[castor-dev] Modelling self-referential relationships

Tue, 10 Dec 2002 09:50:12 -0800

I can't seem to get self-referential relationships  to work.  I was wondering if I had a design or modeling problem.
I am trying to model the following.
 
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Description of classes:
UserScenario: can contain a list of WebResources (  UserScenarioWebResource ) , encapsulates a list of Web pages
WebResource: can contain a list of WebResources( WebResourceRelation  ), encapsulates a Web Page.
 
UserScenarioWebResource: extends WebResource, encapsulates a top-level Web Page.
WebResourceRelation: extends WebResource, encapsulates a sub-requests ( images, frames).
------------------------------------------------------------------------------------------------------
Database Schema.
create table user_scenario (
  user_scenario_id       into not null primary key,
  user_scenario_name     varchar(30) not null
);
 
create table web_resource (
  web_resource_id          int not null primary key,
  user_scenario_id         int not null,
  parent_web_resource_id   int,
  name                     varchar(20),
  url                      varchar(100) not null,
  FOREIGN KEY (user_scenario_id) REFERENCES user_scenario(user_scenario_id)
);
 
create table user_scenario_web_resource(
  web_resource_id         int,
  user_scenario_id        int,
  FOREIGN KEY (user_scenario_id) REFERENCES user_scenario(user_scenario_id)
);
create web_resource_relation (
  web_resource_id         int,
  parent_web_resource_id        int
);
-----------------------------------------------------------------------------------------------------------------
 
Mapping file.
<mapping>
 
    <!-- User Scenario -->
    <class name="com.opendemand.jdo.UserScenario" auto-complete="false" identity="userScenarioId" key-generator="MAX">
        <description>Default mapping for class com.opendemand.jdo.UserScenario</description>
        <map-to table="user_scenario"/>
        <field name="userScenarioId" type="integer" >
            <sql name="user_scenario_id" type="integer"/>
        </field>
        <field name="userScenarioName" type="string" >
            <sql name="user_scenario_name" type="char" />
        </field>
        <field name="webResources" type="com.opendemand.jdo.UserScenarioWebResource"
            collection="arraylist"
            get-method="getWebResources" set-method="setWebResources">
            <sql many_key="user_scenario_id"/>
        </field>
    </class>
 
    <!-- Web Resource-->

    <class name="com.opendemand.jdo.WebResource" identity="webResourceId" key-generator="MAX">
        <description>Default mapping for class com.opendemand.jdo.WebResource</description>
        <map-to table="web_resource" />
        <field name="webResourceId" type="integer">
            <sql name="web_resource_id" type="integer" />
        </field>
        <field name="parentWebResource" type="com.opendemand.jdo.WebResource">
            <sql name="parent_web_resource_id" />
        </field>
        <field name="userScenario" type="com.opendemand.jdo.UserScenario">
            <sql name="user_scenario_id" />
        </field>
    </class>
 
   <class name="com.opendemand.jdo.UserScenarioWebResource" identity="webResourceId"
        depends="com.opendemand.jdo.UserScenario" extends="com.opendemand.jdo.UserScenarioWebResource">
        <description>Default mapping for class com.opendemand.jdo.UserScenario</description>
        <map-to table="user_scenario_web_resource"/>
        <field name="webResourceId" type="integer">
            <sql name="web_resource_id" type="integer" />
        </field>
        <field name="userScenario" type="com.opendemand.jdo.UserScenario">
            <sql name="user_scenario_id" />
        </field>
    </class>

   <class name="com.opendemand.jdo.WebResourceRelation" identity="webResourceId"
        depends="com.opendemand.jdo.UserScenario" extends="com.opendemand.jdo.WebResource">
        <description>Default mapping for class com.opendemand.jdo.WebResourceRelation</description>
        <map-to xml="web-resource" table="user_scenario_web_resource"/>
        <field name="webResourceId" type="integer" >
            <sql name="web_resource_id" type="integer" />
        </field>
        <field name="parentWebResource" type="com.opendemand.jdo.WebResource" >
            <sql name="parent_web_resource_id" />
        </field>
    </class>
</map>
 
----------------------------------------------------------------------------------------------------------------
 
I can't seem to get this to work. The user_scenario and the user_scenario_web_resource tables get populated but not the rest of the tables. Any ideas or suggestions on how to model this would be greatly appreciated.
 
 
 
Steve
 
 

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