cleanup relationships when deleting questions and lessons, per #263

includes/class.llms.post.relationships.php

@@ -0,0 +1,188 @@
+<?php
+if ( ! defined( 'ABSPATH' ) ) { exit; }
+
+/**
+ * Hooks and actions related to post relationships
+ * @since    [version]
+ * @version  [version]
+ */
+class LLMS_Post_Relationships {
+
+	/**
+	 * Configure relationships
+	 * @var  array
+	 */
+	private $relationships = array(
+
+		'lesson' => array(
+			array(
+				'action' => 'unset',
+				'meta_key' => '_llms_prerequisite',
+				'meta_keys_additional' => array( '_llms_has_prerequisite' ),
+				'post_type' => 'lesson',
+			),
+			array(
+				'action' => 'unset',
+				'meta_key' => '_llms_lesson_id',
+				'post_type' => 'llms_quiz',
+			),
+		),
+
+		'llms_quiz' => array(
+			array(
+				'action' => 'delete', // delete = force delete; trash = move to trash
+				'meta_key' => '_llms_parent_id',
+				'post_type' => 'llms_question',
+			),
+			array(
+				'action' => 'unset',
+				'meta_key' => '_llms_quiz',
+				'meta_keys_additional' => array( '_llms_quiz_enabled' ),
+				'post_type' => 'lesson',
+			),
+		),
+
+	);
+
+	public function __construct() {
+
+		add_action( 'delete_post', array( $this, 'maybe_update_relationships' ) );
+
+	}
+
+	/**
+	 * Delete / Trash posts related to the deleted post
+	 * @param    obj       $post  WP Post that's been deleted
+	 * @param    array     $data  relationship data array
+	 * @return   void
+	 * @since    [version]
+	 * @version  [version]
+	 */
+	private function delete_relationships( $post, $data ) {
+
+		$relationships = $this->get_related_posts( $post->ID, $data['post_type'], $data['meta_key'] );
+
+		$force = ( 'delete' === $data['action'] );
+
+		foreach ( $relationships as $id ) {
+
+			wp_delete_post( $id, $force );
+
+		}
+
+	}
+
+	/**
+	 * Get a list of post types with relationships that should be checked
+	 * @return   array
+	 * @since    [version]
+	 * @version  [version]
+	 */
+	private function get_post_types() {
+		return array_keys( $this->get_relationships() );
+	}
+
+	/**
+	 * Retrieve filtered LifterLMS post relatinoships array
+	 * @return   array
+	 * @since    [version]
+	 * @version  [version]
+	 */
+	private function get_relationships() {
+		return apply_filters( 'llms_get_post_relationships', $this->relationships );
+	}
+
+	/**
+	 * Retrieve an array of post ids related to the deleted post by post type and meta key
+	 * @param    int        $post_id    WP Post ID of the deleted post
+	 * @param    string     $post_type  WP Post type of the related post(s)
+	 * @param    string     $meta_key   meta_key to check for relations by
+	 * @return   array
+	 * @since    [version]
+	 * @version  [version]
+	 */
+	private function get_related_posts( $post_id, $post_type, $meta_key ) {
+
+		global $wpdb;
+		return $wpdb->get_col( $wpdb->prepare(
+			"SELECT p.ID
+			 FROM {$wpdb->posts} AS p
+			 LEFT JOIN {$wpdb->postmeta} AS pm
+			        ON p.ID = pm.post_id
+			       AND pm.meta_key = %s
+			 WHERE p.post_type = %s
+			   AND pm.meta_value = %d",
+			$meta_key,
+			$post_type,
+			$post_id
+		) );
+
+
+	}
+
+	/**
+	 * Check relationships and delete / update related posts when a post is deleted
+	 * Called on `delete_post` hook (before a post is deleted)
+	 * @param    int     $post_id  WP Post ID of the deleted post
+	 * @return   void
+	 * @since    [version]
+	 * @version  [version]
+	 */
+	public function maybe_update_relationships( $post_id ) {
+
+		$post = get_post( $post_id );
+		if ( ! in_array( $post->post_type, $this->get_post_types() ) ) {
+			return;
+		}
+
+		foreach ( $this->get_relationships() as $post_type => $relationships ) {
+
+			foreach ( $relationships as $data ) {
+
+				if ( in_array( $data['action'], array( 'delete', 'trash' ) ) ) {
+
+					$this->delete_relationships( $post, $data );
+
+				} elseif ( 'unset' === $data['action'] ) {
+
+					$this->unset_relationships( $post, $data );
+
+				}
+
+			}
+
+		}
+
+	}
+
+	/**
+	 * Unsets relationship data from post_meta when a post is deleted
+	 * @param    obj       $post  WP Post that's been deleted
+	 * @param    array     $data  relationship data array
+	 * @return   void
+	 * @since    [version]
+	 * @version  [version]
+	 */
+	private function unset_relationships( $post, $data ) {
+
+		$relationships = $this->get_related_posts( $post->ID, $data['post_type'], $data['meta_key'] );
+
+		global $wpdb;
+
+		foreach ( $relationships as $id ) {
+
+			delete_post_meta( $id, $data['meta_key'], $post->ID );
+
+			if ( isset( $data['meta_keys_additional'] ) ) {
+				foreach ( $data['meta_keys_additional'] as $key ) {
+					delete_post_meta( $id, $key );
+				}
+			}
+
+		}
+
+	}
+
+}
+
+return new LLMS_Post_Relationships();

