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Hibernate 5.2 get natural id properties from metamodel

Since SessionFactory#getClassMetadata(java.lang.Class) was deprecated, I am not able to use ClassMetadata. I would like to access to the following methods:
org.hibernate.metadata.ClassMetadata#getNaturalIdentifierProperties
org.hibernate.metadata.ClassMetadata#hasNaturalIdentifier
According to the documentation, I should replace getClassMetada with EntityManagerFactory.getMetamodel(). However, the metamodel does not contain methods to get natural-id. I am using xml mapping for natural-id and I would like to get the property names of the natural-id to create a dynamic query.
<class name="User">
<cache usage="read-write"/>
<id name="id">
<generator class="increment"/>
</id>
<natural-id>
<property name="name"/>
<property name="org"/>
</natural-id>
<property name="password"/>
</class>
Is there a way to use those methods to get the natural id mapping?
Is there another way to get a ClassMetadata instance?
Is it possible to get an instance of entityMetamodel to replace the ClassMetadata?

Well, knowing that SessionFactory#getClassMetadata(java.lang.Class) was deprecated, the option is using sessionFactory.getMetamodel(). Checking into hibernate code, this was my solution:
MetamodelImplementor metamodel = (MetamodelImplementor) sessionFactory.getMetamodel();
ClassMetadata classMetadata = (ClassMetadata) metamodel.entityPersister(entityName);
First, one part important to know is what entityName is. It could be the name of the mapped entity or Entity.class.getName(). Knowing that, to replace SessionFactory#getClassMetadata(java.lang.Class) with should get the name of the class and pass it as an string.
String entityName = EntityClass.class.getName();
Second, Hibernate has an implementation of JPA metamodel, named MetamodelImplementor.
Additionally, metamodel.entityPersister() returns an EntityPersister interface. Hibernate implements it using AbstractEntityPersister. And that is an abstract class which implements Lockable and ClassMetadata interfaces.
EntityPersister (interface) --> Lockable (interface) -->
AbstractEntityPersister (abstract class)
ClassMetadata (interface) --> AbstractEntityPersister (abstract class)
So, it is possible to cast AbstractEntityPersister to ClassMetadata. And in that way return same object.
This is a portion of code of Hibernate in SessionFactoryImpl:
public ClassMetadata getClassMetadata(String entityName) throws HibernateException {
return (ClassMetadata) getMetamodel().entityPersister( entityName );
}

Strange behaviour with composite-id and version in hibernate 3.6

I encounter strange behaviour on Hibernate's merge() if I use an entity with a composite-id and a version number.
This is my hibernate mapping file:
<class name="ArticleTurnover" table="T_ARTICLETURNOVER">
<composite-id>
<key-property name="mainArticleId" type="java.lang.Integer" column="ARTICLETURNOVER_ID"/>
<key-property name="locationId" type="java.lang.Integer" column="ARTICLETURNOVER_LOCATIONID"/>
</composite-id>
<version name="version" column="ARTICLETURNOVER_VERSION" />
... some properties
</class>
And this is the code (it fails...):
ArticleTurnover at = new ArticleTurnover();
at.setMainArticleId(1);
at.setLocationId(1);
ArticleTurnover savedAt = em.merge(at);
assertNotNull(savedAt.getMainArticleId());
assertNotNull(savedAt.getLocationId());
After calling merge the fields mainArticleId and locationId are both null. The code above is just a test, but if I would commit a transaction, hibernate would insert null into the composite-id fields, and fail!
If I change em.merge(at) to em.persist(at) everything works. And if I manually set at.setVersion(0) (!!) it also works.
I ended up in adding a component type ArticleTurnoverId for my composite-id like mentioned here: http://docs.jboss.org/hibernate/core/3.6/reference/en-US/html/mapping.html#d0e4819.
Can anybody tell me what I am doing wrong, or point out why this happens?

