public function isValid()

in src/Facebook/InstantArticles/Elements/InstantArticle.php [590:619]


    public function isValid()
    {
        $header_valid = false;
        if ($this->getHeader()) {
            $header_valid = $this->getHeader()->isValid();
        }

        $items = $this->getChildren();
        $one_item_valid = false;
        if ($items) {
            foreach ($items as $item) {
                if ($item->isValid()) {
                    $one_item_valid = true;
                    break;
                }
            }
        }

        $footer_valid = true;
        if ($this->getFooter()) {
            $footer_valid = $this->getFooter()->isValid();
        }

        return
            $this->canonicalURL &&
            !Type::isTextEmpty($this->canonicalURL) &&
            $header_valid &&
            $footer_valid &&
            $one_item_valid;
    }