Please Help me in understanding hibernate.

sumittyagi · **Posted:** Mon Nov 20, 2006 3:24 am

I am a very beginner in Hibernate.
I have a scenario.
Please Guide me.

there are three tables questions, answers, and options.

I want to map question class to answer class, and opions class.

The Scenario is: I am mapping question to options, by set element one-to-many collection mapping. option in turn is mapped to answer class by one-to-one mapping. Then question class is again mapped to answer class by one-to-one mapping.

The confusion is: I have read in the documentation, that collection is a value type(not entity type), and can't be associated with more than one entity.
Does that mean I will not be able to form one to one (by using component element) relation between the option and answer, as option is mapped as collection in question.

I am very new to this technology. Please guide me.

The mapping is as follows:

Code:

<hibernate-mapping>
  <class name="Question">
    <id name="qId">
      <generator class="native"/>
    </id>
    <property name="desc" />
    <set name="options" >
      <key column="qid" />
      <one-to-many class="Option" />
    </set>
    <component name="Answer" unique="true">
      <key column="aId" />
      <property name="desc" length="20"/>
      <property name="longdesc" />
    </component>
  </class>

  <class name="Option">
    <id name="qId">
      <generator class="native" />
    </id>
    <component name="Answer" unique="true">
      <key column="aId" />
      <property name="desc" length="20" />
      <property name="longdesc" />
    </component>
  </class>

  <class name="Answer">
    <id name="qId">
     <generator class="native" />
    </id>
      <property name="desc" length="20" />
      <property name="longdesc" />
    </component>
  </class>
<hibernate-mapping>

Please guide me where I am wrong in this mapping, or what are the alternatives I can apply here.

sumittyagi · **Posted:** Mon Nov 20, 2006 8:41 am

I think This will solve my problem:

Please comment on it.

Code:

<hibernate-mapping> 
  <class name="Question"> 
    <id name="questionId" column="question_id">
      <generator class="native"/> 
    </id> 
    <property name="desc" /> 
    <map name="options" table="answer_option">
      <key column="question_id" />
      <index column="option_name" type="string" />
      <many-to-many column="option_id" class="Answer" /> 
    </map> 
    <many-to-one name="answer" class="Answer" column="answer_id" not-null="true" />
  </class> 

  <class name="Answer"> 
    <id name="answerId" column="answer_id"> 
     <generator class="native" /> 
    </id> 
    <property name="desc" length="20" /> 
    <property name="longDesc" column="long_desc" /> 
  </class>
</hibernate-mapping>

Please comment and
Please guide me, if there is any better way.