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Quarkus with Panache getting hibernate error HHH000183

I built an application with Quarkus and I'm using Hibernate with Panache for the models. Everything goes well, the application starts, but when I call a webservice to get a list using Panache functionalities (.listAll()), I get an empty list and I see the following message in the console:
HHH000183: no persistent classes found for query class: from com.myproject.model.TeamEntity
My models are defined with #Entity annotations that should allow Hibernate to find by itself the entity mappings. Here is an example with the Team model:
#Entity
#Table(name = "TEAM")
public class TeamEntity extends PanacheEntityBase {
#Id
#GeneratedValue(strategy = SEQUENCE, generator = "TEAM_SEQ_GEN")
#SequenceGenerator(name = "TEAM_SEQ_GEN", sequenceName = "TEAM_SEQ", allocationSize = 10)
#Column(name = "ID_TEAM", nullable = false)
private int id;
#Column(name = "NAME", nullable = false)
private String name;
...
}
I don't have any persistence.xml file in the project, only the application.properties linked with Quarkus. Here are the relevant properties extracted from mine:
quarkus.datasource.db-kind=oracle
quarkus.datasource.jdbc.url=jdbc:oracle:thin:/#MYWALLET
%dev.quarkus.datasource.jdbc.url=jdbc:oracle:thin:MYUSER/MYPASSWORD#localhost:1521/SAA
quarkus.datasource.jdbc.driver=oracle.jdbc.OracleDriver
quarkus.datasource.jdbc.min-size=2
quarkus.datasource.jdbc.max-size=10
quarkus.datasource.jdbc.new-connection-sql=alter session set current_schema=MYSCHEMA
quarkus.hibernate-orm.dialect=org.hibernate.dialect.Oracle12cDialect
Does someone know where the problem could come from ? Hibernate should detect entities with annotations and use them in queries automatically.

It came out that the problem was on Quarkus Datasource configuration in the application.properties file. More particularly from this specific line to define the schema used at first connection (I have to admit that was not good looking):
quarkus.datasource.jdbc.new-connection-sql=alter session set current_schema=MYSCHEMA
Replacing the line above with the following solved the problem:
quarkus.hibernate-orm.database.default-schema=MYSCHEMA
In conclusion, I think Hibernate cannot find / does not take the entities defined if this property is not defined, maybe because it makes some kind of detection beforehand. That's only a supposition, if someone knows more precisely how Hibernate works for that specific case, I would be very interested !

JPA #Column definition does not apply to read operations?

Given I have entity Car with column model which doesn't accept NULLs
#Table(name = "CAR")
#Entity
public class Car extends AbstractEntity<Long> {
#Column(name = "MODEL", nullable = false)
private final String model;
}
When I prepare database schema, insert data (including NULLs in MODEL column) manually and start up application, it doesn't fail to start.
Why is that?
Do conditions specified in #Column annotation only apply for insert/update operations, not for read operations?

Yes, you can read null values with nullable = false. But when you try to save or update an entity with model = null, the JPA lever error will be thrown.
Check out the specification for nullable.
This JPA constraints just prohibit non-valid data from being written to the database, in order not to call it for no reason (by the way, you should have the same constraints in your database as you have in JPA).
These constraints have nothing to do with data that is already there. So that's why your application doesn't fail to start.
Have a look at this answer for better explanation.

Hibernate JPA uniqueness

Let's say that this is a class that has unique constrained field.
#Entity
public class Thing {
#Column(name = "name", unique = true)
private String name;
#ManyToOne
private Owner owner;
}
Example works just fine if new Things are created with unique names. But when different owners want to create things with the same name this approach fails.
Is it possible to set unique constraint to differ records of Things in the database based on the Owners using Hibernate/JPA functionalities (I could not find any) or should I write my own logic and dump the unique from #Column.
Perhaps it could be done with Hibernate Validator? Reading the docs I haven't found much about unique constraints.

