Can I do a one-to-one to itself?

crazeinc · **Joined:** Sun Jan 09, 2005 5:16 pm **Posts:** 20

Code:

<hibernate-mapping>
    <class name="org.appfuse.model.Category" table="CATEGORY">
        <id name="id" type="long" column="CATEGORY_ID">
            <generator class="increment"/>
        </id>
      <property name="name" type="string" column="CATEGORY_NAME"/>
      <one-to-one name="parentId" column="CATEGORY_PARENTID" class="org.appfuse.model.Category"/>
    </class>
</hibernate-mapping>

I think it's pretty obvious what I'm trying to do here. Unfortunately, this spits out some errors, so I'm wondering if this is even possible? I just thought I'd save a lookup if I could store the whole parent "object" instead of just an id I'd have to do a lookup on.

anthony · **Posted:** Sun Jan 16, 2005 3:45 pm

many to one is better in your case

crazeinc · **Joined:** Sun Jan 09, 2005 5:16 pm **Posts:** 20

I'm just thinking out loud, but I'm wondering how I would keep track of the hierarchy of the parents if I make it a many-to-one?

crazeinc · **Joined:** Sun Jan 09, 2005 5:16 pm **Posts:** 20

Anybody see anything wrong with this mapping?

Code:

<hibernate-mapping>
    <class name="org.appfuse.model.Category" table="CATEGORY">
        <id name="id" type="long" column="CATEGORY_ID">
            <generator class="increment"/>
        </id>
      <property name="name" type="string" column="CATEGORY_NAME"/>
      <set name="parents" table="CATEGORY_PARENTS">             
         <key column="CATEGORY_ID"/>             
         <many-to-one class="org.appfuse.mode.Category" column="PARENT_ID"/>
      </set> 
    </class>
</hibernate-mapping>

I'm getting this error:

Code:

ERROR - XMLHelper$ErrorLogger.error(48) | Error parsing XML: XML InputStream(14) Attribute "name" is required and must be specified for element type "many-to-one".
ERROR - XMLHelper$ErrorLogger.error(48) | Error parsing XML: XML InputStream(15) The content of element type "set" must match "(meta*,(cache|jcs-cache)?,key,(element|one-to-many|many-to-many|composite-element|many-to-any))".

gavin · **Posted:** Mon Jan 17, 2005 1:05 am

<many-to-one> does not appear inside collection mappings. Do you mean <one-to-many>?

crazeinc · **Joined:** Sun Jan 09, 2005 5:16 pm **Posts:** 20

If I did a one-to-many inside that mapping, would it represent one parent to many categories or vice-versa? I've been working with this associations all night and my brain is fried.

crazeinc · **Joined:** Sun Jan 09, 2005 5:16 pm **Posts:** 20

I'm getting an odd error now:

Code:

ERROR - XMLHelper$ErrorLogger.error(48) | Error parsing XML: XML InputStream(14) Attribute "column" must be declared for element type "one-to-many".
ERROR - ContextLoader.initWebApplicationContext(124) | Context initialization failed

after changing the mapping to a one-to-many relationship

Code:

<hibernate-mapping>
    <class name="org.appfuse.model.Category" table="CATEGORY">
        <id name="id" type="long" column="CATEGORY_ID">
            <generator class="increment"/>
        </id>
      <property name="name" type="string" column="CATEGORY_NAME" not-null="true"/>
      <set name="parents" table="CATEGORY_PARENTS">             
         <key column="CATEGORY_ID"/>             
         <one-to-many class="org.appfuse.mode.Category" column="PARENT_ID"/>
      </set>
    </class>
</hibernate-mapping>

Any ideas?