I just realized that xdoclet can't generate two <key-many-to-one> in <composite-id> , and can't recognize the non-attribute 'column' .

Here is what i've tried:

1. The goal is to generate :
----
<composite-id
name="id"
class="edu.mnscu.housing.vo.RCCampusPK"
>

<key-many-to-one
name="campus"
class="edu.mnscu.housing.vo.Campus"
column="tech_id"
/>
<key-many-to-one
name="campus"
class="edu.mnscu.housing.vo.Campus"
column="rc_id"
/>
....
</composite-id>

------
//xdoclet
/**
*@hibernate.many-to-one class="edu.mnscu.housing.vo.Campus" column="tech_id" not-null="true"
*@hibernate.many-to-one class="edu.mnscu.housing.vo.Campus" column="rc_id" not-null="true"
*/
//file .hbn.xml generated --- missing another <key-many-to-one> for 'rc_id'.
<composite-id
name="id"
class="edu.mnscu.housing.vo.RCCampusPK"
>

<key-many-to-one
name="campus"
class="edu.mnscu.housing.vo.Campus"
column="tech_id"
/>

...
</composite-id>
2. The goal is to generate the following mapping:
---
<composite-id name="id"
class="edu.mnscu.housing.vo.RCCampusPK">
<key-many-to-one name="campus"
class="edu.mnscu.housing.vo.Campus"
<column name="tech_id"/>
<column name="rc_id"/>
</key-many-to-one>
...
</composite-id>
---
//xdoclet
/**
*@hibernate.many-to-one class="edu.mnscu.housing.vo.Campus"
*@hibernate.column="tech_id" not-null="true"
*@hibernate.column="rc_id" not-null="true"
*/
//file generated -- didn't recognize the 'column' , set the default name 'campus' to column.
<composite-id
name="id"
class="edu.mnscu.housing.vo.RCCampusPK"
>

<key-many-to-one
name="campus"
class="edu.mnscu.housing.vo.Campus"
column="campus"
/>
...
</composite-id>

It works for me if just one column in <composite-id> .<many-to-one>. not the case if a nested composite-id (ie. more than one columns ) in <composite-id>.<many-to-one>. Am i missing something?

I would not be using key-many-to-one . Use a normal composite key and then two Many-to-one with update's and insert's set to false on each Many-to-one property.

You know, I've seen the Hibernate team suggest this a few times in the forums, but I've never seen an explanation why. Is there an easy explanation for this? Should key-many-to-one be considered deprecated? (Basically I'm just curious). Thanks.

<key-many-to-one> is generated by xdoclet. The problem occurred if the 'many-to-one' is in 'composite.id' and the 'one' is composite.id also. ie. <composite-id>.<many-to-one>.<composite-id>

Here is :
//one column in composite.id -- works fine.
public class Campus implements Serializable {

private CampusPK _id;
/**
* @hibernate.id generator-class="assigned"
*/
public CampusPK getId() {
return _id;
}
...
}

public class CampusPK implements Serializable {

private String _techId;
private Institution inst;

/**
* @hibernate.property column="tech_id" not-null="true"
*/
public String getTechId () {
return _techId;
}
public void setTechId (String techId ){
_techId= techId;
}
/**
* @hibernate.many-to-one column="rc_id" not-null="true"
*/
public Institution getInst(){
return inst;
}

//mapping generated:
<composite-id
name="id"
class="edu.mnscu.housing.vo.CampusPK"
>
<key-property
name="techId"
type="java.lang.String"
column="tech_id"
/>

<key-many-to-one
name="inst"
class="edu.mnscu.housing.vo.Institution"
column="rc_id"
/>

</composite-id>
...

//now Campus (composite.id) is part of RCCampus (composite.id) primary key - nested composite.id doesn't work , missing second column's mapping.

public class RCCampus implements Serializable {
...
private RCCampusPK _id;
...
/**
* @hibernate.id generator-class="assigned" not-null="true"
*/

public RCCampusPK getId(){
return _id;
}
public void setId( RCCampusPK id ){
_id = id ;
}
...
public class RCCampusPK implements Serializable {
...
private Campus campus;
...

/**
* @hibernate.many-to-one class="edu.mnscu.housing.vo.Campus" column="tech_id" not-null="true"
* hibernate.column="tech_id" not-null="true"
* @hibernate.many-to-one class="edu.mnscu.housing.vo.Campus" column="rc_id" not-null="true"
*/
public Campus getCampus(){
return campus;
}

//mapping generated:
<composite-id
name="id"
class="edu.mnscu.housing.vo.RCCampusPK"
>

<key-many-to-one
name="campus"
class="edu.mnscu.housing.vo.Campus"
column="tech_id"
/>

<key-property
name="FY"
type="java.lang.String"
column="fy"
/>

</composite-id>

Deprecated - well no. But you can map more variations when not using the key-many-to-one option. Use the approach that feels and works best for you.

