JPA @EmbeddedId is not generating sequence

Question

I have a table which has composite primary key consisting one sequence and two foreign keys I am able to persist My entity class but it is not generating according to the sequence. The table which has composite primary key consisting one sequence and two foreign keys, hbm2java in maven gives following entities

Here is the Main Entity

package aop.web.teacher.rmodels;

// Generated Dec 14, 2010 8:45:32 PM by Hibernate Tools 3.2.2.GA

import java.util.Date;
import javax.persistence.AttributeOverride;
import javax.persistence.AttributeOverrides;
import javax.persistence.Column;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

/**
 * Schoolmaster generated by hbm2java
 */
@Entity
@Table(name = "schoolmaster", schema = "public")
public class Schoolmaster implements java.io.Serializable {

 private SchoolmasterId id;
        ...


 @EmbeddedId
 @AttributeOverrides({
   @AttributeOverride(name = "id", column = @Column(name = "id", nullable = false)),
   @AttributeOverride(name = "districtId", column = @Column(name = "district_id", nullable = false)),
   @AttributeOverride(name = "typeOfSchool", column = @Column(name = "type_of_school", nullable = false)) })
 public SchoolmasterId getId() {
  return this.id;
 }

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

 @ManyToOne(fetch = FetchType.LAZY)
 @JoinColumn(name = "type_of_school", nullable = false, insertable = false, updatable = false)
 public AopTeachersTypeMaster getAopTeachersTypeMaster() {
  return this.aopTeachersTypeMaster;
 }

 public void setAopTeachersTypeMaster(
   AopTeachersTypeMaster aopTeachersTypeMaster) {
  this.aopTeachersTypeMaster = aopTeachersTypeMaster;
 }

 @ManyToOne(fetch = FetchType.LAZY)
 @JoinColumn(name = "school_nature")
 public AopTeachersSchoolNatureMaster getAopTeachersSchoolNatureMaster() {
  return this.aopTeachersSchoolNatureMaster;
 }

 public void setAopTeachersSchoolNatureMaster(
   AopTeachersSchoolNatureMaster aopTeachersSchoolNatureMaster) {
  this.aopTeachersSchoolNatureMaster = aopTeachersSchoolNatureMaster;
 }

 @ManyToOne(fetch = FetchType.EAGER)
 @JoinColumn(name = "district_id", nullable = false, insertable = false, updatable = false)
 public AopTeachersDistrictMaster getAopTeachersDistrictMaster() {
  return this.aopTeachersDistrictMaster;
 }

 public void setAopTeachersDistrictMaster(
   AopTeachersDistrictMaster aopTeachersDistrictMaster) {
  this.aopTeachersDistrictMaster = aopTeachersDistrictMaster;
 }

 @Column(name = "school_name", length = 50)
 public String getSchoolName() {
  return this.schoolName;
 }

 public void setSchoolName(String schoolName) {
  this.schoolName = schoolName;
 }

 @Column(name = "school_address")
 public String getSchoolAddress() {
  return this.schoolAddress;
 }

 public void setSchoolAddress(String schoolAddress) {
  this.schoolAddress = schoolAddress;
 }

 @Column(name = "school_phone_number", length = 12)
 public String getSchoolPhoneNumber() {
  return this.schoolPhoneNumber;
 }

 public void setSchoolPhoneNumber(String schoolPhoneNumber) {
  this.schoolPhoneNumber = schoolPhoneNumber;
 }

 @Temporal(TemporalType.DATE)
 @Column(name = "establishment_date", length = 13)
 public Date getEstablishmentDate() {
  return this.establishmentDate;
 }

 public void setEstablishmentDate(Date establishmentDate) {
  this.establishmentDate = establishmentDate;
 }

 @Column(name = "school_no_of_teachers")
 public Integer getSchoolNoOfTeachers() {
  return this.schoolNoOfTeachers;
 }

 public void setSchoolNoOfTeachers(Integer schoolNoOfTeachers) {
  this.schoolNoOfTeachers = schoolNoOfTeachers;
 }

 @Column(name = "school_no_of_students")
 public Integer getSchoolNoOfStudents() {
  return this.schoolNoOfStudents;
 }

 public void setSchoolNoOfStudents(Integer schoolNoOfStudents) {
  this.schoolNoOfStudents = schoolNoOfStudents;
 }

}

Here is the embedded PK class.

