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mahone9
 Post subject: how to use discriminator right? table per subclass hierarchy
PostPosted: Tue May 12, 2009 7:22 pm 
Newbie

Joined: Wed Jan 21, 2009 4:26 pm
Posts: 12
How to use a discrimator right?

I have a stranger problem with using discriminators.
I was reading that you have to additionaly set the where-clause to the right type (discriminator value).

The problem is here that many-to-one does not provide the where-clause!!!

I was searching on the internet and was reading this article:
http://jroller.com/eyallupu/entry/getti ... en_mapping

Setting Forcing on true did not either help.

Code:
<class="A" abstract="true" table="A">
        <id name="A_ID">  .......  </id>
        <discriminator
           column="Typ"
           type="string"
           length="1"
           not-null="false"
           force="true"           
        />
       
        <property name="name" type="string" />           
               
        <subclass name="SA" extends="A" discriminator-value="S" >
        </subclass>

       <subclass name="LA" extends="A" discriminator-value="L" >
        </subclass>
</class>



Code:
<class name="B" table="B">
          <id name="B_Id"> </id>
          <!-- some stuff here -->

          <idbag name="lcList" table="A_B" cascade="all, delete-orphan" >
           <collection-id type="integer" column="A_B_ID">
            <generator class="identity" />
         </collection-id>
           <key column="B_Id" />           
           <composite-element class="myObj">
              <property name="level" column="level" type="string" length="1" not-null="false" />
              <many-to-one name="la" class="LA" column="A_ID"/>
           </composite-element>           
        </idbag>
</class>


Last edited by mahone9 on Wed May 13, 2009 5:28 am, edited 1 time in total.

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mystic
 Post subject: Re: how to use discriminator right? table per subclass hierarchy
PostPosted: Tue May 12, 2009 8:07 pm 
Regular
Regular

Joined: Tue May 12, 2009 6:08 am
Posts: 92
Here's a working mapping file on a project of mine that works fine:

Code:
    <class name="jobprep.domain.User" table="user_account" abstract="true">
        <id name="id" column="user_account_id" type="long">
            <generator class="sequence">
                <param name="sequence">user_account_id_sequence</param>
            </generator>
        </id>
        <discriminator column="user_type" type="string"/>
        <property name="firstName" column="first_name"/>
        <property name="lastName" column="last_name"/>
        <property name="emailAddress" column="email_address"/>
        <property name="username" column="username"/>
        <property name="password" column="password"/>

        <subclass name="jobprep.domain.Student" discriminator-value="STUDENT">
            <bag name="activeModules" inverse="true" cascade="none" lazy="true">
                <key column="active_module_id" not-null="true"/>
                <one-to-many class="jobprep.domain.ActiveModule"/>
            </bag>
        </subclass>

        <subclass name="jobprep.domain.Teacher" discriminator-value="TEACHER">
            <many-to-one name="educationFacility" class="jobprep.domain.EducationFacility"
                         column="education_facility_id"/>
            <bag name="students" inverse="true" cascade="none" lazy="true">
                <key column="user_account_id" not-null="true"/>
                <one-to-many class="jobprep.domain.Student"/>
            </bag>
        </subclass>

        <subclass name="jobprep.domain.Admin" discriminator-value="ADMIN">
            <bag name="modules" inverse="true" cascade="none" lazy="true">
                <key column="module_id" not-null="true"/>
                <one-to-many class="jobprep.domain.Module"/>
            </bag>
            <bag name="educationFacilities" inverse="true" cascade="none" lazy="true">
                <key column="education_facility_id" not-null="true"/>
                <one-to-many class="jobprep.domain.EducationFacility"/>
            </bag>
        </subclass>
    </class>


I hope that helps.
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mahone9
 Post subject: Re: how to use discriminator right? table per subclass hierarchy
PostPosted: Wed May 13, 2009 5:06 am 
Newbie

Joined: Wed Jan 21, 2009 4:26 pm
Posts: 12
Thanks for your reply.
I guess I try to explain my problem on your mapping file.

Let assume you have 3 tables which are related as n:m relation.

