Question

最近我开始使用hibernate。插入或更新我正在使用saveOrUpdate()功能。如果我更新一个条目我工作正常。但是，用新的入口hibernate生成一个Query。但表中没有任何内容更新。

我的情况是这样的，

我正在使用Many to One＆amp;两个表之间的一对多关系[Expense, Category] 对于更新或插入，我正在创建两个对象(Expense expense, Category category) 客户端。在服务器端，我使用category对象设置expense对象。

public void upDateExpenseTable(Expens expense, Category category) {

    expense.setCategory(category);
    Session session = Main.getSession();
    try{
        System.out.println("Inside Update Try Block");
        session = Main.getSession();
        Transaction tr = session.beginTransaction();
        session.saveOrUpdate(expense);
        tr.commit();

    }
    finally{
        session.close();
    }
}

对象结构就像，catogery.catId, category.catName＆amp; expense.expnsId, expense.expnsName, expense.amount, expense.status, expense.userName。

但Expense表cat_id中还有另一列。它是通过映射注释。但我在Expense实体中没有任何财产。插入新数据时，我没有给出任何ID。

任何建议!!!

public class Expens implements Serializable {
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private int expnsId;
private int amount;
private String date;
private String status;
private String userName;

    @ManyToOne
@JoinColumn(name = "cat_id") 
private Category category;
    //Setter Getter

}

类别类

public class Category{
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private int catId;
private String catName;

@OneToMany(targetEntity=Expens.class, mappedBy = "category", cascade = CascadeType.ALL, fetch=FetchType.EAGER)
private List<Expens> expenses;
}//Setters Getters ommited.

Answer 1

我不确定我是否了解所有内容，但我至少可以告诉您，您没有正确构建双向关联，您需要设置“链接的两侧”时构建对象图：

...
expense.setCategory(category);
category.getExpenses().add(expense);
...
session.saveOrUpdate(category);

这通常在“链接管理”方法中完成，如下所示（在Category中）：

@Entity
public class Category {

    @Id @GeneratedValue(strategy=GenerationType.AUTO)
    private int catId;
    private String catName;

    @OneToMany(targetEntity=Expens.class, mappedBy = "category", cascade = CascadeType.ALL, fetch=FetchType.EAGER)
    private List<Expens> expenses = new ArrayList<Expens>();

    public void addToExpenses(Expense expense) {
        expenses.add(expense);
        expense.setCategory(this);
    }    

    protected List getExpenses() { // protected to prevent direct access from outside the hierarchy
        return expenses;
    }

    protected void setExpenses(List expenses) { // protected to prevent direct access
        this.expenses = expenses;
    }

    //...
}

代码变为：

category.addToExpenses(expense);
session.saveOrUpdate(category);

有趣（或没有），我今天已经写了三次。

资源

Hibernate核心文档
- 1.2.6. Working bi-directional links

hibernate中的saveOrUpdate（）问题

1 个答案:

资源