We have this relationship:
public class RuleProviderEntity implements Serializable
{
...
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
#OrderColumn(name = RuleEntity.RULE_SEQUENCE)
private List<RuleEntity> rules;
}
This alone creates a join table with 2 keys and the RULE_SEQUENCE column. So far good and works for SELECTs.
Now there's a JQL query
DELETE FROM RuleProviderEntity WHERE ...
But this fails to cascade deleting the RuleEntity rows. It just deletes the RuleProviderEntity and leaves the RuleEntity intact.
Is this supposed to work in JPA 2 and it's a Hibernate bug, or am I missing something in the config?
I know I could add #JoinTable but it would only override the defaults.
Also orphanRemoval seems not necessary here.
Maybe I could do a workaround with #PreRemove but not sure how.
You mean a JPQL Bulk Delete query is issued? rather than em.remove().
A Bulk Delete query will NEVER respect cascade semantics and is not intended to (nor will it keep managed objects in-memory consistent with the datastore). If you want cascading then you need to call em.remove(). If in doubt about this look at the JPA spec.
Related
I'd like to optimize a queryDSL + Spring data query. Currently I am using a BooleanBuilder as the predicate, which would be fine, but it joins too many tables. I don't need all the columns from the tables and I don't need some of the tables at all. I believe using a projection would reduce the number of tables joined.
I tried with using a Projections.bean() and also with extending MappingProjection, but both approaches result in not using joins but selecting from multiple tables which results in less rows than what's needed.
My data structure consists of a Booking entity and some related entites like User, so looks something like the following:
#Entity
public class Booking {
#ManyToOne
#JoinColumn(name = "userId", nullable = false)
private User endUser;
}
#Entity
public class User {
#OneToMany(cascade = CascadeType.ALL, mappedBy = "endUser", fetch = FetchType.LAZY)
private List<Booking> bookings;
}
I implemented a custom queryDSL projection repository as described here: Spring Data JPA and Querydsl to fetch subset of columns using bean/constructor projection
I'm trying a projection like the following:
Projections.bean(Booking.class,
booking.uuid,
Projections.bean(User.class,
booking.endUser.uuid
).as(booking.endUser.getMetadata().getName()
);
The sql generated by the current solution looks something like this:
select (...)
from booking booking0_,
user user12_
where booking0_.user_id=user12_.id
So, how can I make QueryDSL join the tables instead of selecting from all of them?
Am I on the right path to try to optimize the query? Does the projection make sense?
I ended up creating a DB view, making an Entity for it and then querying that with querydsl. This is really simple, straightforward and the performance is good too.
This is probably where ORMs are just not capable enough.
I have been getting an error while trying to update a list of entities containing persisted entity and detached entity both (newly created entity) into my db using jpa2.0.
My entity contains internal entities which are giving an error (mentioned in the title) when merging the data:
Class superclass{
private A a;
private string name;
//getter setters here...
}
Class A{
private long id;
#onetoone(cascade=CascadeType.All, fetch=FetchType.Eager)
private B b;
#onetoone(cascade=CascadeType.All, fetch=FetchType.Eager)
private C c;
//getter setters here...
}
Class Dao{
daoInsert(superclass x){
em.merge(x);
}
}
I want any entity sent for persisting to be merged into the db.
Hibernate does provide solution for this by adding the following to the persistence.xml
Is there something I can do in jpa same as hibernate.
Please do not suggest to find the entity using em.find() and then update manually because I need both entities the persisted entity and the newly created entity too.
Also I'm using spring form to persist the entire patent entity into db.
I am sorry if I'm not clear enough, this is my first question and I'm really a beginner.
Any help will be most appreciated.
Found an answer to the question myself today.You just need to
remove CascadeType.MERGE from the entity that is not allowing you to persist the detached entity.
if you're using CascadeType.ALL then mention all cascade type other than CascadeType.MERGE.
Now removing CascadeType.MERGE from cascade is one solution but not a best solution because after removing MERGE from Cascade you won't be able to update the mapped object ever.
If you want to merge the Detached entity with Hibernate then clear the entity manager before you merge the entity
entityManager.clear();
//perform modification on object
entityManager.merge(object);
To solve this problem make sure to specify that the identifiers of your objects are automatically generated by adding #GeneratedValue(strategy = GenerationType.IDENTITY) on the identifaint such as id.
In this way when the merge will be carried out, the identifier of the elements to merge will be automatically incremented, compared to the other object already recorded in the database to avoid primary key conflicts
Say i have class called Record, with a many-to-one relationship to a class called Artist.
