?
[1] #Filter(name = "addressTypes", condition = "ADDRESS_TYPE in (:supportedTypes)")
[2]
Caused by: ERROR 22018: Invalid character string format for type BIGINT.
private Set addresses;