One to one relationship with hibernation
I am trying to create a one-to-one relationship between two tables.
One of them is Person:
public class Person implements Serializable {
static final long serialVersionUID = 1L;
private long id;
private String _email;
private String _pass;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getEmail() {
return _email;
}
public void set_email(String _email) {
this._email = _email;
}
public String getPass() {
return _pass;
}
public void set_pass(String _pass) {
this._pass = _pass;
}
}
and the second is the ReqC2dmRegId table:
public class ReqC2dmRegId implements Serializable {
private static final long serialVersionUID = 1L;
Person person;
String C2dmid;
private long id;
public ReqC2dmRegId(){}
public String getC2dmid() {
return C2dmid;
}
public void setC2dmid(String c2dmid) {
C2dmid = c2dmid;
}
public ReqC2dmRegId(Person person, String C2dmid) {
super();
this.person = person;
this.C2dmid = C2dmid;
}
public Person getPerson() {
return person;
}
public void setPerson(Person person) {
this.person = person;
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
}
Now, in my program, I always create Person
first, and only when I need to add this one ReqC2dmRegId
.
Now I will try to link these two tables. What I mean is that when I save this one ReqC2dmRegId
(of course I add to the person in the ReqC2dmRegId
correct id) I want mine ReqC2dmRegId
to update or save the newline with the correct Person
id.
These are my hbm files:
ReqC2dmRegId.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated Mar 26, 2012 11:29:57 AM by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping>
<class name="c2dm.ReqC2dmRegId" table="REQC2DMREGID">
<id name="id" type="long">
<generator class="foreign">
<param name="property">person</param>
</generator>
</id>
<one-to-one name="person" class="Entities.Person" cascade="all" />
<property name="C2dmid" type="java.lang.String">
<column name="C2DMID" />
</property>
</class>
</hibernate-mapping>
Person.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated Mar 26, 2012 11:29:57 AM by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping>
<class name="Entities.Person" table="PERSON">
<id name="id" type="long">
<column name="ID" />
<generator class="increment" />
</id>
<property name="_email" type="java.lang.String" access="field">
<column name="_EMAIL" />
</property>
<property name="_pass" type="java.lang.String" access="field">
<column name="_PASS" />
</property>
</class>
</hibernate-mapping>
What am I doing wrong?
When I try to run:
//this should to update or save the object in DB
public void update (Object query){
EntityManager em = emf.createEntityManager();
em.getTransaction().begin();
//em.createNativeQuery(query).executeUpdate();
em.merge(query);
em.flush();
em.getTransaction().commit();
em.close();
}
I get:
attempted to assign id from null one-to-one property:Person
In the end, it should look like this:
Person
**id email _pass**
2 lala@gmail.com 1234
ReqC2dmRegId
**id REQC2DMREGID**
2 ffgghhjj
Update: after giving up, try to figure out how it doesn't work I change my ReqC2dmRegId.hbm.xml to look like this (many-to-one):
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated Mar 27, 2012 9:58:08 PM by Hibernate Tools 3.4.0.CR1 --> <hibernate-mapping>
<class name="c2dm.ReqC2dmRegId" table="REQC2DMREGID">
<id name="id" type="long">
<column name="ID" />
<generator class="identity" />
</id>
<many-to-one name="person" class="Entities.Person" fetch="join" unique="true" cascade="save-update" not-null="true" >
<column name="PERSON" />
</many-to-one>
<property name="C2dmid" type="java.lang.String">
<column name="C2DMID" />
</property>
</class> </hibernate-mapping>
and it works fine, the problem is I am trying to change the ReqC2dmRegId table with my update method it creates now a row with the same personid
id person_id C2dmid
1 3 asd123
2 3 dfvghj
since it doesn't update the correct instated row, creates a new one, and even though I'm making the many-to-one property unique = "true"?
early
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You need to be clear about this relationship: is there one-to-one or many-to-one? It looks like it's a one-way one-way relationship.
Here's an example with annotations:
@Entity
@Table(name="PERSON")
public class Person {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int id;
private String _email;
private String _pass;
//getters and setters
}
And another class:
@Entity
@Table(name="ReqC2dmRegId")
public class ReqC2dmRegId {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int id;
@ManyToOne
@JoinColumn(name = "PERSON_ID")
private Person person;
//getters and setters
}
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