Map Hibernate classes with Posit-id and joined-subclass

Question

How can I map a class with Composite-id and extend another class? I’m using the example in: http://www.javacodegeeks.com/2012/08/hibernate-composite-ids-with.html I tried to change the code, but when I try to insert data using this mapping returns the error: Column 'ID' cannot be null

Report java.

public class Report implements Serializable{

    private static final long serialVersionUID = 9146156921169669644L;

    private Integer id;
    private String name;
    private Set<ReportSummary> reportSummaryList  = new HashSet<ReportSummary>();

    public Integer getId() {
         return id;
    }
    public void setId(Integer id) {
         this.id = id;
    }
    public String getName() {
         return name;
    }
    public void setName(String name) {
         this.name = name;
    }
    public Set<ReportSummary> getReportSummaryList() {
         return reportSummaryList;
    }
    public void setReportSummaryList(Set<ReportSummary> reportSummaryList) {
         this.reportSummaryList = reportSummaryList;
    }
}

Report.hbm.xml

<hibernate-mapping>
    <class name="com.example.domain.Report" table="REPORT" >
         <id name="id" type="int" column="id" >
                 <generator class="native"/>
         </id>
         <property name="name">
               <column name="NAME" />
         </property>
         <set name="reportSummaryList" table="REPORT_SUMMARY" cascade="all" inverse="true">
             <key column="RPT_ID" not-null="true"></key>
             <one-to-many class="com.example.domain.ReportSummary"/>
         </set>
     </class>
</hibernate-mapping>

Reportsummary.java

public class ReportSummary implements Serializable {

private static final long serialVersionUID = 8052962961003467437L;

private ReportSummaryId id;
private String name;

public ReportSummaryId getId() {
    return id;
}
public void setId(ReportSummaryId id) {
    this.id = id;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
@Override
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + ((id == null) ? 0 : id.hashCode());
    result = prime * result + ((name == null) ? 0 : name.hashCode());
    return result;
}
@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    ReportSummary other = (ReportSummary) obj;
    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;
  }
}

Reportsummaryid.java

public class ReportSummaryId implements Serializable{

private static final long serialVersionUID = 6911616314813390449L;

private Integer id;
private Report report;

public Integer getId() {
   return id;
}
public void setId(Integer id) {
   this.id = id;
}
public Report getReport() {
   return report;
}
public void setReport(Report report) {
   this.report = report;
}
@Override
public int hashCode() {
   final int prime = 31;
   int result = 1;
   result = prime * result + ((id == null) ? 0 : id.hashCode());
   result = prime * result + ((report == null) ? 0 : report.hashCode());
   return result;
}
@Override
public boolean equals(Object obj) {
   if (this == obj)
      return true;
   if (obj == null)
      return false;
   if (getClass() != obj.getClass())
      return false;
   ReportSummaryId other = (ReportSummaryId) obj;
   if (id == null) {
      if (other.id != null)
         return false;
      } else if (!id.equals(other.id))
         return false;
   if (report == null) {
      if (other.report != null)
         return false;
      } else if (!report.equals(other.report))
         return false;

   return true;
  }
}

Reportsummarydetailed.java

public class ReportSummaryDetailed extends ReportSummary {

private static final long serialVersionUID = -7542202157126903815L;

private String detalhe;


public String getDetalhe() {
    return detalhe;
}
public void setDetalhe(String detalhe) {
    this.detalhe = detalhe;
}
@Override
public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + ((super.getId() == null) ? 0 : super.getId().hashCode());
    result = prime * result + ((super.getName() == null) ? 0 : super.getName().hashCode());
    result = prime * result + ((detalhe == null) ? 0 : detalhe.hashCode());
    return result;
}
@Override
public boolean equals(Object obj) {
    if (this == obj)
        return true;
    if (obj == null)
        return false;
    if (getClass() != obj.getClass())
        return false;
    ReportSummaryDetailed other = (ReportSummaryDetailed) obj;
    if (super.getId() == null) {
       if (other.getId() != null)
          return false;
       } else if (!super.getId().equals(other.getId()))
          return false;
    if (super.getName() == null) {
       if (other.getName() != null)
          return false;
       } else if (!super.getName().equals(other.getName()))
          return false;
    if (detalhe == null) {
        if (other.detalhe != null)
           return false;
        } else if (!detalhe.equals(other.detalhe))
           return false;

   return true;
  }
}

Reportsummary.hbm.xml

<hibernate-mapping>
    <class name="com.example.domain.ReportSummary" table="REPORT_SUMMARY" >
        <composite-id name="id" class="com.example.domain.ReportSummaryId">
             <key-property name="id" column="ID"></key-property>
             <key-many-to-one name="report" 
                              class="com.example.domain.Report"
                              column="RPT_ID"></key-many-to-one>
        </composite-id>
        <property name="name">
             <column name="NAME" />
        </property>

        <joined-subclass name="com.example.domain.ReportSummaryDetailed" extends="ReportSummary" table="REPORT_SUMMARY_DETAILED" >
            <key>
                <column name="ID" />
                <column name="RPT_ID" />
            </key>

            <property name="detalhe">
             <column name="DETALHE" />
        </property>

        </joined-subclass>


    </class>
</hibernate-mapping>

Answer 1

The problem is not that your class is extending another. The problem is that composite-id implies that you know the values beforehand, so the ID field used in Composite-id is not automatically generated. Try to manually do a setId() in his ReportSummaryId to verify this.

I imagine you are working with some legacy system, but for new systems, I would say that you should not use composite Ids, and you should use annotations rather than XML mapping. For high-performance Ids, it is even better to use UUID, especially if the system is distributed. I know these comments do not influence the resolution of your problem, but maybe I can help in the design of a new system ;-)