Workaround for core bug with preferences limit #88

CHANGELOG.md

@@ -6,6 +6,8 @@ All notable changes to this project will be documented in this file.
 - When a section used to be displayed on a course page and is now displayed as a link,
   the old student preferences about collapsed state affect the visibility of
   the section summary #68
+- Coding error when trying to collapse a large number of sections #88
+  (workaround for the core bug MDL-78073)
 
 ## [4.1.1] - 2024-10-02
 ### Fixed

classes/local/helpers/preferences.php

@@ -0,0 +1,162 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace format_flexsections\local\helpers;
+
+use cache;
+use core_text;
+
+/**
+ * Helps to store and retrieve large user preferences
+ *
+ * @package    format_flexsections
+ * @copyright  Marina Glancy
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+trait preferences {
+
+    /**
+     * Name for the part of the preference
+     *
+     * @param string $name
+     * @param int $cnt
+     * @return string
+     */
+    protected static function get_preference_name(string $name, int $cnt = 0): string {
+        return $cnt ? "{$name}#{$cnt}" : $name;
+    }
+
+    /**
+     * Set a preference for the user (value can be longer than 1333)
+     *
+     * @param string $name
+     * @param string|null $value
+     * @return void
+     */
+    public static function set_long_preference(string $name, ?string $value): void {
+        $allpreferences = array_filter(get_user_preferences(), function($prefname) use ($name) {
+            return $prefname === $name || (strpos($prefname, "{$name}#") === 0);
+        }, ARRAY_FILTER_USE_KEY);
+        $len = ceil(core_text::strlen((string)$value) / 1300);
+        for ($cnt = 0; $cnt < $len; $cnt++) {
+            $pref = self::get_preference_name($name, $cnt);
+            set_user_preference($pref, core_text::substr($value, $cnt * 1300, 1300));
+            unset($allpreferences[$pref]);
+        }
+        foreach (array_keys($allpreferences) as $pref) {
+            unset_user_preference($pref);
+        }
+    }
+
+    /**
+     * Get a preference for the user (value can be longer than 1333)
+     *
+     * @param string $name
+     * @return string
+     */
+    public static function get_long_preference(string $name): string {
+        $allpreferences = array_filter(get_user_preferences(), function($prefname) use ($name) {
+            return $prefname === $name || (strpos($prefname, "{$name}#") === 0);
+        }, ARRAY_FILTER_USE_KEY);
+        $value = '';
+        for ($cnt = 0; $cnt < count($allpreferences); $cnt++) {
+            $value .= $allpreferences[self::get_preference_name($name, $cnt)] ?? '';
+        }
+        return $value;
+    }
+
+    /**
+     * Return the format section preferences.
+     *
+     * @return array of preferences indexed by preference name
+     */
+    public function get_sections_preferences_by_preference(): array {
+        $course = $this->get_course();
+        try {
+            $sectionpreferences = json_decode(
+                self::get_long_preference("coursesectionspreferences_{$course->id}"),
+                true,
+            ) ?: [];
+        } catch (\Throwable $e) {
+            $sectionpreferences = [];
+        }
+        return $sectionpreferences;
+    }
+
+    /**
+     * Return the format section preferences.
+     *
+     * @param string $preferencename preference name
+     * @param int[] $sectionids affected section ids
+     *
+     */
+    public function set_sections_preference(string $preferencename, array $sectionids) {
+        $sectionpreferences = $this->get_sections_preferences_by_preference();
+        $sectionpreferences[$preferencename] = $sectionids;
+        $this->persist_to_user_preference($sectionpreferences);
+    }
+
+    /**
+     * Add section preference ids.
+     *
+     * @param string $preferencename preference name
+     * @param array $sectionids affected section ids
+     */
+    public function add_section_preference_ids(string $preferencename, array $sectionids): void {
+        $sectionpreferences = $this->get_sections_preferences_by_preference();
+        if (!isset($sectionpreferences[$preferencename])) {
+            $sectionpreferences[$preferencename] = [];
+        }
+        foreach ($sectionids as $sectionid) {
+            if (!in_array($sectionid, $sectionpreferences[$preferencename])) {
+                $sectionpreferences[$preferencename][] = $sectionid;
+            }
+        }
+        $this->persist_to_user_preference($sectionpreferences);
+    }
+
+    /**
+     * Remove section preference ids.
+     *
+     * @param string $preferencename preference name
+     * @param array $sectionids affected section ids
+     */
+    public function remove_section_preference_ids(string $preferencename, array $sectionids): void {
+        $sectionpreferences = $this->get_sections_preferences_by_preference();
+        if (!isset($sectionpreferences[$preferencename])) {
+            $sectionpreferences[$preferencename] = [];
+        }
+        foreach ($sectionids as $sectionid) {
+            if (($key = array_search($sectionid, $sectionpreferences[$preferencename])) !== false) {
+                unset($sectionpreferences[$preferencename][$key]);
+            }
+        }
+        $this->persist_to_user_preference($sectionpreferences);
+    }
+
+    /**
+     * Persist the section preferences to the user preferences.
+     *
+     * @param array $sectionpreferences the section preferences
+     */
+    private function persist_to_user_preference(array $sectionpreferences): void {
+        $course = $this->get_course();
+        self::set_long_preference('coursesectionspreferences_' . $course->id, json_encode($sectionpreferences));
+        // Invalidate section preferences cache.
+        $coursesectionscache = cache::make('core', 'coursesectionspreferences');
+        $coursesectionscache->delete($course->id);
+    }
+}

