Yii: Accessing attribute from nested joined table of a model

Question

I have a table "MEDICATION" which is joined with "GENERICS_MED_TRADENAMES" table. "GENERICS_MED_TRADENAMES" table contains drug form of medicine which is referred in LIST_OF_VALUES table. After getting the result set of MEDICATION from DataProvider to show in ListView, I want to access DRUG_FORM description stored in LIST_OF_VALUES table but using Yii Model relations. I tried following but it did not work:

'genMedStrnDrgform' => array(self::BELONGS_TO, 'GenericsMedTradenames', 'gen_med_strn_drgform_id'), -- This is okay, I can access the attributes 
'drugForm' => array(self::BELONGS_TO, 'ListOfValues', 'genMedStrnDrgform.drug_form_id'), -- This does not work since it is nested. Yii thorws error.

To further explain what I want, I have also explained the same in form of SQL queries (Putting a snapshot because indentation is very difficult to present my question in a proper way):

Edit after Pentim10 reply:

I need to display DrugFrom description and tried the following in ListView file but both are not working: drugForm->group_display_val

"$data->genMedStrnDrgform->drugForm->group_display_val"
 "$data->drugForm->group_display_val" 

Answer 1

Place in Medication:

'genMedStrnDrgform' => array(self::BELONGS_TO, 'GenericsMedTradenames', 'gen_med_strn_drgform_id')

Place in GenericsMedTradenames

'drugForm' => array(self::BELONGS_TO, 'ListOfValues', 'drug_form_id')

then do the query like this:

$posts=Medication::model()->findAll(array(
    'with'=>array(
        'genMedStrnDrgform',
        'genMedStrnDrgform.drugForm'
    )
));