[jboss-user] [EJB 3.0] - EJB QL/ JPQL and search for inheritance
Hello,
I have a problem with creating a QL expression for some of my entities. First of all I
have an entity "Item" which has a ManyToMany reference to 0..* "Tags"
But Tag is just a base class for more complex Entities such as "PlaceMark"
| @Entity
| public class Item implements Serializable{
| private static final long serialVersionUID = -6240744395949853067L;
| .
| .
| .
| /**
| * Get a list of tags associated with the item
| * @return list of tags associated with the item
| */
| @ManyToMany(cascade={CascadeType.PERSIST, CascadeType.MERGE})
| public List<Tag> getTags() {
| return tags;
| }
| public void setTags(List<Tag> tags) {
| this.tags = tags;
| }
| }
|
| @Entity
| @Inheritance(strategy=InheritanceType.SINGLE_TABLE)
| @DiscriminatorColumn(name="dtype",
discriminatorType=DiscriminatorType.STRING)
| @DiscriminatorValue("Tag")
| public class Tag implements Serializable{
| private static final long serialVersionUID = 2432906233376577675L;
|
| long gid;
| String name;
| List<Item> items;
|
| @Id
| @GeneratedValue
| public long getGid() {
| return gid;
| }
| public void setGid(long gid) {
| this.gid = gid;
| }
|
| public String getName() {
| return name;
| }
| public void setName(String value) {
| this.name = value;
| }
|
| @ManyToMany(mappedBy="tags", cascade={CascadeType.PERSIST,
CascadeType.MERGE})
| public List<Item> getItems() {
| return items;
| }
| public void setItems(List<Item> items) {
| this.items = items;
| }
| }
|
| @Entity
| @DiscriminatorValue("PlaceMark")
| public class PlaceMark extends Tag implements Serializable {
| private static final long serialVersionUID = -6646702308712255267L;
|
| boolean visibibilty;
| LookAt lookAt;
| Point point;
|
| public PlaceMark() {
| super.setName("PlaceMark");
| }
|
| @Embedded
| public LookAt getLookAt() {
| return lookAt;
| }
| public void setLookAt(LookAt lookAt) {
| this.lookAt = lookAt;
| }
|
| @Embedded()
| public Point getPoint() {
| return point;
| }
| public void setPoint(Point point) {
| this.point = point;
| }
|
| public boolean isVisibibilty() {
| return visibibilty;
| }
| public void setVisibibilty(boolean visibibilty) {
| this.visibibilty = visibibilty;
| }
|
| public void setName(String value) {
| }
|
| }
|
So now my question, how can I search for items annotaded with different types of tags in
the "Tag" class hierachy?
Thank you in advance.
Regards
---
Joachim
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