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Subject: Copying Torque Object
Date: Wed, 24 May 2006 15:12:34 +0200
Message-ID: 
 <F1EF69E69C1EED4FA3BB295B07664EEE523701@srv-master.cadooz-ag.intern>
Thread-Topic: Copying Torque Object
Thread-Index: AcZ/M7hRHNoq0pkVRhiaYjFco81Aig==
From: "Thoralf Rickert" <thoralf.rickert@cadooz.de>
To: "Apache Torque Developers List" <torque-dev@db.apache.org>

Hi!

I've a small problem with the copy() and copyInto() methods in the
generated Torque objects. I've tables with dependencies from other
tables (for example a table "login" which has a foreign key to a table
"address"). I want to use the BaseAddress.copy() method to copy the
address object and save it. If I use this method, it also loads and
copies internally all logins which are linked to the source address to
the new address. So, it makes a deep copy. Is it possible, to override
this behaviour outside the Base* class without creating a totally new
copy() method? I don't think so...

I've noticed this some time a go and wrote my own copy() method in the
extended Address class like this:

public Address copy(boolean deepcopy) throws Exception {
  if (deepcopy)
    return super.copy();
  else {
    Address newAddress =3D new Address();
    newAddress.setFirstname(firstname);
    ....
    return newAddress;
  }
}

But after a little while I've added a new column to the address table
and forgot to update the new copy() method too. So I didn't copy all
data, if I use copy(false) - which takes some time to find and fix. I
can't make a deep copy because there could be many thousands of referer
rows to an address. I just want to copy the address data.

So, the best way would be, that this copy(boolean) method should be
added during BaseAddress generation in that class. I think, it's not
very complicated to add this "feature". Here is my proposal:

1. add in Object.vm a new boolean parameter to copy() like this
    public $table.JavaName copy(boolean deepcopy) throws TorqueException
    {
        return copyInto(new ${table.JavaName}(),deepcopy);
    }
2. create two new downwards compatible methods copy() and copyInto()
    public $table.JavaName copy() throws TorqueException
    {
        return copy(true);
    }
    protected $table.JavaName copyInto($table.JavaName copyObj) throws
TorqueException
    {
        return copyInto(copyObject, true);
    }
3. add a new parameter deepcopy to the old copyInto() method and check
that variable before making the
   deepcopy. I think, it's not necessary to submit that value recursivly
to the referers.
    protected $table.JavaName copyInto($table.JavaName copyObj, boolean)
throws TorqueException
    {
        ....
  #if ($complexObjectModel)
        if (deepcopy) {
    #foreach ($fk in $table.Referrers)
    ...
    #end
        }
  #end
    }

Is that possible or did I forgot something important?

bye
Thoralf


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