org.hibernate.PropertyAccessException: could not get a field value by reflection getter of

Question

I looked around for answers on this and it looks like it's something to do with reflections but since I haven't dealt with them I'm not sure how to proceed. I'm trying to build a HQL query that returns only rows from a table that match a column that is a FK to a PK in another table.

Here's what my code looks like:

Entity Book:

@Entity
@Table(name="book")
public class Book {

@Id
private String bookNumber;
private String bookName;
private String bookDescription; 
private double bookPrice;

@ManyToOne(cascade=CascadeType.ALL)
@JoinColumn(name="shelfnumber")
Shelf shelf;

Entity Shelf:

@Entity
@Table(name="shelf")
public class Shelf {

@Id
private String shelfNumber;

@OneToMany(mappedBy="shelf",cascade=CascadeType.ALL)
Set<Book> shelfBooks;

Note: both entity classes have getters/setters

ActionClass:

    DynaActionForm searchForm =((DynaActionForm)form);
    String shelfNum = searchForm.getString("shelfNum");

    SessionFactory sessionFactory = new   Configuration().configure().buildSessionFactory();
    Session session = sessionFactory.openSession();
    session.beginTransaction();

    try{
        session.getEntityMode();
        Query query = session.createQuery("FROM Book B WHERE B.shelf = :shelfNum"); //here is where the error happens: B.shelf is the problem but don't know why
        query.setParameter("shelfNum", shelfNum);
        List books = query.list();
        request.setAttribute("books", books);

    } finally{
        session.close();
    }

Error message I'm getting:

org.hibernate.PropertyAccessException: could not get a field value by reflection getter of com.library.entity.Shelf.shelfNumber

and further down I see:

Caused by: java.lang.IllegalArgumentException: Can not set java.lang.String field com.library.entity.Shelf.shelfNumber to java.lang.String

Thank you for any help!

Answer 1

Your query compares an instance of Shelf with an instance of String. That can't work. A Shelf is a Shelf. It's not a String.

The query should be

select b from Book b where b.shelf.shelfNumber = :shelfNum

Also, please tell me you don't actually recreate a SessionFactory at each and every request!

And please stop using raw types. We're not in 2003 anymore.