Deep linking bug in Moodle

[SteelWagstaff]

When users attempt to create deep links in Moodle, they encounter a Invalid or missing lti_message_type parameter. error message. See https://youtu.be/oehV2OyuUQU

This error is triggered by Moodle under these conditions: https://github.com/moodle/moodle/blob/8c5162684144853a8ee3abd0862489e88421ab83/lib/ltiprovider/src/ToolProvider/ToolProvider.php#L680-L682

[SteelWagstaff]

It appears we broke this feature with this commit:

pressbooks-lti-provider/inc/namespace.php

Lines 45 to 52 in 5fea864

	if ( 'lti' === $controller ) {
	if ( \Pressbooks\Book::isBook() || 'createbook' === $action ) {
	// Book
	$admin = Admin::init();
	$controller = new Controller( $admin );
	$params['method'] = $action;
	$controller->handleRequest( 'launch', $params );
	do_exit();

Using https://github.com/pressbooks/pressbooks-lti-provider/blame/a8f8403bd4fd15bdd5d1b02dffa84106cad9fe0b/inc/namespace.php#L45-L51 restores functionality.

[SteelWagstaff]

Deep linking works as expected on integrations: https://youtu.be/DQVPteR8Qao
Book creation works as expected on integrations with the createbook endpoint as well. Nice work @richard015ar !