java - 组织.hibernate.PropertyAccessException : could not get a field value by reflection getter of

Question

我环顾四周寻找答案，看起来它与反射有关，但由于我没有处理过它们，所以我不确定如何进行。我正在尝试构建一个 HQL 查询，该查询仅返回表中与作为 FK 的列匹配的行到另一个表中的 PK。

这是我的代码:

实体书:

@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;

实体货架:

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

@Id
private String shelfNumber;

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

注意:两个实体类都有getters/setters

Action 类:

    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();
    }

我得到的错误信息:

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

再往下我看到:

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

感谢您的帮助!

Answer 1

您的查询将 Shelf 的实例与 String 的实例进行比较。那是行不通的。 Shelf 是一个 Shelf。它不是 String。

查询应该是

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

另外，请告诉我您实际上并没有在每次请求时都重新创建 SessionFactory!

请stop using raw types .我们已经不是 2003 年了。