我試圖理解為什么當我第二次點擊控制器時，我的 OnetoOne 映射正在初始化。下面是我的代碼：控制器：@RequestMapping(value="/updateOrderbyOrderid", method=RequestMethod.PUT,produces=MediaType.APPLICATION_JSON_VALUE)public Order updateOrderbyOrderid (@RequestBody Order orderVO ) {System.out.println(orderVO.getOrderId());Order s1 = orderRepository.findByOrderId(orderVO.getOrderId());if (orderVO.getCustomerId()!=null) { orderVO.setCustomer(customerRepository.findByCustomerId(orderVO.getCustomerId()));}s1 = orderRepository.saveAndFlush(orderVO);return s1;}訂單實體：@Entity@Table(name="Ordertable", schema="cf_2583f365_c3c6_499a_a60d_138e7e7023eb")public class Order {@Id@Column(name = "ORDER_ID")@GeneratedValue(strategy=GenerationType.IDENTITY)private int orderId;@OneToOne(fetch=FetchType.LAZY,cascade=CascadeType.ALL)@JoinColumn(name = "ORDER_CUSTOMER_ID", referencedColumnName = "CUSTOMER_ID")private Customer customer;private transient Long customerId;public int getOrderId() { return orderId;}public void setOrderId(int orderId) { this.orderId = orderId;}public Customer getCustomer() { return customer;}public void setCustomer(Customer customer) { this.customer = customer;}public Long getCustomerId() { return customerId;}public void setCustomerId(Long customerId) { this.customerId = customerId;}}客戶實體：@Entity@Table(name="Customer", schema="cf_2583f365_c3c6_499a_a60d_138e7e7023eb")public class Customer {@Id@Column(name = "CUSTOMER_ID")@GeneratedValue(strategy=GenerationType.IDENTITY)private Long customerId;@Column(name = "CUSTOMER_NAME")private String customer_name;@Column(name = "CUSTOMER_address_id")private int customer_address_id;public Long getCustomerId() { return customerId;}public void setCustomerId(Long customerId) { this.customerId = customerId;}public String getCustomer_name() { return customer_name;}public void setCustomer_name(String customer_name) { this.customer_name = customer_name;}public int getCustomer_address_id() { return customer_address_id;}
3 回答
catspeake
TA貢獻1111條經驗 獲得超0個贊
Spring Data JPAfindBy()方法由EntityManager.find(). EntityManager.find()首先檢查緩存中的數據，如果在緩存中沒有找到數據，則點擊數據庫加載數據并放入緩存以使其管理。
如果我們再次這樣做EntityManager.find()（再次針對相同的主鍵），它會再次檢查緩存。現在這一次數據是從緩存中加載而不是命中數據庫。
我認為 Hibernate 正在緩存對象，當我第二次點擊它時，它會返回緩存項的代理對象。
以下是我已閱讀以了解findBy()工作的鏈接。
使用 getOne 和 findOne 方法時 Spring Data JPA
EntityManager.find() 和 EntityManger.getReference() 有什么區別？
現在為了測試我是否正確，我em.detach()在下面的代碼中使用了。detach()將使托管實體 --> 非托管，并將其從緩存中刪除?，F在，當我執行代碼時，我得到了新初始化的 bean。
@RequestMapping(value="/updateOrderbyOrderid", method=RequestMethod.PUT,produces=MediaType.APPLICATION_JSON_VALUE)
public Order updateOrderbyOrderid (@Valid @RequestBody Order orderVO ) {
System.out.println(orderVO.getOrderId());
Order s1 = orderRepository.findByOrderId(orderVO.getOrderId());
em.detach(s1.getCustomer());
s1= null;
if (orderVO.getCustomerId()!=null) {
Customer findByCustomerId = customerRepository.findByCustomerId(orderVO.getCustomerId());
orderVO.setCustomer(customerRepository.findByCustomerId(orderVO.getCustomerId()));
}
s1 = orderRepository.saveAndFlush(orderVO);
return s1;
}
慕慕森
TA貢獻1856條經驗 獲得超17個贊
您的映射看起來很像多對多。試試這個：
// OrderTable
@OneToOne(fetch = FetchType.LAZY, optional = false)
@JoinColumn(name = "CUSTOMER_ID", nullable = false)
private Customer customer;
// constructors
public OrderTable() {}
public OrderTable(Customer customer) { this.customer = customer; }
// Customer
@OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL, mappedBy = "customer")
private OrderTable orderTable;
慕哥9229398
TA貢獻1877條經驗 獲得超6個贊
我認為您必須使用fetch=FetchType.EAGER進行 OneToOne 映射
@OneToOne(fetch=FetchType.EAGER,cascade=CascadeType.ALL)
@JoinColumn(name = "ORDER_CUSTOMER_ID", referencedColumnName = "CUSTOMER_ID")
private Customer customer;
希望它會有所幫助。
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