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List:       ojb-user
Subject:    RE: Collection creation and sorting
From:       "Gelhar, Wallace Joseph" <GELHARWJ () uwec ! edu>
Date:       2004-04-30 13:29:48
Message-ID: FEBBF51AFF7B8B4B8A2F32F6E63092AEF8425D () COKE ! uwec ! edu
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Hi Tino,

Sure you can do this.  An example:

<class-descriptor class="BuildingImpl" table="tblPlnBuilding" >
...
<collection-descriptor
        name="rooms"
        element-class-ref="RoomImpl">
        <orderby name="roomNo" sort="ASC" />
        <orderby name="roomSuffix" sort="DESC" />
        <inverse-foreignkey field-ref="buildingId"/>
</collection-descriptor>
...
</class-descriptor>

Where roomNo and roomSuffix are attributes on the RoomImpl object.

Wally
-----Original Message-----
From: news [mailto:news@sea.gmane.org] On Behalf Of Tino Schöllhorn
Sent: Friday, April 30, 2004 2:41 AM
To: ojb-user@db.apache.org
Subject: Collection creation and sorting


Hi,

I have a (probably simple) question about sorting collections:

I have 3 classes which I successfully mapped to OJB:

class Company {
   Collection companyTeams;

   public Collection getTeams() {
	//???
   }
}

class CompanyTeam {
   Company c;
   Team t;
   int pos;
}

class Team {
   String name;
   Collection companyTeams;
}

Now I want to achieve the following: The method getTeams() of class 
Company should return all Teams of that Company *sorted by 
CompanyTeam.pos AND Team.name*.

I know that I could write a quite complicated Comparator which just does 
that - but I have many other cases where I had to do that. And writing 
Comparators is not fun and is very error prone.

Is there a way to tell OJB that it should load the Collections in a such 
ordered fashion? I know that one can specify several orderby attributes 
but is it also possible to specify the orderby attributes which are 
located in different tables?

Or should I implement a QueryCustomizer?

In hope for help.
tino



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