Simple koreign key

enaiche · **Posted:** Mon Jan 30, 2006 10:50 am

Hibernate version:3.1
Name and version of the database you are using:POSTGRESQL 8.1
I have 2 tables:
CREATE TABLE h(
id serial NOT NULL,
nume varchar(30),
prenume varchar(20),
CONSTRAINT h_pkey PRIMARY KEY (id)
)

CREATE TABLE honey(
id serial NOT NULL,
name text,
taste text,
id_h int4 NOT NULL,
CONSTRAINT honey_pkey PRIMARY KEY (id),
CONSTRAINT "FK_h" FOREIGN KEY (id_h)
REFERENCES h (id)
ON UPDATE RESTRICT ON DELETE CASCADE
)

and Honey.hbm.xml :
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" >
<hibernate-mapping package="util">
<class name="Honey" table="honey">
<id name="id" column="id" type="java.lang.Integer">
<generator class="sequence">
<param name="sequence">honey_id_seq</param>
</generator>
</id>
<property name="name" column="name" type="java.lang.String" />
<property name="taste" column="taste" type="java.lang.String" />
<many-to-one name="id_h" column="id_h" not-null="true" />
</class>

<class name="H" table="h">
<id name="id" column="id" type="java.lang.Integer">
<generator class="sequence">
<param name="sequence">h_id_seq</param>
</generator>
</id>
<property name="nume" column="nume" type="java.lang.String" />
<property name="prenume" column="prenume" type="java.lang.String" />
</class>
</hibernate-mapping>

and I obtained an error :
org.hibernate.MappingException: An association from the table honey refers to an unmapped class: java.lang.Integer
at org.hibernate.cfg.Configuration.secondPassCompileForeignKeys(Configuration.java:1122)
at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1072)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1156)
at util.HibernateSessionFactory.currentSession(HibernateSessionFactory.java:19)
at util.TestClient.createHoney(TestClient.java:37)
at util.TestClient.main(TestClient.java:19)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:86)
java.lang.NullPointerException
at util.HibernateSessionFactory.currentSession(HibernateSessionFactory.java:25)
at util.TestClient.createHoney(TestClient.java:37)
at util.TestClient.main(TestClient.java:19)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:86)
Exception in thread "main"
Process finished with exit code 1

Why?

rajasaur · **Joined:** Tue Aug 23, 2005 8:52 am **Posts:** 181

Code:

<many-to-one name="id_h" column="id_h" not-null="true" />

should be

Code:

<many-to-one name="id_h" column="id_h" class="H" not-null="true" />

Since you dint mention the class, it looks like it picked it from the Database(int) and thus the java.lang.Integer.

TheXFed · **Posted:** Mon Jan 30, 2006 11:13 am

You should post the code for your Honey class as well. Make sure the many-to-one property of your class is treated as an H class. It seems that you are treating the FK as an Integer in your class, which is why Hibernate is complaining about an unmapped "java.lang.Integer" type. You try something like:

[In Honey.java]

Code:

private H hItem;

public H getH() {
    return hItem;
}

public void setH(H hItem) {
    this.hItem = hItem;
}

[In your Honey.hbm.xml]

Code:

<many-to-one name="h" column="id_h" not-null="true" />

TheXFed · **Posted:** Mon Jan 30, 2006 11:17 am

As far as what rajasaur said, he's not quite right. Here's a quote on the "class" property from the hibernate manual:

Quote:

class (optional - defaults to the property type determined by reflection): The name of the associated class.

So you must've had the FK property stored as an Integer in your Honey class.