java - 在具有多个 @ManyToOne 关联的实体上使用 hibernate update() 时，如何限制关联表被考虑加入

Question

我有一个 Record 实体，它与 Product_Category 表和 Price_Category 表保持 @ManyToOne 关系。记录实体还维护与另一个名为 PendingRecords 的表的 @OneToMany 关联。

目前，这对于 hibernate 保存/持久来说非常有效，其中当满足特定条件时，所有关联的表也会被修改。问题是这些关联实体也在 hibernate 更新/删除时得到考虑，这不是我想要做的。我想限制这些实体被考虑并仅允许在插入时进行更改。

以下是实体类映射

Record.java

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name = "ITEM_RECORDS")
public class Record {

-------------------------


@ManyToOne(optional=false)
@JoinColumn(name = "PRICE_CATEGORY", referencedColumnName="price_category", nullable=false)
private PriceCategory price_category;

@ManyToOne(optional=false)
@JoinColumn(name = "PRODUCT_CATEGORY", referencedColumnName="product_category", nullable=false)
private ProductCategory product_category;

@OneToOne(mappedBy="record", cascade = CascadeType.ALL)
private PendingRecords pendingRecord;

----------------------

(getter setter methods)

-----------------------

以下是相关表格

PriceCategory.java

@Entity
@Table(name = "PRICE_CATEGORY")
public class PriceCategory{

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

@Column(name = "PRICE_CATEGORY")
private String price_category;

@Column(name = "DESCRIPTION")
private String description;

----------------------------

 (getter-setters)

----------------------------

ProductCategory.java

@Entity
@Table(name = "PRODUCT_CATEGORY")
public class ProductCategory {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "ID")
private Long id;

@Column(name = "PRODUCT_CATEGORY")
private String product_category;

@Column(name = "DESCRIPTION")
private String description;

----------------------------

 (getter-setters)

----------------------------

最后，

PendingRecords.java

@Entity
@Table(name = "PENDING_RECORDS")
public class PendingRecords{


@Id
@Column(name = "PENDING_RECORD_NO")
@GeneratedValue(generator="gen")
@GenericGenerator(name="gen", strategy="foreign",parameters=@Parameter(name="property", value="record"))
private Long pending_record_id;

----------------------

@OneToOne
@PrimaryKeyJoinColumn
private Record record;

-------------------------

(getters-setters)

-------------------------

当我执行插入( hibernate 持久/保存)时，实体关联工作正常。问题是当我尝试更新记录时，hibernate 正在尝试更新所有关联的条目，就像

   select
   this_.RECORD_NO as REC_REC1_1_3_,

   this_.PRICE_CATEGORY as PRICE_CA10_1_3_,

   this_.PRODUCT_CATEGORY as PRODUCT11_1_3_,

   pricecatego2_.id as id1_0_0_,
   pricecatego2_.PRICE_CATEGORY as PRICE_CAT2_0_0_,
   pricecatego2_.DESCRIPTION as DESCRIPT3_0_0_,
   productcat3_.ID as ID1_3_1_,
   productcat3_.DESCRIPTION as DESCRIPT2_3_1_,
   productcat3_.PRODUCT_CATEGORY as PRODUCT_3_3_1_,
   pendingrec4_.PENDING_RECORD_NO as REC_REC1_2_2_,
   ---------------------------
  from
      ITEM_RECORDS this_ 
  inner join
      PRICE_CATEGORY pricecatego2_ 
          on this_.PRICE_CATEGORY=pricecatego2_.PRICE_CATEGORY 
  inner join
      PRODUCT_CATEGORY productcat3_ 
          on this_.PRODUCT_CATEGORY=productcat3_.PRODUCT_CATEGORY 
  left outer join
      PENDING_RECORDS pendingrec4_ 
          on this_.PENDING_RECORD_NO=pendingrec4_.PENDING_RECORD_NO 
  where
      this_.PENDING_RECORD_NO=?

在更新记录实体时，应该采取什么措施来防止考虑这些实体进行连接操作？因为这是额外的开销，并且还会生成 ClassCastException。我需要仅在保留或保存期间而不是在更新或删除期间更改关联实体。

我在更新过程中收到以下错误

Servlet.service() for servlet dispatcher threw exception: java.lang.ClassCastException: com.myapps.models.PriceCategory cannot be cast to java.io.Serializable

我应该指定CascadeType吗？或者我应该使用 hibernate CascadeType 而不是我目前用于 PendingRecords 的 JPA？或者还有别的办法吗？请帮我解决这个问题。

提前致谢。

Answer 1

I need associated entites to be changed only during persit or save and not during update or delete

如果在持久化时设置相关实体​​后，它们永远不应该被另一个实体实例覆盖，请使用 @JoinColumn(updatable=false) 。

请注意，由于 Hibernate 的刷新操作顺序，如果相关实体尚不存在，您可能需要先保存它们，刷新 EntityManager ，然后才保存顶级实体。

What should be done to prevent considering these entities for join operations while updating Record entity?

尝试@ManyToOne(fetch=LAZY) 。不过，我并不完全确定这会在合并期间起作用，因为 Hibernate 在合并期间获取相关实体的原因有很多。如果它不起作用，您可能需要编写自定义更新查询。