Having an issue with a pretty basic Hibernate 3.6.10 implementation.
I have two classes, schedule and event. The only way to get to an event is through schedule, so I've modeled as a one to many relationship with a schedule having many events.
Here is schedule:
/**
*
*/
package com.heavyweightsoftware.leal.model.schedule;
import java.util.Collection;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import com.heavyweightsoftware.leal.helper.DateHelper;
import com.heavyweightsoftware.leal.model.Pojo;
/**
* A particular collection of events that can be shared
* @author Thom
*/
@Entity
@Table(name = "SCHEDULE")
@NamedQueries( {
@NamedQuery(name = Schedule.COUNT_SCHED_ID, query = "SELECT COUNT(*) " +
"FROM Schedule s " +
"WHERE s.scheduleId = :scheduleId"),
@NamedQuery(name = Schedule.COUNT_SCHED_NAME, query = "SELECT COUNT(*) " +
"FROM ScheduleRole r, Schedule s, SystemUser u " +
"WHERE u.email = :email " +
" AND u.id = r.systemUserId " +
" AND r.scheduleId = s.id " +
" AND s.name = :scheduleName "),
@NamedQuery(name = Schedule.QUERY_EVENTS_BY_USER, query = "SELECT r.roleType, s " +
"FROM Schedule s, ScheduleRole r, SystemUser u " +
"WHERE u.email = :email " +
" AND u.id = r.systemUserId " +
" AND r.scheduleId = s.id " +
" ")
}
)
public class Schedule extends Pojo {
public static final int LENGTH_SCHEDULE_ID = 32;
public static final String COUNT_SCHED_ID = "countScheduleId";
public static final String COUNT_SCHED_NAME = "countScheduleName";
public static final String QUERY_EVENTS_BY_USER = "findEventsByUser";
@Column(name = "ID", nullable=false)
@Id @GeneratedValue(strategy=GenerationType.AUTO)
private Integer id;
@Column(name = "NAME", nullable=false)
private String name;
@Column(name = "SCHEDULE_ID", nullable=false, unique=true, length=LENGTH_SCHEDULE_ID)
private String scheduleId;
@OneToMany(cascade = CascadeType.ALL, fetch=FetchType.EAGER)
private Collection<Event> events;
/* (non-Javadoc)
* @see com.heavyweightsoftware.leal.model.Pojo#toString()
*/
@Override
public String toString() {
StringBuilder sb = new StringBuilder(super.toString());
sb.append('|');
sb.append(getName());
sb.append('|');
sb.append(getScheduleId());
return sb.toString();
}
/* (non-Javadoc)
* @see java.lang.Object#hashCode()
*/
@Override
public int hashCode() {
final int prime = 31;
int result = super.hashCode();
result = prime * result + ((id == null) ? 0 : id.hashCode());
result = prime * result + ((name == null) ? 0 : name.hashCode());
result = prime * result
+ ((scheduleId == null) ? 0 : scheduleId.hashCode());
return result;
}
/* (non-Javadoc)
* @see java.lang.Object#equals(java.lang.Object)
*/
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (!super.equals(obj))
return false;
if (getClass() != obj.getClass())
return false;
Schedule other = (Schedule) 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;
if (scheduleId == null) {
if (other.scheduleId != null)
return false;
} else if (!scheduleId.equals(other.scheduleId))
return false;
return true;
}
/**
* @return the id
*/
public final Integer getId() {
return id;
}
/**
* @param id the id to set
*/
public final void setId(Integer id) {
this.id = id;
}
/**
* @return the name
*/
public final String getName() {
return name;
}
/**
* @param name the name to set
*/
public final void setName(String name) {
this.name = name;
}
/**
* @return
*/
public String getScheduleId() {
return scheduleId == null?scheduleId = DateHelper.getUniqueID():scheduleId;
}
/**
* @param scheduleId
*/
public void setScheduleId(String scheduleId) {
this.scheduleId = scheduleId;
}
/**
* @return the events
*/
public Collection<Event> getEvents() {
return events;
}
/**
* @param events the events to set
*/
public void setEvents(Collection<Event> events) {
this.events = events;
}
}
And here is Event:
/**
*
*/
package com.heavyweightsoftware.leal.model.schedule;
import java.util.Calendar;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.ManyToOne;
import javax.persistence.NamedQueries;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import com.heavyweightsoftware.leal.model.Pojo;
/**
* A particular event entry in a calendar
* @author Thom
*/
@Entity
@Table(name = "EVENT")
@NamedQueries( {
}
)
public class Event extends Pojo {
/**
* Length of the randomly generated event ID
*/
private static final int LENGTH_EVENT_ID = 32;
@Column(name = "ID", nullable=false)
@Id @GeneratedValue(strategy=GenerationType.AUTO)
private Integer id;
@Column(name = "START_TIME")
@Temporal(TemporalType.TIMESTAMP)
private Calendar start;
@Column(name = "END_TIME")
@Temporal(TemporalType.TIMESTAMP)
private Calendar end;
@Column(name = "EVENT_NAME", nullable=false)
private String eventName;