Chihbn - Dont plavce the many-ton-ones in the key class. Use them in the main class with update=false, insert=false since they are maintained through the key itself.

David - Do you mean no need to have key class? what is the return type for composite-id suppose to be? It'll be nice if you can provide an example. thank you!

Its a composite key so you must have the separate key. The fields of the key will no longer be key-many-to-one and now be simple properties.

The main class will have the many-to-one entries mapped with the update=false, insert=flase.

Where should i put columns mapping? In key class or main class ? Thanks.

I've tried put the key columns mapping in key or main class only and in both key and main class. They don't works for me, similar to key-many-to-one, only one key column got mapped , missing the second column mapping. see the following for map files and errors.

----
//Case1. map 2 key columns( composite-id )in key class only

//main class :
/**
* @hibernate.many-to-one class="edu.mnscu.housing.common.vo.YearTerm" update="false" insert="false"
*/
public YearTerm getYearTerm(){
return yearTerm;
}
//key class:
/**
* @hibernate.property column="yrtr" not-null="true"
*/
public String getYrtr(){
return _yrtr;
}
public void setYrtr( String yrtr ){
_yrtr = yrtr;
}
/**
* @hibernate.property column="rc_id"
*/
public String getRcid(){
return _rcid;
}
//mapping file for main class:
...

<class
name="edu.mnscu.housing.common.vo.AssignmentPeriod"
table="yrtr_cal_dates"
dynamic-update="false"
dynamic-insert="false"
>

<composite-id
name="id"
class="edu.mnscu.housing.common.vo.AssignmentPeriodPK"
>
<key-property
name="yrtr"
type="java.lang.String"
column="yrtr"
/>

<key-property
name="rcid"
type="java.lang.String"
column="rc_id"
/>

....

</composite-id>


<many-to-one
name="yearTerm"
class="edu.mnscu.housing.common.vo.YearTerm"
cascade="none"
outer-join="auto"
update="false"
insert="false"
access="property"
column="yearTerm"
/>


//errors:
Foreign key (yrtr_cal_dates [yearTerm])) must have same number of columns as the referenced primary key (yrtr_cal [yrtr,rc_id])

------------------

//Case2: map 2 columns in both main class and key class, missing second column mapping.
//error: Foreign key (yrtr_cal_dates [yrtr])) must have same number of columns as the referenced p
rimary key (yrtr_cal [yrtr,rc_id])
/**
* @hibernate.many-to-one class="edu.mnscu.housing.common.vo.YearTerm" column="yrtr" update="false" insert="false"
* @hibernate.many-to-one class="edu.mnscu.housing.common.vo.YearTerm" column="rc_id" update="false" insert="false"
**/
public YearTerm getYearTerm(){
return yearTerm;


<hibernate-mapping>
<class
name="edu.mnscu.housing.common.vo.AssignmentPeriod"
table="yrtr_cal_dates"
dynamic-update="false"
dynamic-insert="false"
>

<composite-id
name="id"
class="edu.mnscu.housing.common.vo.AssignmentPeriodPK"
>
<key-property
name="yrtr"
type="java.lang.String"
column="yrtr"
/>

<key-property
name="rcid"
type="java.lang.String"
column="rc_id"
/>

...

</composite-id>


<many-to-one
name="yearTerm"
class="edu.mnscu.housing.common.vo.YearTerm"
cascade="none"
outer-join="auto"
update="false"
insert="false"
access="property"
column="yrtr"
/>
---------------
//Case3: map in main class only, no <key-property> got generated
//see same errors as case2. Foreign key (yrtr_cal_dates [yrtr])) must have
same number of columns as the referenced primary key (yrtr_cal [yrtr,rc_id])

<hibernate-mapping>
<class
name="edu.mnscu.housing.common.vo.AssignmentPeriod"
table="yrtr_cal_dates"
dynamic-update="false"
dynamic-insert="false"
>

<composite-id
name="id"
class="edu.mnscu.housing.common.vo.AssignmentPeriodPK"
>

...
</composite-id>



<many-to-one
name="yearTerm"
class="edu.mnscu.housing.common.vo.YearTerm"
cascade="none"
outer-join="auto"
update="false"
insert="false"
access="property"
column="yrtr"
/>

Since those tables are read only for our apps now, our workaround was to not map associations , map key columns in key class. And do separate query. That works for us.

Try something along the lines of:

Thank you for the info I'll give a try later.