/**
 * SchoolmasterId generated by hbm2java
 */
@Embeddable
public class SchoolmasterId  implements java.io.Serializable {


     private long id;
     private long districtId;
     private long typeOfSchool;

    public SchoolmasterId() {
    }

    public SchoolmasterId(long id, long districtId, long typeOfSchool) {
       this.id = id;
       this.districtId = districtId;
       this.typeOfSchool = typeOfSchool;
    }


    @Column(name="id", nullable=false)
    @GeneratedValue(strategy=GenerationType.SEQUENCE)
    public long getId() {
        return this.id;
    }

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

    @NaturalId
    @Column(name="district_id", nullable=false)
    public long getDistrictId() {
        return this.districtId;
    }

    public void setDistrictId(long districtId) {
        this.districtId = districtId;
    }
    @NaturalId
    @Column(name="type_of_school", nullable=false)
    public long getTypeOfSchool() {
        return this.typeOfSchool;
    }

    public void setTypeOfSchool(long typeOfSchool) {
        this.typeOfSchool = typeOfSchool;
    }


   public boolean equals(Object other) {
         if ( (this == other ) ) return true;
   if ( (other == null ) ) return false;
   if ( !(other instanceof SchoolmasterId) ) return false;
   SchoolmasterId castOther = ( SchoolmasterId ) other; 

   return (this.getId()==castOther.getId())
 && (this.getDistrictId()==castOther.getDistrictId())
 && (this.getTypeOfSchool()==castOther.getTypeOfSchool());
   }

   public int hashCode() {
         int result = 17;

         result = 37 * result + (int) this.getId();
         result = 37 * result + (int) this.getDistrictId();
         result = 37 * result + (int) this.getTypeOfSchool();
         return result;
   }   


}

Here I am expecting the Id to be autogenerated... I have only added

@NaturalId

and

@GeneratedValue(strategy=GenerationType.SEQUENCE)

I have also tried with GenerationType.AUTO but did not work. Please suggest.

Answer 1

There's one workaround for this issue. I've faced the same condition, have 4 fields as composite keys, out of which 1 need to be generated by sequence. I've not created Embedded class at all, only have 1 @Id field which need to be generated by sequence. Rest all field values will be simple columns, as referential integrity are enforced in DB and also I'm checking values of rest of 3 fields in code to be not null.

In case of error the transaction will rollback.

Answer 2

Just wanna to add my 2c. This works with composite and single primary keys. Prevent for creating sequences, instead, select max + 1 from the table.

Identifiable.java

package my.app.hibernate;

import java.io.Serializable;

public interface Identifiable<T extends Serializable> {
    T getId();
}

CompositeKeyEntity.java

 package my.app.hibernate;

 import java.io.Serializable;

 public interface CompositeKeyEntity<T extends Serializable> extends Identifiable<T> {
 }

SingleKeyEntity.java

package my.app.hibernate;

import java.io.Serializable;

public interface SingleKeyEntity<T extends Serializable> extends Identifiable<T> {
}

AssignedIdentityGenerator.java

package my.app.hibernate;

import java.io.Serializable;
import java.lang.reflect.Field;
import java.util.Arrays;
import java.util.List;

import org.hibernate.Criteria;
import org.hibernate.criterion.Projections;
import org.hibernate.criterion.Restrictions;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.id.IdentityGenerator;
import org.hibernate.internal.CriteriaImpl;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.security.util.FieldUtils;

public class AssignedIdentityGenerator extends IdentityGenerator {
    private static final String ID_FIELD_NAME = "id";
    private final Logger LOG = LoggerFactory.getLogger(this.getClass());
    private Field sequenceField;
    private String entityClassName;

    @Override
    public Serializable generate(SessionImplementor session, Object obj) {
        @SuppressWarnings("unchecked")
        Identifiable<Serializable> identifiable = (Identifiable<Serializable>)obj;

        entityClassName = obj.getClass().getName();
        Criteria criteria = new CriteriaImpl(entityClassName, session);
        criteria.setReadOnly(true);
        Object toSet = null;

        if (identifiable instanceof CompositeKeyEntity) {
            Serializable id = identifiable.getId();
            if (id != null) {
                String embaddebleClassName = id.getClass().getName();
                buildCriteriaForEmbeddedId(id, embaddebleClassName, criteria);
                toSet = id;
            }
        } else if (obj instanceof SingleKeyEntity) {
            toSet = identifiable;
            sequenceField = FieldUtils.getField(identifiable.getClass(), ID_FIELD_NAME);
            buildCriteriaForSingleId(criteria);
        }

