atk4\data\Join::addField PHP Method

addField() public method

Adding field into join will automatically associate that field with this join. That means it won't be loaded from $table, but form the join instead.
public addField ( $n, $defaults = [] )
    public function addField($n, $defaults = [])
    {
        $defaults['join'] = $this;
        return $this->owner->addField($this->prefix . $n, $defaults);
    }