If i define a cascade option as such:
class Record{
#ManyToOne(cascade = CascadeType.ALL)
private Artist artist;
...
}
Say i have a number of records managed by my EntityManager and some of these share the same Artist.
What happens when i call, update, merge, detach, remove and so on on the Record objects?
Will the artist be removed for example? Will it be detached? If so, what happens to the other Record classes that references that Artist?
Since you configured the association with cascade = CascadeType.ALL, all the operations done on a record will also be done on the associated Artist. Removing the record will thus remove the artist. This will fail with a foreign key constraint exception (if they're correctly configured in the database) if another record also references the same artist.
Configuring such a cascade on a ManyToXxx associations doesn't make much sense.
I have a many-to-many relationship where the link table has an additional property. Hence the link table is represented by an entity class too and called Composition. The primary key of Composition is an #Embeddable linking to the according entities, eg. 2 #ManyToOne references.
It can happen that a user makes an error when selecting either of the 2 references and hence the composite primary key must be updated. However due to how JPA (hibernate) works this will of course always create a new row (insert) instead of an update and the old Composition will still exist. The end result being that a new row was added instead of one being updated.
Option 1:
The old Composition could just be deleted before the new one is inserted but that would require that the according method handling this requires both the old and new version. plus since the updated version is actually a new entity optimistic locking will not work and hence last update will always win.
Option 2:
Native query. The query also increments version column and includes version in WHERE clause. Throw OptimisticLockException if update count is 0 (concurrent modification or deletion)
What is the better choice? What is the "common approach" to this issue?
Why not just change the primary key of Composition to be a UID which is auto-generated? Then the users could change the two references to the entities being joined without having to delete/re-create the Composition entity. Optimistic locking would then be maintained.
EDIT: For example:
#Entity
#Table(name = "COMPOSITION")
public class Composition {
#Id
#Column(name = "ID")
private Long id; // Auto-generate using preferred method
#ManyToOne(fetch = FetchType.LAZY, optional = false)
#JoinColumn( .... as appropriate .... )
private FirstEntity firstEntity;
#ManyToOne(fetch = FetchType.LAZY, optional = false)
#JoinColumn( .... as appropriate .... )
private SecondEntity secondEntity;
....
After struggling for days attempting to get back collections that are linked to a table via a foreign key, I just realized that the tables I am linking to are actually LINKING tables to other tables with the actual data (chock one up for normalized tables).
I am still struggling to get collections out of ManyToOne annotated variables with references to foreign keys, but is there a way I can pull the data back from the table that actually contains the information? Has anyone run into an instance of this?
UPDATE: AS per request I will be posting some code instances... This would be my named query in the entity that I will be calling...
#NamedQuery(name="getQuickLaunchWithCollections", query = "SELECT q FROM QuickLaunch q LEFT JOIN FETCH q.quickLaunchDistlistCollection LEFT JOIN FETCH q.quickLaunchPermCollection LEFT JOIN FETCH q.quickLaunchProviderCollection")})
These would be the collections that I am looking to fill...
#OneToMany(mappedBy="quickLaunchId", fetch=FetchType.EAGER)
private List<QuickLaunchPerm> quickLaunchPermCollection;
#OneToMany(mappedBy="quickLaunchId", fetch=FetchType.EAGER)
private List<QuickLaunchProvider> quickLaunchProviderCollection;
#OneToMany(mappedBy="quickLaunchId", fetch=FetchType.EAGER)
private List<QuickLaunchDistlist> quickLaunchDistlistCollection;
As you can see, I have the fetch type set to eager. So technically, I should be getting some data back? But in actuality those are just linking tables the data that I actually want to pull back. I will need to figure out how to get that data back eventually.
This is how I am calling that named query...
listQL = emf.createNamedQuery("getQuickLaunchWithCollections").getResultList();
Alright, it appears as though LEFT JOIN FETCH
is causing my runtime to throw an expception of some kind. It is pretty unclear as to what it is. But I feel as though I am getting no where with that technique. I am going to try something slightly different.
I would suggest simplifying example, to face the problem, since you are going worldwide now.
Specifying mappedBy="quickLaunchId" attribute, you are saying, that QuickLaunchPerm entity has QuickLaunch as its property named "quickLaunchId". Is this true?
If it is not, then you need to define it in QuickLaunchPerm:
#ManyToOne(fetch = FetchType.EAGER)
#JoinColumn(name = "QUICK_LAUNCH_ID")
private QuickLaunch quickLaunchId;
//getters setters