Hibernate retrieves many-to-one without asking

we have a big problem in our development team.
We are using Hibernate and we have some entities which are related in two transitive one-to-many relations. The main object is a Group which has a list of Property instances, and each Property containing a list of Values.
(The mappings are down ahead)
We have two main problems:
A) When making a HQL Query, Criteria Query or SQLQuery it doesn't matter the conditions applied in JOINs or WHERE clauses, Hibernate always retrieves for us all the underlying objects. For example, if I make a Criteria or SQL getting only the Group objects, Hibernate comes and (lazy or not) gets all the Property and Value instances too. We want to control this. We want to do left joins and get only the properties with no values inside (Hibernate removes these properties with no value)
B) When making the Query, for example, a SQL, it shows in the log the SQL code we want. Everything seems perfect. But after that it brings every instance in the list without applying conditions, getting them only by id, and we can assure this because with lazy="true" we see the "load many-to-one" queries in the log.
Is there something we can do in hibernate config, fetching mode/strategy, the mappings configuration or anywhere? I'm thinking on going on Result transformers now.
I would be grateful if someone coud give me a hint or tell me where to find a solution to this problem. We are confused about how to get this, but it must be a way.
Thanks in advance
Query:
Criteria lstCriterios = this.getSession().createCriteria(CardGroup.class, CARD_GROUP)
.add(Restrictions.eq(ID_CATEGORY, idCategory));
lstCriterios.createAlias("listProperty", "listProperty", CriteriaSpecification.LEFT_JOIN);
if (clusterId != null) {
lstCriterios.add(Restrictions.or(
Restrictions.isNull("listPropertyValue" + ".value"),
Restrictions.and(Restrictions.eq("listPropertyValue" + ".clusterId", clusterId),
Restrictions.eq("listPropertValue" + ".companyWarehouseId", idCompanyWarehouse))));
lstCriterios
.createAlias("listProperty" + "." + "listPropertyValue", "listPropertyValue",
CriteriaSpecification.LEFT_JOIN,
Restrictions.eq("listPropertyValue" + ".clusterId", clusterId));
} else {
lstCriterios.createAlias("listProperty" + ".listPropertyValue", "listPropertyValue",
CriteriaSpecification.LEFT_JOIN);
}
lstCriterios.add(Restrictions.eq(ID_CATEGORY, idCategory));
lstCriterios.add(Restrictions.eq("listProperty" + ".groupId", idGroup));
lstCriterios.setResultTransformer(CriteriaSpecification.DISTINCT_ROOT_ENTITY);
/*
* Sorting
*/
lstCriterios.addOrder(Order.asc("order"));
lstCriterios.addOrder(Order.asc("listProperty" + ".order"));
lstCriterios.addOrder(Order.asc("listPropertyValue"+ ".clusterId")); // Agrupacion, podría ser nulo
lstCriterios.addOrder(Order.asc("listPropertyValue"+ ".propertyId")); // Propiedad
lstCriterios.addOrder(Order.asc("listPropertyValue"+ ".id"));
return lstCriterios.list();
Group mapping:
<list name="listProperty"
table="FICHA_PROPIEDAD" schema="${db2.siglo.schema}"
inverse="false" cascade="all" >
<key column="ID_FICHA_GRUPO" not-null="false" />
<list-index column="ORDEN" base="1"/>
<one-to-many
class="com.company.aslo.appwebsiglo.model.card.property.property.CardProperty" />
</list>
Property mapping:
<bag name="listPropertyValue"
table="FICHA_PROPIEDAD_VALOR" schema="${db2.siglo.schema}"
inverse="false" cascade="all">
<key column="ID_FICHA_PROPIEDAD" not-null="false" />
<one-to-many
class="com.company.aslo.appwebsiglo.model.card.propertyvalue.propertyvalue.CardPropertyValue" />
</bag>

It seems like our model design was bad and we didn't realize that if the DB table FICHA_PROPIEDAD_VALOR has Composite Key we can't map only one of the attributes in the composite key, because it brings us unexpected results.
Because of this and the nested objects, we had also bad implementations of the hashCode() and equals() methods which Hibernate uses.
I had solved this previously with a ResultTransformer getting the rows from a SQLQuery, but we got the Hibernate solution after that refactoring and changing the design of our model.

