如何在Hibernate中坚持一个来自非实体子类的实体 [英] How to persist an entity from an non-entity subclass in Hibernate

问题描述

我试图将一个实体扩展成一个用于填充超类字段的非实体。问题是，当我尝试保存它时，Hibernate会抛出一个MappingException。这是因为即使我将ReportParser投影到Report，运行时实例仍然是ReportParser，因此Hibernate抱怨它是未知实体。

  @Entity 
 @Table（name =TB_Reports）
 public class Report 
 {
 Long id; 
字符串名称; 
字符串值; 
 
 @Id 
 @GeneratedValue 
 @Column（name =cReportID）
 public Long getId（）
 {
 return this。 ID; 
} 
 
 public void setId（Long id）
 {
 this.id = id; 
 
 $ b $ @Column（name =cCompanyName）
 public String getname（）
 {
 return this.name; 
} 
 
 public void setName（String name）
 {
 this.name = name; 
 
 $ b $ @Column（name =cCompanyValue）
 public String getValue（）
 {
 return this.name; 
} 
 
 public void setValue（String value）
 {
 this.value = value; 
 
 
 
 
 $ b ReportParser仅用于填写字段。 p> 
 
 
  public class ReportParser extends report 
 {
 public void setName（String htmlstring）
 {
 
} 
 
 public void setValue（String htmlstring）
 {
 ... 
} 
} 
  
尝试将其转换为报表并保存它
  ... 
 ReportParser rp = new ReportParser（）; 
 rp.setName（unparsed_string）; 
 rp.setValue（unparsed_string）; 
报告r =（报告）rp; 
 this.dao.saveReport（r）; 
  
在我转移到ORM之前，我已经使用了这种模式，但我无法弄清楚用Hibernate来做到这一点。是否有可能？
解决方案
实体的子类是否绝对有必要？您可以使用构建器模式：
  public class ReportBuilder {
 private report report; 
 public ReportBuilder（）{
 this.report = new Report（）; 
} 
 public ReportBuilder setName（String unparsedString）{
 //解析
 report.setName（parsedString）; 
返回此; 
} 
 public ReportBuilder setValue（String unparsedString）{
 //解析
 report.setValue（parsedString）; 
返回此; 
} 
 public build（）{
 return report; 
 
 
 
 Report report = new ReportBuilder（）
 .setName（unparsedString）
 .setValue（unparsedString）
 .build ）; 
 dao.saveReport（report）; 
  
 
I am trying to extend an entity into a non-entity which is used to fill the superclass's fields. The problem is that when I try to save it Hibernate throws a MappingException. This is because even though I cast ReportParser to Report, the runtime instance is still a ReportParser so Hibernate complains that it is an unknown entity.
@Entity
@Table(name = "TB_Reports")
public class Report
{
   Long id;
   String name;
   String value;

   @Id
   @GeneratedValue
   @Column(name = "cReportID")
   public Long getId()
   {
      return this.id;
   }

   public void setId(Long id)
   {
      this.id = id;
   }

   @Column(name = "cCompanyName")
   public String getname()
   {
      return this.name;
   }

   public void setName(String name)
   {
      this.name = name;
   }

   @Column(name = "cCompanyValue")
   public String getValue()
   {
      return this.name;
   }

   public void setValue(String value)
   {
      this.value = value;
   }
}
ReportParser is only used to fill in fields.
public class ReportParser extends report
{
   public void setName(String htmlstring)
   {
      ...
   }

   public void setValue(String htmlstring)
   {
      ...
   }
}
Attempt to cast it to a Report and save it
...
ReportParser rp = new ReportParser();
rp.setName(unparsed_string);
rp.setValue(unparsed_string);
Report r = (Report)rp;
this.dao.saveReport(r);
I've used this pattern before I moved to an ORM, but I can't figure out how to do this with Hibernate. Is it possible?
解决方案
Is it absolutely necessary to subclass the entity? You could use the builder pattern:
public class ReportBuilder {
    private Report report;
    public ReportBuilder() {
        this.report = new Report();
    }
    public ReportBuilder setName(String unparsedString) {
        // do the parsing
        report.setName(parsedString);
        return this;
    }
    public ReportBuilder setValue(String unparsedString) {
        // do the parsing
        report.setValue(parsedString);
        return this;
    }
    public Report build() {
        return report;
    }
}

Report report = new ReportBuilder()
                   .setName(unparsedString)
                   .setValue(unparsedString)
                   .build();
dao.saveReport(report);


                        
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