        Number one = castToSequenceNumberType(1L);
        Number value = (Number) criteria.uniqueResult();

        if(value != null) {
            value = castToSequenceNumberType(value.longValue() + one.longValue());

            setFieldValue(sequenceField, value, toSet);
        } else {
            value = one;
            setFieldValue(sequenceField, value, toSet);
        }

        return identifiable.getId();
    }

    private void buildCriteriaForSingleId(Criteria criteria) {
        criteria.setProjection(Projections.max(ID_FIELD_NAME).as("seq"));
    }

    private void buildCriteriaForEmbeddedId(Serializable id, String embaddebleClassName, Criteria criteria) {
        List<Field> fields = Arrays.asList(id.getClass().getDeclaredFields());

        class Utils {
            Field field;
            boolean numberFound = false;
        }
        final Utils utils = new Utils();

        for (Field field : fields) {
            if ("serialVersionUID".equals(field.getName()) || "$jacocoData".equals(field.getName())) {
                continue;
            }

            if (Number.class.isAssignableFrom(field.getType())) {
                if (utils.numberFound) {
                    throw new IllegalArgumentException(
                            embaddebleClassName + " has more then one sequence field: " + field.getName() + ", "
                                    + utils.field.getName() + ",...");
                }

                utils.numberFound = true;
                utils.field = field;
                sequenceField = field;

                criteria.setProjection(Projections.max(ID_FIELD_NAME + "." + sequenceField.getName()).as("seq"));
            } else {
                criteria.add(Restrictions.eq(ID_FIELD_NAME + "." + field.getName(), getFieldValue(field, id)));
            }
        }
    }

    private Number castToSequenceNumberType(Number n) {
        return (Number) sequenceField.getType().cast(n);
    }

    private void setFieldValue(Field field, Object value, Object to) {
        try {
            field.setAccessible(true);
            field.set(to, value);
        } catch (IllegalArgumentException | IllegalAccessException e) {
            LOG.error(e.getMessage(), e);
        }
    }

    private Object getFieldValue(Field field, Object from) {
        try {
            field.setAccessible(true);
            return field.get(from);
        } catch (IllegalArgumentException | IllegalAccessException e) {
            LOG.error(e.getMessage(), e);
        }

        return null;
    }
}

Customer.java

package my.app.entities;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import org.hibernate.annotations.GenericGenerator;

import my.app.hibernate.SingleKeyEntity;

@Entity(name = "whatever_entity_name")
@GenericGenerator(name = "WHATEVER_NAMED_GENERATOR", strategy = "my.app.hibernate.AssignedIdentityGenerator")
public class Customer implements SingleKeyEntity<Long> {

    @Id
    @GeneratedValue(generator = "WHATEVER_NAMED_GENERATOR")
    private Long id;
    @Column(nullable = false)
    private String name;
}

CustomerItemsId.java (Item.java ommited as it follows SingleKeyEntity example)

package my.app.entities;

import javax.persistence.Embeddable;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;

@Embeddable
public class CustomerItemsId implements Serializable {
    private static final long serialVersionUID = 1L; //generate one

    @ManyToOne
    @JoinColumn(name = "customer_id")
    private Customer customer;
    @ManyToOne
    @JoinColumn(name = "item_id")
    private Item item;
    private Long seq; //name as you wish
}

CustomerItems.java

package my.app.entities;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import org.hibernate.annotations.GenericGenerator;

import my.app.hibernate.CompositeKeyEntity;

@Entity(name = "whatever_entity_name")
@GenericGenerator(name = "WHATEVER_NAMED_GENERATOR", strategy = "my.app.hibernate.AssignedIdentityGenerator")
public class CustomerItems implements CompositeKeyEntity<CustomerItemsId> {

    @GeneratedValue(generator = "WHATEVER_NAMED_GENERATOR")
    private CustomerItems id;
    @Column(nullable = false)
    private String randomColumn1;
    @Column(nullable = false)
    private String randomColumn2;
}