You're looking for #UniqueConstraint
http://docs.oracle.com/javaee/5/api/javax/persistence/UniqueConstraint.html

Getting Javassist types instead of actual Hibernate entity types

I have stumbled upon a really annoying situation: I am using Hibernate & Spring as backend for my app and it seems that in some cases, the entities that are in a relationship with a particular entity are not fetched as normal entity objects from the DB, but as Javassist types. E.g.:
I have the Campaign entity with the following relationships:
#Entity
#Table(name = "campaign")
public class Campaign implements Serializable {
[..]
#ManyToMany(fetch = FetchType.LAZY)
#JoinTable(uniqueConstraints = #UniqueConstraint(columnNames = {
"campaign_id", "dealer_id" }), name = "campaign_has_dealer", joinColumns = { #JoinColumn(name = "campaign_id", nullable = false) }, inverseJoinColumns = { #JoinColumn(name = "dealer_id", nullable = false) })
private List<Dealer> dealers = new ArrayList<Dealer>();
#ManyToMany
// (fetch = FetchType.LAZY)
#JoinTable(uniqueConstraints = #UniqueConstraint(columnNames = {
"campaign_id", "sales_area_id" }), name = "campaign_has_sales_area", joinColumns = { #JoinColumn(name = "campaign_id", nullable = false) }, inverseJoinColumns = { #JoinColumn(name = "sales_area_id", nullable = false) })
private List<SalesArea> salesAreas = new ArrayList<SalesArea>();
}
Upon retrieving the salesAreas connected to this Campaign, I get a list of SalesArea_$$_javassist_56, while for the dealers, I get normal Hibernate entities. Since the client part is based on GWT, we use RequestFactory for retrieving stuff. I initially thought it was a problem with the proxies, locators and so on but I have set a breakpoint in the service where these are retrieved and they are Javassist objects directly after selecting them. It seems that even removing the FetchType.LAZY annotation (although definitely not a desirable solution), the same thing happens. This happened also with other types of relationships, not only #ManyToMany.
We are using GWT 2.3, Spring 3, Hibernate 3.6.3 and JPA 2.0 for annotations.
Any suggestions would be appreciated.
Thanks in advance

As far as I can see the big problem that you're having is not so much the fetch type of your association, but rather that the proxied types don't work well with RequestFactory.
Yes, it could be solved by changing the fetch strategy but that sounds rather like a weak workaround that may break upon weird circumstances.
I don't remember exactly how to solve it, but I did, and as far as I remember there was an extension point in the ServiceLayerDecorator class. Basically there you check if the object you're returning is a Hibernate proxy (check Hibernate and HibernateProxy classes) and then return the non-proxy type instead in ServiceLayerDecorator. (http://code.google.com/p/google-web-toolkit/issues/detail?id=6767)
As for your fetch strategy, I'd largely recommend #BatchSize(N) where N is big (maybe 1000), but this is an independent subject.
Good luck!

If you call to the static method:
HibernateProxyHelper.getClassWithoutInitializingProxy(entity);
you get the class of the proxied entity and the class itself if it wasn't proxied.

With Hibernate's proxy model and now with it's use of Javassist to help avoid the slower traditional Hibernate run time reflection operations things will never quite be as elegant as the clean, intuitive experience people who use full bytecode enhancement solutions like JDO implementations (eg DataNucleus) enjoy.
Personally I can never see the sense in persisting (pardon the pun) with solutions that cause so many problems and fill the web with questions about broken code that requires strange, unintuitive workarounds but still people do...
However, back to the question: one solution to your problem, if you're using JPA, is to use DataNucleus/JPA which brings many of the benefits of DataNucleus/JDO (clean underlying implementation - no proxies, no Javassist classes etc.,) in a JPA compliant implementation - i.e. you don't need to change your existing source code to start using it.

Using unique constraint on Hibernate JPA2

How can I implement my unique constraints on the hibernate POJO's? assuming the database doesn't contain any.
I have seen the unique attribute in #Column() annotation but I couldn't get it to work?
What if I want to apply this constraint to more than one column?

You can declare unique constraints using the #Table(uniqueConstraints = ...) annotation in your class
#Entity
#Table(uniqueConstraints=
#UniqueConstraint(columnNames = {"surname", "name"}))
public class SomeEntity {
...
}

Bascially, you cannot implement unique constraint without database support.
#UniqueConstraint and unique attribute of #Column are instructions for schema generation tool to generate the corresponsing constraints, they don't implement constraints itself.
You can do some kind of manual checking before inserting new entities, but in this case you should be aware of possible problems with concurrent transactions.
Therefore applying constraints in the database is the preferred choice.

In JPA2, you can add the Unique constraint directly to the field:
#Entity
#Table(name="PERSON_TABLE")
public class Person{
#Id
#Column(name = "UUID")
private String id;
#Column(name = "SOCIALSECURITY", unique=true)
private String socialSecurityNumber;
#Column(name = "LOGINID", unique=true)
private String loginId;
}
IMHO its much better to assign the unique constraint directly to the attributes than at the beggining of the table.
If you need to declare a composite unique key however, then declaring it in the #table annotation is your only option.