CODEWITHSUNDEEP
javahibernatereflection
javiut
javiut

Reputation: 193

Java reflection superClass loaded by hibernate problems

I am trying to print in console the names of the fields of a superClass i needed for a later computing is working OK when is a simple POJO but when the class is previously loaded by Hibernate i am getting the fields of the child not the superClass and when i print the name of the parent (when loaded by Hibernate i am getting the following)

[handler,_filter_signature,serialVersionUID,methods]

here is my code

public static void main(String[] args)
{
    FixingModels clazz = new FixingModels();
    HibernateHandler handler = new HibernateHandler(true);
    Student student =  (Student)handler.getSession().load(Student.class,1);
    Student newStudent = new Student();
    System.out.println("Printing Class loaded by Hibernate");
    clazz.showFieldsFromSuperClass(student);//show the Fields of the Child and parent wrong
    System.out.println("--------------------------------------------------");
    System.out.println("Printing Class instance by new..");
    clazz.showFieldsFromSuperClass(newStudent);//Show the fields from the parent and child IS O.K
}
private void showFieldsFromSuperClass(Student clazz) 
{
    final Class objectClass = clazz.getClass();
    final Class parentClass = objectClass.getSuperclass();
    System.out.println("Printing Child");
    for(Field field:objectClass.getDeclaredFields())System.out.println(field.getName());//printing child
    System.out.println("Printing Parent");
    for(Field field:parentClass.getDeclaredFields())System.out.println(field.getName());//printing parent
}

the first time 

clazz.showFieldsFromSuperClass(student);

is called is printing [handler,_filter_signature,serialVersionUID,methods] later the the fields from the child is like the hibernate is now the parent of my student class not my abstract class in code. later

clazz.showFieldsFromSuperClass(newStudent);

is printing the right fields the student fields as well it's parent Person in this case

my question is how can i get the Person class fields[Parent Class] whenever comes from new instance of by hibernate or by Spring container??

Upvotes: 1

Views: 419

Answers (2)

dcernahoschi
dcernahoschi

Reputation: 15240

Hibernate load() method doesn't fully initialize the retrieved object, but returns a proxy until you access an object property.

You can get the correct Class of the object without initializing it using a special hibernate helper class:

HibernateProxyHelper.getClassWithoutInitializingProxy(student);

Upvotes: 1

Jon Skeet
Jon Skeet

Reputation: 1500845

Basically I suspect Hibernate is creating another subclass of your "child class" on the fly - and creating an instance of that when you fetch it from the session. Your code is currently relying on the instance being a direct instance of just Student.

This is easy to verify:

System.out.println("Instance class: " + objectClass);

I suspect what it prints is not what you're expecting to see.

Given that you know the parent class you want (the superclass of Student, presumably) why not just refer to that explicitly using a class literal?

Upvotes: 1

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