Question

I just switched from XML mapping to annotations and had to realize that my serialization class does not work any more!
I hope you can help me to find out the reason 🙂

I have a School class that contains an Address

@Entity
@Table(name="schools")
    public class School {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    @Column(name = "id")
    private Long id;

    @ManyToOne
    @JoinColumn(name="address_id", nullable=true)
    private Address address;
        ...
}

the Address class:

@Entity
@Table(name="addresses")
public class Address {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    @Column(name = "id")
    private Long id;

    @Column(name="street", nullable=false, updatable=true)
    private String street;      // with nr
    ...
}

I try to serialize like this:

sessionFactory = MyFactory.getSessionFactory();
            session = sessionFactory.openSession();

            Transaction tx = session.beginTransaction();

            School mbs = new School("interesting school");
            Address a = new Address("garden street 5","12345", "somewhere");
            mbs.setAddress(a);

            session.save(mbs);
            tx.commit();

This worked before with XML, but now doesn’t..

The first Hibernate query action visible on the console is:
Hibernate: insert into schools (address_id, layout_id, name) values (?, ?, ?)

Therefore an error occurs: ERROR: Column ‘address_id’ cannot be null

How can I fix this?

.

Those are the tables:

CREATE TABLE schools(
    id INTEGER NOT NULL AUTO_INCREMENT,
    name CHAR(50),

    address_id INTEGER NOT NULL,
    layout_id INTEGER NOT NULL,

    CONSTRAINT fk_address FOREIGN KEY (address_id) REFERENCES addresses(id),
    CONSTRAINT fk_layout FOREIGN KEY (layout_id) REFERENCES layout_headers(id),

    PRIMARY KEY (id)
);
CREATE TABLE addresses(
    id INTEGER NOT NULL AUTO_INCREMENT,
    street CHAR(55),
    zip CHAR(6),
    city CHAR(60),

    CONSTRAINT addr_pk PRIMARY KEY (id)
);

In my hibernte.cfg.xml I have the following:

<hibernate-configuration>
    <session-factory>
     ...
        <mapping class="creator.models.school.Address" />
        <mapping class="creator.models.school.Report" />
        <mapping class="creator.models.school.School" />
        <mapping class="creator.models.school.SchoolClass" />
        ...
    </session-factory>
</hibernate-configuration>

Answer 1

You should specify cascade property of @ManyToOne annotation on address field of School class to save address before school. For example, CascadeType.ALL