Yii2: How to get extraFields from associated data model?

Question

Yii

There are two AR models: A,B. Model B connects to model A via hasOne (iata field):

 public function getIata()
    {
        return $this->hasOne(B::className(),
                        ['iata_id' => 'iata_id']);
    }

Model B has an extraField f:

    public function extraFields()
    {
        return ['f' => function(){ return "Something"; }];
    }

I need, when selecting an instance of model "A", to get the associated model "B" with the field "F".
Option

$a = A::findOne(1)->toArray([], ['iata', 'f', 'iata.f', 'F'], true);

Does not help. The iata field returns the associated model B without the additional field.
How to be?

Answer 1

read here https://github.com/yiisoft/yii2/blob/master/docs/g... assignment of extraFields - an indication of which relations to return to the Rest controller
And you will have to write the conversion to an array yourself