lifterlms.php

@@ -183,7 +183,7 @@ private function define_constants() {
 	/**
 	 * Include required core classes
 	 * @since   1.0.0
-	 * @version 3.16.7
+	 * @version [version]
 	 */
 	private function includes() {
 
@@ -282,6 +282,7 @@ private function includes() {
 		include_once( 'includes/class.llms.lesson.handler.php' );
 		include_once( 'includes/class.llms.course.factory.php' );
 		include_once( 'includes/class.llms.question.types.php' );
+		include_once( 'includes/class.llms.post.relationships.php' );
 		include_once( 'includes/class.llms.review.php' );
 		include_once( 'includes/class.llms.student.dashboard.php' );
 		include_once( 'includes/class.llms.user.permissions.php' );

tests/unit-tests/class.llms.test.post.relationships.php

@@ -0,0 +1,111 @@
+<?php
+/**
+ * Tests for LLMS_Post_Instructors model & functions
+ * @group   post_relationships
+ * @since   [version]
+ * @version [version]
+ */
+class LLMS_Test_Post_Relationships extends LLMS_UnitTestCase {
+
+	/**
+	 * When deleting lessons
+	 * 		A) Any lesson which has this lesson as a prereq should have that prereq removed
+	 * 		   And the has_prereq metavalue should be unset returning "no"
+	 * 		B) Any quiz attached to this lesson should be detached (making it an orphan)
+	 * @return   [type]
+	 * @since    [version]
+	 * @version  [version]
+	 */
+	private function delete_lesson() {
+
+		$courses = $this->generate_mock_courses( 1, 1, 4, 3, 1 );
+		$lessons = llms_get_post( $courses[0] )->get_lessons();
+
+		// add prereqs to all the lessons except the first
+		foreach ( $lessons as $i => $lesson ) {
+
+			if ( 0 === $i ) {
+				continue;
+			}
+
+			$prev = $lessons[ $i - 1 ];
+
+			$lesson->set( 'has_prerequisite', 'yes' );
+			$lesson->set( 'prerequisite', $prev->get( 'id' ) );
+
+		}
+
+		// delete posts and run tests
+		foreach ( $lessons as $i => $lesson ) {
+
+			$quiz = $lesson->get_quiz();
+
+			wp_delete_post( $lesson->get( 'id' ) );
+
+			// quizzes attached to the lesson should now be orphaned
+			if ( $quiz ) {
+				$this->assertTrue( $quiz->is_orphan() );
+			}
+
+			if ( $i === count( $lessons ) - 1 ) {
+				continue;
+			}
+			$next = $lessons[ $i + 1 ];
+
+			// prereqs should be removed
+			$this->assertEquals( 'no', $next->get( 'has_prerequisite' ) );
+			$this->assertEquals( 0, $next->get( 'prerequisite' ) );
+			$this->assertFalse( $next->has_prerequisite() );
+
+		}
+
+	}
+
+	/**
+	 * When a quiz is deleted, all the child questions should be deleted too
+	 * Lesson should switch quiz_enabled to "no"
+	 * @return   void
+	 * @since    [version]
+	 * @version  [version]
+	 */
+	private function delete_quiz() {
+
+		$courses = $this->generate_mock_courses( 1, 1, 1, 1, 20 );
+		$lesson = llms_get_post( llms_get_post( $courses[0] )->get_lessons( 'ids' )[0] );
+		$quiz = $lesson->get_quiz();
+
+		$questions = $quiz->get_questions( 'ids' );
+
+		wp_delete_post( $quiz->get( 'id' ), true );
+
+		foreach ( $questions as $question_id ) {
+
+			$this->assertNull( get_post( $question_id ) );
+
+		}
+
+		$this->assertFalse( $lesson->is_quiz_enabled() );
+
+	}
+
+	/**
+	 * Test all relationships based on post types
+	 * @return   void
+	 * @since    [version]
+	 * @version  [version]
+	 */
+	public function test_maybe_update_relationships() {
+
+		$funcs = array(
+			'delete_quiz',
+			'delete_lesson',
+		);
+		foreach ( $funcs as $func ) {
+
+			call_user_func( array( $this, $func ) );
+
+		}
+
+	}
+
+}