Use an object stored in objectdb file without having it's class definition

Question

Let's say I create an object in java named Point with 2 attributes (int x & int y) and i store some instances in an objectdb file. I know how to retrieve all items (as objects) from that file but how can I access their attributes if I don't have the definition of the class Point anymore?

Point definition

Class Point {
    int x;
    int y;
}

Then I create 2 Points (0,0) (1,1) and store them in objectdb file (i can provide the code if needed)

I retrieve all Point instances with this statement

     TypedQuery<Object> query = em.createQuery("SELECT o FROM Object o", Object.class);
     List<Object> results = query.getResultList();

Supposedly i only have the objectdb file and not the Point class definition how can i get the values of x and y (even as simple string values)?

Thanks in advance

Only way is to hack your way through the binary serialized version — ControlAltDel, Sep 10 '14 at 15:03
So an objectdb file is pretty much useless if it stands alone? — AkiS, Sep 10 '14 at 15:06
The comments above are incorrect. The data can be accessed by reflection. — ObjectDB, Sep 10 '14 at 18:04

score 0 · Answer 1 · answered Sep 10 '14 at 17:03

When a class definition is missing ObjectDB automatically generates a synthetic class according to the class schema as stored in the database. Therefore the query in your example returns instances of a synthetic Point class generated by ObjectDB.

You can access your data using the Java Reflection API (possibly using also the JPA Metamodel API).

Use an object stored in objectdb file without having it's class definition

1 Answers1