CODEWITHSUNDEEP
javasqlhibernate
user2066880
user2066880

Reputation: 5024

Hibernate 1-to-1 mapping column is not being set

I have 2 tables:

create table EMPLOYEE (
   id INT NOT NULL auto_increment,
   first_name VARCHAR(20) default NULL,
   last_name  VARCHAR(20) default NULL,
   salary     INT  default NULL,
   address    INT NOT NULL,
   PRIMARY KEY (id)
);

create table ADDRESS (
   id INT NOT NULL auto_increment,
   street_name VARCHAR(40) default NULL,
   city_name VARCHAR(40) default NULL,
   state_name VARCHAR(40) default NULL,
   zipcode VARCHAR(10) default NULL,
   PRIMARY KEY (id)
);

where EMPLOYEE.address is a foreign key mapped to ADDRESS

My mapping file is defined as follows:

<hibernate-mapping>
   <class name="Employee" table="EMPLOYEE">
      <meta attribute="class-description">
         This class contains the employee detail. 
      </meta>
      <id name="id" type="int" column="id">
         <generator class="native"/>
      </id>
      <property name="firstName" column="first_name" type="string"/>
      <property name="lastName" column="last_name" type="string"/>
      <property name="salary" column="salary" type="int"/>
      <many-to-one name="address" column="address" unique="true" 
       class="Address" not-null="true"/>
   </class>

   <class name="Address" table="ADDRESS">
      <meta attribute="class-description">
         This class contains the address detail. 
      </meta>
      <id name="id" type="int" column="id">
         <generator class="native"/>
      </id>
      <property name="street" column="street_name" type="string"/>
      <property name="city" column="city_name" type="string"/>
      <property name="state" column="state_name" type="string"/>
      <property name="zipcode" column="zipcode" type="string"/>
   </class>

</hibernate-mapping>

But, when I pull Employee objects all the normal fields are populated normally except the Address field in the Employee plain old object has all the values set to null. What could be causing this?

Upvotes: 1

Views: 64

Answers (1)

talegna
talegna

Reputation: 2403

Unfortunately a bit long for a comment, but hopefully this will give you something to look at:

It is my understanding that NHibernate is actually "lazy by default", this means that the Address object won't be populated until requested, and then (if I remember correctly) only if you are still connected. I've had issues in the past of passing partially loaded objects to a view in my MVC projects and yours sounds similar.

That being said, I've read on several articles that you NHibernate doesn't lazy-load for many-to-one relationships, however I still think this is probably worth looking into. The many-to-one relationship requires the use of a foreign key, and therefore the referencing column must be the primary key. I.e. EMPLOYEE.address = ADDRESS.id.

Once you solve your problem please post what was actually wrong as I am looking to improve my knowledge in NHibernate.

You might find the following articles useful:

And these Questions:

Upvotes: 1

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