Student 1<-->n StudentSkill n<-->1 Skill

Code:
<class name="AbstractSkill" table="Skill" abstract="true">
        <id name="id" column="Skill_id" type="long">
            <generator class="sequence">
                <param name="sequence">Skill_id_sequence</param>
            </generator>
        </id>
        <discriminator column="skill_type" type="string" not-null="false" force="true"/>
        <property name="name" />
        <property name="description" />

        <subclass name="SoftSkill" discriminator-value="SoftSkill">
            <!--some properties -->
        </subclass>

        <subclass name="HardSkill" discriminator-value="HardSkill">
            <!--some properties -->
        </subclass>
</class>


<class name="jobprep.domain.User" table="user_account" abstract="true">
        <id name="id" column="user_account_id" type="long">
            <generator class="sequence">
                <param name="sequence">user_account_id_sequence</param>
            </generator>
        </id>
        <discriminator column="user_type" type="string"/>
        <property name="firstName" column="first_name"/>
        <property name="lastName" column="last_name"/>
        <property name="emailAddress" column="email_address"/>
        <property name="username" column="username"/>
        <property name="password" column="password"/>

        <subclass name="jobprep.domain.Student" discriminator-value="STUDENT">
            <bag name="activeModules" inverse="true" cascade="none" lazy="true">
                <key column="active_module_id" not-null="true"/>
                <one-to-many class="jobprep.domain.ActiveModule"/>
            </bag>

           [color=#408040]
           <idbag name="softSkills" table="StudentSkill" cascade="all, delete-orphan" >
                 <collection-id type="integer" column="StudentSkill_ID">
                       <generator class="identity" />
                 </collection-id>
                 <key column="user_account_id" />           
                 <composite-element class="StudentSkill">
                        <property name="level" column="level" type="string" length="1" not-null="false" />
                        <many-to-one name="skill" class="SoftSkill" column="Skill_ID"/>
                  </composite-element>           
             </idbag>
            [/color]

           [color=#408040]
           <idbag name="hardSkills" table="StudentSkill" cascade="all, delete-orphan" >
                 <collection-id type="integer" column="StudentSkill_ID">
                       <generator class="identity" />
                 </collection-id>
                 <key column="user_account_id" />           
                 <composite-element class="StudentSkill">
                        <property name="level" column="level" type="string" length="1" not-null="false" />
                        <many-to-one name="skill" class="HardSkill" column="Skill_ID"/>
                  </composite-element>           
             </idbag>
            [/color]


        </subclass>

        <subclass name="jobprep.domain.Teacher" discriminator-value="TEACHER">
            <many-to-one name="educationFacility" class="jobprep.domain.EducationFacility"
                         column="education_facility_id"/>
            <bag name="students" inverse="true" cascade="none" lazy="true">
                <key column="user_account_id" not-null="true"/>
                <one-to-many class="jobprep.domain.Student"/>
            </bag>
        </subclass>

        <subclass name="jobprep.domain.Admin" discriminator-value="ADMIN">
            <bag name="modules" inverse="true" cascade="none" lazy="true">
                <key column="module_id" not-null="true"/>
                <one-to-many class="jobprep.domain.Module"/>
            </bag>
            <bag name="educationFacilities" inverse="true" cascade="none" lazy="true">
                <key column="education_facility_id" not-null="true"/>
                <one-to-many class="jobprep.domain.EducationFacility"/>
            </bag>
        </subclass>
    </class>
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wauwau0977
 Post subject: Re: how to use discriminator right? table per subclass hierarchy
PostPosted: Fri Jun 12, 2009 3:26 am 
Newbie

Joined: Thu Jun 11, 2009 4:32 pm
Posts: 1
hi

i have exactly the same problem as initially posted. as pointed out by the original author of the thread
Code:
<discriminator force="true" ...>
did not resolve the problem.

does anyone has a solution for that? any help would greatly appreciated...

the only workaround i found is adding manually a where clause with the discriminator, which is a bit ugly, but working. e.g.:
Code:
<list name="x" cascade="all" lazy="false"  where="type='DESC_VALUE'" > ... </list>


./patrick heusser
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