Define methods associated to a model

[eluser]Trankh1[/eluser]
I’m using Doctrine 1.2 with CodeIgniter v1.7.X

I have a model which extends Doctrine_Record and I want to add custom
methods to this model.

Let’s take e simple example, my model has 2 fields i want to
concatenate. For that i want to create a method like that:

Code:

function concatenate() {
return $this->field1/ $this->field2;
}

Where can i put this in order to call it this way:

Code:

$object->concatenate();

Thanks