How to build relations to Multiple IDs separated by comma in Yii

I was creating a form. Certian fields of the form uses checkbox and may return multiple choices and I have to store all of those IDs to a single field separated by a comma or semicolon.

Now what I am looking to is how can I build a relation to that record in Yii Framework. Usually we use

'groupName' => array(self::BELONGS_TO, 'Lookup', 'group'),
'p_cpu' => array(self::BELONG开发者_JAVA技巧S_TO, 'Product', 'cpu'),

But how will I do it in the following manner

'p_additionalSoftwares' => array(self::BELONGS_TO, 'Product', 'additionalSoftwares'),

When the additionalSoftwares contain something like 2,8

As this is not a real BELONGS_TO relation with a foreign key you can not use Yii's built in functions. You may write a custom relation for this case based on CBaseActiveRelation or CActiveRelation, but I have no experience in that, but this may be the cleanest solution.

Another option would be to overwrite the get handler for your attribute, like*

public function getP_additionalSoftwares(){
  //Use value from database in attributes and split into array with primary keys
  $pks = explode(",",$this->attributes['p_additionalSoftwares']);
  //Query database
  $models = $this->findByPks($pks);
  return $models;
}

In your view:

$model->p_additionalSoftwares

Should return an array of models, like a relation.

Note: This may impact performance, because you may get a large number of subrequests to the database, as the records are all lazy loaded.

**code untested*