doctrine2/manual/docs/Hierarchical data - Nested set - Setting up.php

<code type="php">
class Menu extends Doctrine_Record { 
    public function setTableDefinition() {

        $this->setTableName('menu');
		
        // add this your table definition to set the table as NestedSet tree implementation
        $this->option('treeImpl', 'NestedSet');
        $this->option('treeOptions', array());        
       
        // you do not need to add any columns specific to the nested set implementation, these are added for you
        $this->hasColumn("name","string",30);

    }
    
    // this __toString() function is used to get the name for the path, see node::getPath()
    public function __toString() {
        return $this->get('name');
    }
}
</code>