Assign Yii db model to property in form model?

I have a form model as below…




namespace app\models;


use Yii;

use yii\base\model;

use app\helpers\generalHelper as general;


class SignupForm extends Model {

	

	public $company_name;

	public $first_name;

	public $last_name;

	public $email;

	public $username;

	public $password;

	public $password_again;

	

    /**

     * Validation rules

     * @return array An array of validation rules

     */	

	

	public function rules() {		

        return [

	    //........

        ];

	}


	//..........

	

}



I want to use the Yii DB connection inside a method in this class via the Yii::$app->db reference, but wondering what is the preferred way to set this to a property so that I can access via something like $this->db.

Aren’t all the properties within the class supposed to be reserved for form property names? If not, where is the best place to set it? Should I make a constructor?