test.php

protected function onBeforeWrite()
    {
        parent::onBeforeWrite();
        foreach ($this->record as $key => $value) {
            if (preg_match('/Geocontent\[(.+)\]/', $key, $matches)) {
                if (!$value) {
                    $block = $this->GeoContentBlocks()->filter('Code', $matches[1])->first();
                    if ($block && $block->exists()) {
                        $block->delete();
                    }
                } else {
                    $block          = $this->GeoContent($matches[1], true);
                    $block->Content = $value;
                    $block->write();
                }
            }
        }
    }