我尝试使用 Spring Boot + Spring Data JPA 更新实体已经有一段时间了。我得到了所有正确的观点。我的编辑 View 通过 ID 向我返回正确实体。一切都很好..直到我真正尝试保存/合并/保留对象。 每次 我用新 ID 取回一个新实体。我只是不知道为什么。我查看了在线示例以及您可能会向我推荐的重复问题的链接。那么我在这些代码中的什么地方犯了错误呢？
package demo;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name = "ORDERS")
public class Order {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Integer id;
@Column(name = "ORDER_NAME")
private String name;
@Column(name = "ORDER_DESCRIPTION")
private String description;
@Column(name = "ORDER_CONTENT")
private String content;
public Order() {}
public Order(String name, String description, String content) {
this.name = name;
this.description = description;
this.content = content;
}
public String getContent() {
return content;
}
public String getDescription() {
return description;
}
public String getName() {
return name;
}
public Integer getId() {
return this.id;
}
public void setContent(String content) {
this.content = content;
}
public void setDescription(String description) {
this.description = description;
}
public void setName(String name) {
this.name = name;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Order other = (Order) obj;
if (content == null) {
if (other.content != null)
return false;
} else if (!content.equals(other.content))
return false;
if (description == null) {
if (other.description != null)
return false;
} else if (!description.equals(other.description))
return false;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
return true;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((content == null) ? 0 : content.hashCode());
result = prime * result
+ ((description == null) ? 0 : description.hashCode());
result = prime * result + ((id == null) ? 0 : id.hashCode());
result = prime * result + ((name == null) ? 0 : name.hashCode());
return result;
}
@Override
public String toString() {
return "Order [id=" + id + ", name=" + name + ", description="
+ description + ", content=" + content + "]";
}
}
package demo;
import org.springframework.data.jpa.repository.JpaRepository;
public interface OrderRepository extends JpaRepository<Order, Integer> {
public Order findByName(String name);
}
打包演示；
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.transaction.Transactional;
import org.springframework.stereotype.Service;
@Service("customJpaService")
public class CustomJpaServiceImpl implements CustomJpaService{
@PersistenceContext
private EntityManager em;
@Transactional
public Order saveOrUpdateOrder(Order order) {
if (order.getId() == null) {
em.persist(order);
} else {
em.merge(order);
}
return order;
}
}
打包演示；
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.support.RedirectAttributes;
@Controller
public class OrderController {
//refactor to service with
//logging features
@Autowired
OrderRepository orderRepo;
@Autowired
CustomJpaService customJpaService;
@RequestMapping(value="/orders", method=RequestMethod.GET)
public ModelAndView listOrders() {
List<Order> orders = orderRepo.findAll();
return new ModelAndView("orders", "orders", orders);
}
@RequestMapping(value="/orders/{id}", method=RequestMethod.GET)
public ModelAndView showOrder(@PathVariable Integer id, Order order) {
order = orderRepo.findOne(id);
return new ModelAndView("showOrder", "order", order);
}
@RequestMapping(value="/orders/edit/{id}", method=RequestMethod.GET)
public ModelAndView editForm(@PathVariable("id") Integer id) {
Order order = orderRepo.findOne(id);
return new ModelAndView("editOrder", "order", order);
}
@RequestMapping(value="/updateorder", method=RequestMethod.POST)
public String updateOrder(@ModelAttribute("order") Order order, BindingResult bindingResult, final RedirectAttributes redirectattributes) {
if (bindingResult.hasErrors()) {
return "redirect:/orders/edit/" + order.getId();
}
customJpaService.saveOrUpdateOrder(order);
redirectattributes.addFlashAttribute("successAddNewOrderMessage", "Order updated successfully!");
return "redirect:/orders/" + order.getId();
}
@RequestMapping(value="/orders/new", method=RequestMethod.GET)
public ModelAndView orderForm() {
return new ModelAndView("newOrder", "order", new Order());
}
@RequestMapping(value="/orders/new", method=RequestMethod.POST)
public String addOrder(Order order, final RedirectAttributes redirectAttributes) {
orderRepo.save(order);
redirectAttributes.addFlashAttribute("successAddNewOrderMessage", "Success! Order " + order.getName() + " added successfully!");
return "redirect:/orders/" + order.getId();
}
}
在这段代码之后。我的 View 将我返回到正确的 URL，但 ID 为 4 <-- 这是一个新实体。它应该说 3 具有更新的属性。
最佳答案
您需要将实体存储在 GET 请求和 POST 请求之间的某处。您的选择:
- 在 POST 开始时从数据库重新加载实体，并从 POST 实体复制其属性
- 将实体信息存储在隐藏的表单变量中
- 在 session 中存储实体
3 是最简单的解决方案，因为它允许乐观的并发控制，并且比隐藏形式的变量更安全。
如果你对隐藏的表单变量进行 HMAC 并检查它是否正确，2 会很好
在您的 Controller 顶部添加 @SessionAttributes("modelAttributeName")，并将 SessionStatus 参数添加到您的 POST 处理程序方法。完成后调用 sessionStatus.setComplete()。参见 Spring MVC: Validation, Post-Redirect-Get, Partial Updates, Optimistic Concurrency, Field Security一个工作示例。
关于java - Spring Data JPA 合并更新的实体，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/32021049/