@Column(name = "EVENT_ID", nullable=false, unique=true, length=LENGTH_EVENT_ID)
private String eventId;
@ManyToOne(fetch=FetchType.EAGER)
private Schedule schedule;
@Column(name = "LOCATION")
private String location;
/* (non-Javadoc)
* @see java.lang.Object#hashCode()
*/
@Override
public int hashCode() {
final int prime = 31;
int result = super.hashCode();
result = prime * result + ((end == null) ? 0 : end.hashCode());
result = prime * result
+ ((eventName == null) ? 0 : eventName.hashCode());
result = prime * result + ((id == null) ? 0 : id.hashCode());
result = prime * result
+ ((location == null) ? 0 : location.hashCode());
result = prime * result
+ ((schedule == null) ? 0 : schedule.hashCode());
result = prime * result + ((start == null) ? 0 : start.hashCode());
return result;
}
/* (non-Javadoc)
* @see java.lang.Object#equals(java.lang.Object)
*/
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (!super.equals(obj))
return false;
if (getClass() != obj.getClass())
return false;
Event other = (Event) obj;
if (end == null) {
if (other.end != null)
return false;
} else if (!end.equals(other.end))
return false;
if (eventName == null) {
if (other.eventName != null)
return false;
} else if (!eventName.equals(other.eventName))
return false;
if (id == null) {
if (other.id != null)
return false;
} else if (!id.equals(other.id))
return false;
if (location == null) {
if (other.location != null)
return false;
} else if (!location.equals(other.location))
return false;
if (schedule == null) {
if (other.schedule != null)
return false;
} else if (!schedule.equals(other.schedule))
return false;
if (start == null) {
if (other.start != null)
return false;
} else if (!start.equals(other.start))
return false;
return true;
}
/* (non-Javadoc)
* @see com.heavyweightsoftware.leal.model.Pojo#toString()
*/
@Override
public String toString() {
StringBuilder sb = new StringBuilder(super.toString());
sb.append('|');
sb.append(getEventName());
sb.append('|');
sb.append(getTimestamp(getStart()));
sb.append('-');
sb.append(getTimestamp(getEnd()));
sb.append("|scheduleId=");
sb.append(getSchedule().toString());
sb.append('|');
sb.append(getLocation());
return sb.toString();
}
/**
* @return the id
*/
public final Integer getId() {
return id;
}
/**
* @param id the id to set
*/
public final void setId(Integer id) {
this.id = id;
}
/**
* The start date of the event in UTC
* @return the start
*/
public final Calendar getStart() {
return start;
}
/**
* The start date of the event in UTC
* @param start the start to set
*/
public final void setStart(Calendar start) {
this.start = start;
}
/**
* The end date of the event in UTC
* @return the end
*/
public final Calendar getEnd() {
return end;
}
/**
* The end date of the event in UTC
* @param end the end to set
*/
public final void setEnd(Calendar end) {
this.end = end;
}
/**
* @return the eventId
*/
public String getEventId() {
return eventId;
}
/**
* @param eventId the eventId to set
*/
public void setEventId(String eventId) {
this.eventId = eventId;
}
/**
* @return the eventName
*/
public final String getEventName() {
return eventName;
}
/**
* @param eventName the eventName to set
*/
public final void setEventName(String eventName) {
this.eventName = eventName;
}
/**
* @return the location
*/
public final String getLocation() {
return location;
}
/**
* @param location the location to set
*/
public final void setLocation(String location) {
this.location = location;
}
/**
* @return the schedule
*/
public Schedule getSchedule() {
return schedule;
}
/**
* @param schedule the schedule to set
*/
public void setSchedule(Schedule schedule) {
this.schedule = schedule;
}
}
Everything is working fine except delete. When I implement my DAO through spring and try to delete my schedule, it throws an Integrity Constraint on the Event. It doesn't work if I try to delete the events first either.
getHibernateTemplate.delete(schedule);
How do I do this?
I have reviewed Hibernate Delete Cascade but I do not see how this applies in my situation.
Here is the delete method that I've written:
public void delete(Schedule sched) {
//grab the events
Collection<Event> events = sched.getEvents();
//delete all children
getHibernateTemplate().deleteAll(events);
//flush the buffers
getHibernateTemplate().flush();
//clear the collection
sched.getEvents().clear();
//delete the schedule
super.delete(sched);
}
Thanks.
Best Answer
In short, you're trying to cascade deletions from a parent entity to its children. This a very common problem.
This question offers the answers you seek: Hibernate Delete Cascade
Additionally, consider adding
ON DELETE CASCADEto your database schema to make this behavior explicit in your DBMS.