Amazing association

mpietro · **Joined:** Tue May 16, 2006 7:48 pm **Posts:** 5

Dear Friens, i work with Hibernate for two years,but i never found something that i wasn't capable to fix it.
But this time, i have problemns.
I have the follow legacy model:

Table1: (Search)
PK: searchid.

Table2: (Questions)
PK: searchid, questionNumber(questionnumber is not a sequence, is only a number to identify the question in the Search. The value is always 1, 2 or 3)

Table 3:(Answers)
PK: searchid,questionNumber,answerid

I can´t make an association that works. :(

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

Code:

<class name="Search">
  <id name="SearchID">
    ...
  </id>

  <list name="Questions">
    <key column="SearchID"/>
    <list-index column="questionNumber" base="1"/>
    <one-to-many class="Question"/>
  </list>
</class>

<class name="Question">
  <composite-id name="QuestionID" class="QuestionCompID">
    <key-many-to-one name="Search" column="SearchID"/>
    <key-property name="Number" column="questionNumber"/>
  </composite-id>

  <set name="Answers">
    <key column="AnswerID"/>
    <one-to-many class="Answer"/>
  </set>
</class>

Is this close to what you want?

mpietro · **Joined:** Tue May 16, 2006 7:48 pm **Posts:** 5

Thank you for the reply my friend.
So, i must to have a property type of Search in the class QuestionCompID?
How can i get the Search associated to the Question? throught the property in QuestionCompID?

So i would have something like that: question.getQuestionId().getSearch()
that´s it?

bkmr_77 · **Joined:** Tue Apr 25, 2006 12:04 pm **Posts:** 260

The approach question.getQuestionId().getSearch() will work fine. There is other approach as well.

Code:

<class name="Question"> 
   <composite-id> 
      <key-property name="Search" column="SearchID"/> 
      <key-property name="Number" column="questionNumber"/> 
   </composite-id> 

   <many-to-one name="searchObject" column="SearchID" insert="false" update="false" class="Search"/>

   <set name="Answers"> 
      <key column="AnswerID"/> 
      <one-to-many class="Answer"/> 
   </set> 
</class>

In this case I will have a simple class QuestionPK with two properties( Search, Number ) and have your mapping class Question extend QuestionPK. Hibernate just needs to know your mapping class information i.e. Question and doesnt need to know anything about QuestionPK. Make sure to have QuestionPK implement Serializable interface.

question.getSearch()
question.getSearchObject()

first one gives you only ID information.
second one gives you reference to object.

Check this link also http://www.hibernate.org/117.html#A34

mpietro · **Joined:** Tue May 16, 2006 7:48 pm **Posts:** 5

Hi friend, i understand your point, and i think that is ok for association among search and question.
But the association among question and answer i think that is not another way, we must to use key-many-to-one in the composite-id. Or no?

Regards,

Márcio Di Pietro.

mpietro · **Joined:** Tue May 16, 2006 7:48 pm **Posts:** 5

I resolved the problem. For the relation among Question and Answer i use this:

<set name="answer" inverse="true">
<key>
<column name="questionID"/>
<column name="searchID"/>
</key>
<one-to-many class="Answer"/>
</set>

Thanks.