Hibernate mapping with one-to-many polymorphic relationship

I have the following class diagram and I want to map it to a database (note that Person has a list with objects of class Vehicle).
Also my database looks like:
All tables in the database that represent a subclass of the Vehicle class have all the fields of the superclass Vehicle. Also, all the relations show a one-to-many relationship from Person to Vehicle, Car and Motorcycle.
My hibernate mapping files are the following:
Person.hbm.xml
<hibernate-mapping package="....">
<class name="Person" table="Persons">
<id name="key" column="Person_ID">
<generator class="native"/>
</id>
<list name="ownedVehicles" inverse="false" cascade="all">
<key column="Person_ID" not-null="true" />
<list-index column="idx"/>
<one-to-many class="Vehicle"/>
</list>
</class>
</hibernate-mapping>
Vehicle.hbm.xml
<hibernate-mapping package="...">
<class name="Vehicle" table="Vehicles" polymorphism="implicit">
<id name="id" type="int" column="Vehicle_ID">
<generator class="increment"/>
</id>
<property name="numOfSeats"/>
<union-subclass name="Car" table="Cars"></union-subclass>
<union-subclass name="Motorcycle" table="Motorcycles"></union-subclass>
</class>
</hibernate-mapping>
The problem (error I get) is the following:
Hibernate: insert into Persons (Person_ID) values (default)
2013-06-26 15:41:52 WARN JdbcCoordinatorImpl:424 - HHH000386: ResultSet had no statement associated with it, but was not yet registered
Hibernate: update Car set numOfSeats=? where Vehicle_ID=?
org.hibernate.StaleStateException: Batch update returned unexpected row count from update [0]; actual row count: 0; expected: 1
I get this error when I run:
Car car = new Car();
car.setNumOfSeats(5);
Person person = new Person();
person.getOwnedVehicles().add(car);
ManagePerson managePerson = new ManagePerson();
Integer personID = managePerson.store(person);
The store() function of ManagePerson actually creates a session and a transaction and then uses the save() method provided by Hibernate to persist the objects into the database.
As far as I understand Hibernate usually will do insert into Persons, then insert into Cars and finally update Cars (the update is done to save the foreign keys on Cars table that will reference the Person that owns the cars). However, here this is not the case and the insert into Cars seems to be getting skipped. I understood how Hibernate works here by trying person.getOwnedVehicles().add(vehicle); instead of person.getOwnedVehicles().add(car); on the code given above.
As you might understand, I am trying to see if Hibernate actually understands in which "subclass" table a record should go, depending on the class of the object contained in the ownedVehicle list of the Person class. For example, if the ownedVehicles has an object of class Car and one of class Motorcycle, then each of these should go to Cars and Motorcycle tables respectively.
Note: I am using Hibernate 4.2.2 and HSQLDB 2.2.9.
I would appreciate any help with this.
Thanks.

I think it is just a matter of incorrect use of the implicit polymorphism of Hibernate.
Implicit polymorphism for your case can only work by changing your list to have
inverse="true". This can be done of course if your Vehicle class also 'knows' about the relationship with the Person class (e.g. by adding an 'Owner' property and the corresponding mapping).
(Have a look at this table and the case of "table per concrete-class (union-subclass)" and one-to-many associations.
If you enable logging and raise the log level to DEBUG you would see that currently Hibernate tries to update the Vehicles table with the Person_ID instead of the Car table like you meant it to. This is because of the inverse="true" and the limitations of the combination of the Table-per-concrete-class mapping strategy and implicit polymorphism (have a look at the documentation).
So, by having the Vehicle class know about its Owner and using inverse="true" you should be able to succeed in what you are trying to do. Either this or try one of the other inheritance mapping strategies (again have a look at the documentation).

If the managePerson.store(...) method doesn't have a recursive call to the objects in "getOwnedVehicles()" such that it can then call their "store" methods then you shouldn't expect that the created "car" object would be inserted into the table.
You are in fact calling "managePerson.store" not "manageCar.store", I'd have to see the code in the .store(...) method to be sure though but I would expect that it is not doing an iteration of the Vehicles and is not doing an insert for any discovered ones (why should it unless you built it explicitly to do that?).

how to define an inverse cascade delete on a many-to-one mapping in hibernate

I have two classes A and B. Many B's can have association with a single A, hence a many-to-one relationship from B to A. I've mapped the relationship like:
<class name="A" table="tbl_A">
<property name="propA" column="colA"/>
</class>
<class name="B" table="tbl_B">
<property name="propB" column="colB"/>
<many-to-one name="a" class="A" column="col1" cascade="delete"/>
</class>
A has nothing mapped to B. Keeping this in mind we intend to delete B when it's associated A is deleted. This could have been possible if I could define an inverse="true" on the many-to-one association in B but hibernate does not allow that.
Can anyone help with this? We do not want to write anything in A for this.

Hibernate only cascades along the defined associations. If A knows nothing about Bs, nothing you do with A will affect Bs.
Pascal's suggestion is, therefore, the easiest way to do what you want:
<class name="A" table="tbl_A">
...
<set name="myBs" inverse="true" cascade="all,delete-orphan">
<key column="col1"/>
<one-to-many class="B"/>
</set>
</class>
<class name="B" table="tbl_B">
...
<many-to-one name="a" class="A" column="col1" not-null="true"/>
</class>
Note that setting cascade="delete" on B as you have it in your original code will NOT do what you want - it tells Hibernate to "delete A if B is deleted" which is likely to result in constraint violation (if there are any other Bs linked to that A).
If you absolutely cannot add a collection of Bs to A (though I can't really think of the circumstances where that'd be the case), your only other alternative is to define cascade delete from A to B at the foreign key level; your Bs will then be deleted when your A is deleted.
This is a rather ugly solution, however, because you have to be extremely careful of how you delete A in Hibernate:
Session must be flushed prior to deleting A (having pending updates to B may result in an error or A and some Bs being re-inserted behind the scenes)
All Bs linked to your A (and since you're not maintaining the relationship from A side that means all Bs) must be evicted from all active sessions and 2nd level cache.

I think you need to cascade="all,delete-orphan" from A to B's with a one-to-many association.