作为只读视图的JPA辅助表--Hibernate仍尝试插入行 [英] JPA secondary table as read only view - hibernate still tries to insert rows

问题描述

我有以下实体：

  @Entity 
 @Table（name =ONE） 
 @SecondaryTable（name =VIEW_TWO，pkJoinColumns = @PrimaryKeyJoinColumn（name =ONE_ID））
 public class CpBracket {
 
 @Id 
 private Long id ; 
 
 @Column（name =progress，table =VIEW_TWO，updatable = false，insertable = false）
 private int progress = 0; 
 
（...）
} 
  

正如你所见，该实体使用表 ONE 和（只读）视图 VIEW_TWO 。当我坚持实体时，hibernate正在执行插入视图：

  insert into VIEW_TWO（ONE_ID）values（？）
  

忽略不可更新和不可插入的列进度（即好），它仍然试图插入 ONE_ID 列的值。据我所知，注释@PrimaryKeyJoinColumn将选定列标记为 insertable = false 和 updatable = false 。

如何防止hibernate将行插入到辅助表（视图）中？

解决方案

正如我所知，注释 @PrimaryKeyJoinColumn 将选定的
列标记为insertable = false且updatable = false。

我不认为这可能是这种情况：如果我们如何将记录插入到 @SecondaryTable 中，那么当它是一个实际的表时而不是视图？

既不是 @SecondaryTable 或 @PrimarykeyJoinColumn 有防止插入的方法，那么看起来您的原始解决方案不会起作用，并且需要替代方案。

一种选择是将VIEW_TWO映射为一个 @Entity 并链接到您的课程 CPBracket 作为一个 @OneToOne 关系，级联选项设置为无。

  @Entity 
 @Table（name =VIEW_TWO）
 private CpBracketSummaryData（）{
 
} 
 
 
 @Entity 
 @Table（name =ONE）
 public class CpBracket {
 
 @OneToOne 
 @PrimaryKeyJoinColumn 
 private CPBracketSummaryData summaryData; 
 
 public int getSomeValue（）{
 return summaryData.getSomeValue（）; 
 
 
 
 
 
 
 
第二种选择是使用非JPA兼容，特定于Hibernate的 @Formula 注解。 
 
 
  @Entity 
 @Table（name =ONE）
 public class CpBracket {
 
 @Formula（native sql query）
 private int someValue; 
} 
  
 
 
 
 2016年10月更新
 
 
 <我已经在Hibernate 4.3.10.Final和5.1.0.Final中重新讨论了这一点，并且可以在没有插入的情况下将视图作为 @SecondaryTable ：如果您的映射正确。 
 
 
 场景1   
 
 <加载一个实体进行编辑，不要触及映射到次表的任何字段。没有更新发布到辅助表格
 
 
 
 情景2 
  
 
 
创建并保存一个新的实体并且不设置映射到辅助表的任何字段。没有为辅助表格发布插页
 
 
 
 情景3   
 
 
创建或更新包含映射到辅助表的字段的实体，并且该字段标记为可插入= false且可更新= false。插入 仅用于ID字段的辅助表 - 原始问题中报告的行为。
 
 
 
映射问题原来的问题是辅助表字段是一个基本类型，因此当保存一个新的实体时，Hibernate会认为必须将一个记录写入辅助表的值为零。
  @Column（name =progress，table =VIEW_TWO，updatable = false，insertable = false）
 private int progress = 0; 
  
然后解决方案是用相应的包装类型替换原语并将它们保留为空。然后，当保存一条新记录时，没有任何信息写入辅助表，并且不会插入： 
 
 
  @Column（name =progress，table =VIEW_TWO）
 private整数进度; 
  
 
I've got the following entity:
@Entity
@Table(name = "ONE")
@SecondaryTable(name = "VIEW_TWO", pkJoinColumns = @PrimaryKeyJoinColumn(name="ONE_ID"))
public class CpBracket {

@Id
private Long id;

@Column(name="progress", table="VIEW_TWO", updatable = false, insertable = false)
private int progress = 0;

(...)
}
As you see, this entity uses table ONE and (read only) view VIEW_TWO. When I'm persisting the entity, hibernate is performing insert into view:
insert into VIEW_TWO (ONE_ID) values (?)
It is ignoring the non-updatable and non-insertable column progress (that's good) and it is still trying to insert value of ONE_ID column. As far as I know, the annotation @PrimaryKeyJoinColumn marks selected column as insertable=false and updatable=false.


How can I prevent hibernate from inserting rows into secondary table (view)?
解决方案

  
As far as I know, the annotation @PrimaryKeyJoinColumn marks selected
  column as insertable=false and updatable=false.
I do not believe this can be the case: how then do we get records inserted into the @SecondaryTable when it is an actual table rather than a view?

As neither @SecondaryTable or @PrimarykeyJoinColumn have a means to prevent insert then it would appear that your original solution is not going to work and an alternative is required.

One option is to map VIEW_TWO as an @Entity and link to your class CPBracket as a @OneToOne relationship with cascade options set to none.
@Entity
@Table(name ="VIEW_TWO")
private CpBracketSummaryData(){

}


@Entity
@Table(name = "ONE")
public class CpBracket {

    @OneToOne
    @PrimaryKeyJoinColumn
    private CPBracketSummaryData summaryData;

    public int getSomeValue(){
        return summaryData.getSomeValue();
    }
}
The second option would be to use the non JPA compliant, Hibernate specific @Formula annotation.
@Entity
@Table(name = "ONE")
public class CpBracket {

       @Formula("native sql query")
       private int someValue;
}


Update October 2016

I have revisited this in both Hibernate 4.3.10.Final and 5.1.0.Final and it is possible to have the view as a @SecondaryTable without the insert: if you have the correct mappings.

Scenario 1

Load an entity for edit and do not touch any fields mapped to the secondary table. No update is issued to the secondary table

Scenario 2

Create and save a new entity and do not set any fields mapped to the secondary table. No insert is issued for the secondary table

Scenario 3

Create or update an entity including a field mapped to a secondary table and where this field is marked as insertable = false and updateable = false. An insert is made to the secondary table only for the ID field -the  behaviour reported in the original question.

The issue with the mapping in the original question is the fact that the secondary table field is a primitive type and therefore when saving a new entity Hibernate does think a record has to be written to the secondary table with a value of zero.
@Column(name="progress", table="VIEW_TWO", updatable = false, insertable = false)
private int progress = 0;
The solution then is to replace primitives with the corresponding wrapper types and leave  them as null. Then when saving a new record there is nothing to write to the secondary table and no insert will be made:
@Column(name="progress", table="VIEW_TWO")
private Integer progress;


                        
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