休眠外键一对一单向

Question

I have 2 table:

   CREATE TABLE product(
  `id` INT NOT NULL AUTO_INCREMENT,
  // SOME OTHER DATA
  PRIMARY KEY (`id`));


 CREATE TABLE announce (
  `id` INT NOT NULL AUTO_INCREMENT,
  `productId` INT NOT NULL,
  // SOME OTHER DATA
  PRIMARY KEY (`id`),
  UNIQUE INDEX `productIdd_UNIQUE` (`productId` ASC),
  CONSTRAINT `FK_ANNOUNCE_PRODUCT`
    FOREIGN KEY (`productId`)
    REFERENCES `product` (`id`)
    ON DELETE CASCADE
    ON UPDATE CASCADE); 

I would like to realize One-to-One unidirectional on foreign key with hibernate 4

here my configuration hbm.xml :

<hibernate-mapping>
    <class name="mypackage.Announce" table="announce">
        <id name="id" type="int">
            <column name="id" />
            <generator class="native" />
        </id>
        <one-to-one name="product" foreign-key="productId" cascade="all-delete-orphan" lazy="false" />
      ...
    </class>
</hibernate-mapping>



<hibernate-mapping>
    <class name="mypackage.Product" table="product">
        <id name="id" type="int">
            <column name="id" />
            <generator class="native" />
        </id>
        ...
    </class>
</hibernate-mapping>

I'm able to get the data in base, but when i tried to create an announce with an existing product my code throw an SQLException

22:56:17.565 DEBUG ohejdbc.spi.SqlExceptionHelper - could not execute statement [n/a] java.sql.SQLException: Field 'productId' doesn't have a default value

The save generate the id of my foreign key, but i don't understand why.

the java code (my dao make base instruction like sessionFactory.save etc...):

Announce announce = new Announce();
...
Product product = this.productDao.getProduct(productId);
announce.setProduct(product);

this.announceDao.save(announce);

Someone have an idea how to solve my problem ?

Answer 1

Your current configuration tells hibernate to use the primary key as association between both tables, where you want to use a separate column (at least that is what you ddl allows).

A one-to-one mapping in xml should be defined with a <many-to-one unique="true" column=".."/> . This is very confusing, I agree.

<hibernate-mapping>
  <class name="mypackage.Announce" table="announce">
  ...
    <many-to-one name="product" columm="productId" cascade="all-delete-orphan" lazy="false" unique="true"/>
 ... 
  </class>
</hibernate-mapping>