Question

好的开始：我在春天做药房项目。我正在使用Eclipse和Database PostgreSQL。

在数据库中我有表名：OrderItem，CustomerOrder，Product和Register（这是带有关于用户的传递和信息的类）。

好的，我想删除给定ID的CustomerOrder。

co.deleteCustomerOrder(co.getCustomerOrder(id));

如果我这样做了，我有这样的错误：

详细信息：Key（orderid）=（1421007984736）在表格中调用＆＃34; orderItem＆＃34; 错误：修改或删除表＆＃34;客户端＆＃34;违反外键＆＃34; fk60163f61b0099af4＆＃34;表＆＃34; orderitem＆＃34;

所以我首先添加了这个

 cos.deleteOrderItem(cos.getOrderItem(id))

然后

co.deleteCustomerOrder(co.getCustomerOrder(id));

现在我有这样的错误：

HTTP状态500 - 请求处理失败;嵌套异常是java.lang.IllegalArgumentException：尝试使用null实体创建删除事件

也许某些实体类存在问题：注册或其他。当我用PgAdminIII orderItem删除的方式当然我没有得到第一个错误，我可以完成这行代码

   co.deleteCustomerOrder(co.getCustomerOrder(id));

正常。

****如何解决第二个错误？我不想使用PgAdmin xD ****

我的一些代码。

package app.Spring.domain;



import java.util.Date;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

@Entity
@Table(name = "CustomerOrder")
public class CustomerOrder {

        @Id
        @Column(name = "orderID")
        private long orderID;

        @ManyToOne(cascade = { CascadeType.MERGE })
        private Register register;

        @Column(name = "status")
        private String status;

        @Column(name = "totalCost")
        private float totalCost;

        @Column(name = "orderDate")
        private Date orderDate;

        public CustomerOrder() {
        }

        public CustomerOrder(long orderID, Register register, String status,
                        float totalCost, Date orderDate) {
                this.orderID = orderID;
                this.register = register;
                this.status = status;
                this.totalCost = totalCost;
                this.orderDate = orderDate;
        }

        public long getOrderID() {
                return orderID;
        }

        public void setOrderID(long orderID) {
                this.orderID = orderID;
        }

        public Register getRegister() {
                return register;
        }

        public void setRegister(Register register) {
                this.register = register;
        }

        public String getStatus() {
                return status;
        }

        public void setStatus(String status) {
                this.status = status;
        }

        public float getTotalCost() {
                return totalCost;
        }

        public void setTotalCost(float totalCost) {
                this.totalCost = totalCost;
        }

        public Date getOrderDate() {
                return orderDate;
        }

        public void setOrderDate(Date orderDate) {
                this.orderDate = orderDate;
        }
}



package app.Spring.domain;
import java.util.List;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

@Entity
@Table(name = "OrderItem")
public class OrderItem {

        @Id
        @Column(name = "itemID")
        private long itemID;


        @ManyToOne(cascade = { CascadeType.MERGE })
        private Product product;

        @ManyToOne(cascade = { CascadeType.MERGE })
        private CustomerOrder customerOrder;

        @Column(name = "quantity")
        private int quantity;

        public OrderItem() {
        }

        public OrderItem(long itemID, Product product, CustomerOrder customerOrder,
                        int quantity) {
                this.itemID = itemID;
                this.product = product;
                this.customerOrder = customerOrder;
                this.quantity = quantity;
        }

        public long getItemID() {
                return itemID;
        }

        public void setItemID(long itemID) {
                this.itemID = itemID;
        }

        public Product getProduct() {
                return product;
        }

        public void setProduct(Product product) {
                this.product = product;
        }

        public CustomerOrder getCustomerOrder() {
                return customerOrder;
        }

        public void setCustomerOrder(CustomerOrder customerOrder) {
                this.customerOrder = customerOrder;
        }

        public long getQuantity() {
                return quantity;
        }

        public void setQuantity(int quantity) {
                this.quantity = quantity;
        }
}

控制器

@Controller
@RequestMapping("/admin/users")
public class AdminController {

    @Autowired
    LocalValidatorFactoryBean validator;

    @Autowired
    RegisterService reg;

    @Autowired    
CustomerOrderService co;
    @Autowired
OrderItemService cos;     

 @RequestMapping("/removecustomer/{id}")
    public String removeCustomerOrderById(@PathVariable Long id) {

        System.out.println("remove  customerOrderID "+id);
      cos.deleteOrderItem(cos.getOrderItem(id));
    co.deleteCustomerOrder(co.getCustomerOrder(id));


        return "redirect:/";
    }
}

CustomerOrderService

public class CustomerOrderImpl implements CustomerOrderService{


    protected final Logger log = LoggerFactory.getLogger(getClass());

    protected SessionFactory sessionFactory;

    public void setSessionFactory(SessionFactory sessionFactory) {
        this.sessionFactory = sessionFactory;
    }    

  @Override
      public CustomerOrder getCustomerOrder(Long id) {
          return (CustomerOrder)sessionFactory.getCurrentSession().get(CustomerOrder.class.getName(), id);
      }

 public void deleteCustomerOrder(CustomerOrder v) {
            sessionFactory.getCurrentSession().delete(v);
            sessionFactory.getCurrentSession().flush();
        }


}

OrderService

public class OrderItemImpl implements OrderItemService {



    protected final Logger log = LoggerFactory.getLogger(getClass());

    protected SessionFactory sessionFactory;

    public void setSessionFactory(SessionFactory sessionFactory) {
        this.sessionFactory = sessionFactory;
    }    



    public OrderItem getOrderItem(Long id) {
        return (OrderItem)sessionFactory.getCurrentSession().get(OrderItem.class.getName(), id);

    }
public void deleteOrderItem(OrderItem v) {
            sessionFactory.getCurrentSession().delete(v);
            sessionFactory.getCurrentSession().flush();
        }
}

Answer 1

cos.deleteOrderItem(cos.getOrderItem(id));
co.deleteCustomerOrder(co.getCustomerOrder(id));

表中的每个记录（行）都有一个键。您使用相同的密钥删除两个不同表中的项目。

除非它们恰好处于一对一的关系中，否则记录的ID不会反映这种关系。在这种情况下，您尝试使用未记录的密钥删除订单商品。

坦率地说：

您想要删除customerOrder 16;
您无法删除customerOrder 16;因为它有orderItems 4＆amp; 5由于外键而与之相关。
您正在尝试删除订单商品16;哪个不存在（第二个错误）。

正确的解决方案是：

将customerOrder和orderItems之间的关系设置为级联(cascade = {CascadeType.DELETE, CascadeType.MERGE})
在删除customerOrder之前，找到相关的orderItems并删除它们（再次，不同元素的关键字将不相关）。

如果您在理解密钥，外键和级联的概念时遇到问题，首先应该了解SQL的工作原理。

Answer 2

问题解决了:)

更改删除和更改查找相关orderItem的代码的方法。为了你，我应该学习更多SQL.This CascadeType.Remove不需要。

public void deleteOrderItem2(OrderItem orderItem) throws Exception {
      Session session=null;
      Transaction tx=null;
      try {
            session =     sessionFactory.openSession();
              tx=session.beginTransaction();
              orderItem = (OrderItem) session.merge(orderItem);
              session.delete(orderItem);
              session.flush();
              tx.commit();
      } catch (PersistenceException pe) {
              tx.rollback();
              throw pe;
      } finally {
              session.close();
      }

}

从数据库中删除表OrderItem

2 个答案: