ActiveRecord\AbstractRelationship::merge_association_options PHP Method

    protected function merge_association_options($options)
    {
        $available_options = array_merge(self::$valid_association_options, static::$valid_association_options);
        $valid_options = array_intersect_key(array_flip($available_options), $options);
        foreach ($valid_options as $option => $v) {
            $valid_options[$option] = $options[$option];
        }
        return $valid_options;
    }