Class 'Pressbooks\\Book' not found

etienne · January 17, 2018, 6:44pm

Hi,

I’m getting this error thrown in /var/log/apache2/error.log after using the admin panel on a fresh Pressbooks install with a handful of plugins and themes (including the pressbooks-books theme):

PHP Fatal error: Class 'Pressbooks\\Book' not found in /var/www/some/path/wordpress/wp-content/plugins/pressbooks-textbook/inc/admin/class-textbookadmin.php on line 46

Any ideas? Searching the forum doesn’t yield relevant topics.

Thanks,
Etienne

ned · January 17, 2018, 6:45pm

This appears to be a bug with Pressbooks Textbook. FYI @brad.

SteelWagstaff · January 17, 2018, 6:52pm

Etienne–I’m looking at the GitHub version of the file in question: https://github.com/BCcampus/pressbooks-textbook/blob/1838a9cb8dc4afb524afa17ec6f10d78a4445b6c/inc/admin/class-textbookadmin.php#L46. I’m wondering if the issue might not be the double forward slash in the class in your PHP error message? Where’s that coming from?

etienne · January 17, 2018, 7:20pm

I assume the backslash gets escaped in the logs. The code is unchanged on our machine:

if ( \Pressbooks\Book::isBook() ) {

-Etienne

SteelWagstaff · January 17, 2018, 8:04pm

Oh sorry–I meant whatever was calling the class 'Pressbooks\\Book'. To my untrained eye, the PHP error seems to be indicating that something appears to be making a call for that undefined/nonexistent class, and the plugin appears to have a reference to ‘Pressbooks\Book’.

ned · January 17, 2018, 8:06pm

It’s a valid class and method…

github.com

pressbooks/pressbooks/blob/master/inc/class-book.php#L70-L83


	/**
	 * Check if the current blog_id is considered a "book"
	 *
	 * @return bool
	 */
	static function isBook() {


		// Currently, the main site is considered a "blog/landing page" whereas everything else is considered a "book".
		// We might improve this in the future.


		$is_book = ( is_main_site() === false );


		return $is_book;
	}

SteelWagstaff · January 17, 2018, 8:33pm

Yes–sorry for more confusion. My post had two forward slashes in it:
Pressbooks\\Book but it got stripped out. My suspicion was that something in Etienne’s stack was calling Pressbooks\\Book which is an invalid class when it was supposed to be calling Pressbooks\Book which is a valid class.

dac.chartrand · January 17, 2018, 9:22pm

Your autoloader file is missing? See Autoloader for more info: https://docs.pressbooks.org/upgrading/

SteelWagstaff · January 17, 2018, 9:26pm

Thanks, Dac. @etienne, possibly related issue on our Unizin-hosted production instance documented here: SASS Error with Luther. Happy to file a support ticket directly with you if helpful?

dac.chartrand · January 18, 2018, 3:26pm

Because of timestamps, or some cosmic mystery. Pressbooks Textbook is being loaded before Pressbooks.

WordPress Plugins are loaded in random order.

Other plugins that depend on pressbooks (before pressbooks is loaded) should init the autoloader.

The function to do this is in in: https://github.com/pressbooks/pressbooks/blob/dev/compatibility.php

function pb_init_autoloader() {
	static $registered = false;
	if ( ! $registered ) {
		\HM\Autoloader\register_class_path( 'Pressbooks', __DIR__ . '/inc' );
		$registered = true;
	}
}

I believe the issue is the way the compatibility function is coded:

github.com

BCcampus/pressbooks-textbook/blob/dev/pressbooks-textbook.php#L70


/*
|--------------------------------------------------------------------------
| Minimum requirements before either PB or PBT objects are instantiated
|--------------------------------------------------------------------------
|
|
|
|
*/
add_filter(
	'init', function () {
		$min_pb_compatibility_version = '5.0.0';


		if ( ! include_once( WP_PLUGIN_DIR . '/pressbooks/compatibility.php' ) ) {
			add_action(
				'admin_notices', function () {
					echo '<div id="message" class="error fade"><p>' . __( 'PBT cannot find a Pressbooks install.', 'pressbooks-textbook' ) . '</p></div>';
				}
			);


			return;

} elseif ( ! pb_meets_minimum_requirements() ) { /

I don’t think line 75 is ever called? If it were, it would trigger pb_init_autoloader

SteelWagstaff · January 18, 2018, 5:40pm

Hi all, I just heard backchannel from Brad Payne. He’s our for a couple of weeks, but suggested that if we opened up a ticket in github in the pressbooks-textbook repo, his colleague Alex Paredes will be notified and should be able to help us. @etienne, is that something you’d be willing to do?

etienne · January 18, 2018, 5:51pm

Yes, but before we do that we’re going to look at our server configs to make sure the dependencies are right as they should be. More soon!

Etienne