Virtual Pages setup with content database broken in Kirby 5

[mrflix]

Description

I'm upgrading a v4 website to v5 and got greeted by the "Fatal error: Allowed memory size of 1073741824 bytes exhausted" infinite loop error message. Rolling back to the v4 makes the website work again.

The website is using virtual pages from a database. The implementation is based on that guide. Upon further debugging I found out that commenting out this line in the virtual page model fixes error:

public function isDraft(): bool
{
	return in_array($this->content()->status(), ['listed', 'unlisted']) === false;
}

Do you have an idea how this call leads to an infinite loop since v5?

Your setup

Kirby Version
5.1.2

[afbora]

If you could share your complete virtual page class, it might be helpful for us to debug and test it.

[mrflix]

<?php

use Kirby\Uuid\Uuid;

class VoicePage extends Kirby\Cms\Page {
	protected function changeStatusToDraft(): static
	{
		$data['status'] = 'null';

		if ($dbEntry = Db::first('Voices', '*', ['uuid' => $this->uuid()->id()])) {
			return Db::update('Voices', $data, ['uuid' => $this->uuid()->id()]);
		}

		return $this;
	}

	protected function changeStatusToListed(int $position = null): static
	{
		// create a sorting number for the page
		$num = $this->createNum($position);

		// don't sort if not necessary
		if ($this->status() === 'listed' && $num === $this->num()) {
				return $this;
		}
		
		$data['status'] = 'listed';

		if ($dbEntry = Db::first('Voices', '*', ['uuid' => $this->uuid()->id()])) {
				return Db::update('Voices', $data, ['uuid' => $this->uuid()->id()]);
		}

		if ($this->blueprint()->num() === 'default') {
				$this->resortSiblingsAfterListing($num);
		}

		return $this;
	}

	protected function changeStatusToUnlisted(): static
	{
		if ($this->status() === 'unlisted') {
			return $this;
		}

		$data['status'] = 'unlisted';

		if ($dbEntry = Db::first('Voices', '*', ['uuid' => $this->uuid()->id()])) {
			return Db::update('Voices', $data, ['uuid' => $this->uuid()->id()]);
		}

		$this->resortSiblingsAfterUnlisting();

		return $this;
	}

	public function changeTitle(string $title, string $languageCode = null): static
	{
		return $this;
	}

	public function isDraft(): bool
	{
		return in_array($this->content()->status(), ['listed', 'unlisted']) === false;
	}

	public function writeContent(array $data, string $languageCode = null): bool {
		$db_data = [
			'name' => $data['name'],
			'age' => $data['age'],
			'parent_uuid' => $data['parent_uuid'],
			'text' => $data['text'],
			'email' => $data['email'],
			'upvotes' => $data['upvotes'],
			'downvotes' => $data['downvotes'] 
		];

		if ($dbEntry = Db::first('Voices', '*', ['uuid' => $this->uuid()->id()])) {
			return Db::update('Voices', $db_data, ['uuid' => $this->uuid()->id()]);
		} else {
			// erstellen
			$db_data['uuid'] = $this->uuid()->id();
			$db_data['date'] = date('Y-m-d H:i:s');
			$this->slug = new Field($this, 'slug', $this->uuid()->id());
			$db_data['slug'] = $this->uuid()->id();
			try {
				$id = Db::insert('Voices', $db_data);
				return $id;
			} catch(Throwable $e) {
				file_put_contents('php://stderr', $e->getMessage().PHP_EOL);
			}
		}
	}

	public function delete(bool $force = false): bool {
		return Db::delete('Voices', ['uuid' => $this->uuid()->id()]);
	}
}

[afbora]

Tracking the issue

I can reproduce the issue, but not only for virtual pages. If $this->content() is called within the ->isDraft method in any custom page models, it enters an infinite loop.

The infinite loop chain I suspect:

• CustomPage::isDraft() calls $this->content()
• ModelWithContent::content() calls $version->content()
• $version->content() calls $this->storage()->read()
• Storage system (PlainTextStorage) calls ->root() for file reading
• Page::root() calls $this->diruri()
• Page::diruri() calls $this->isDraft()
• So back to step first and infinite loop

Personal note

I'm not sure if this is a bug, regression or a breaking change for 5.0.0.

It might be a stupid guess, but I think the version class might not be caching the content data (or not being able to do it correctly due to a bug) and might be going into an infinite loop because it's re-running the entire model every time.

[bastianallgeier]

@mrflix did you have a look at the database-storage plugin yet? I think it could have some good pointers: https://github.com/getkirby/database-storage/tree/main

[mrflix]

Thanks for the pointer. I didn't look into the database-storage yet. The virtual pages setup worked well so far. I didn't plan on rewriting it using a different approach. I hope the virtual pages setup as described in the guide will continue to work in Kirby 5+.