lib.php

@@ -27,6 +27,7 @@
 
 use format_flexsections\constants;
 use core\output\inplace_editable;
+use format_flexsections\local\helpers\preferences;
 
 define('FORMAT_FLEXSECTIONS_COLLAPSED', 1);
 define('FORMAT_FLEXSECTIONS_EXPANDED', 0);
@@ -39,6 +40,7 @@
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 class format_flexsections extends core_courseformat\base {
+    use preferences;
 
     /**
      * Returns true if this course format uses sections.

tests/local/helpers/preferences_test.php

@@ -0,0 +1,189 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace format_flexsections\local\helpers;
+use format_flexsections;
+
+/**
+ * Tests for Flexible sections format
+ *
+ * @covers     \format_flexsections\local\helpers\preferences
+ * @package    format_flexsections
+ * @category   test
+ * @copyright  Marina Glancy
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+final class preferences_test extends \advanced_testcase {
+
+    public function setUp(): void {
+        global $CFG;
+        require_once($CFG->dirroot . '/course/lib.php');
+        parent::setUp();
+    }
+
+    public function test_long_preferences(): void {
+        $this->resetAfterTest();
+        $user = $this->getDataGenerator()->create_user();
+        $this->setUser($user);
+
+        format_flexsections::set_long_preference('name', 'value');
+        $this->assertEquals('value', format_flexsections::get_long_preference('name'));
+        $preferences = get_user_preferences();
+        $this->assertArrayHasKey('name', $preferences);
+        $this->assertArrayNotHasKey('name#1', $preferences);
+
+        $longpref = random_string(2000);
+        format_flexsections::set_long_preference('name', $longpref);
+        $this->assertEquals($longpref, format_flexsections::get_long_preference('name'));
+        $preferences = get_user_preferences();
+        $this->assertArrayHasKey('name', $preferences);
+        $this->assertArrayHasKey('name#1', $preferences);
+        $this->assertArrayNotHasKey('name#2', $preferences);
+
+        $verylongpref = random_string(1300 * 5 + 500);
+        format_flexsections::set_long_preference('name', $verylongpref);
+        $this->assertEquals($verylongpref, format_flexsections::get_long_preference('name'));
+        $preferences = get_user_preferences();
+        $this->assertArrayHasKey('name', $preferences);
+        $this->assertArrayHasKey('name#1', $preferences);
+        $this->assertArrayHasKey('name#2', $preferences);
+        $this->assertArrayHasKey('name#3', $preferences);
+        $this->assertArrayHasKey('name#4', $preferences);
+        $this->assertArrayHasKey('name#5', $preferences);
+        $this->assertArrayNotHasKey('name#6', $preferences);
+
+        format_flexsections::set_long_preference('name', 'value again');
+        $this->assertEquals('value again', format_flexsections::get_long_preference('name'));
+        $preferences = get_user_preferences();
+        $this->assertArrayHasKey('name', $preferences);
+        $this->assertArrayNotHasKey('name#1', $preferences);
+
+        format_flexsections::set_long_preference('name', null);
+        $this->assertEquals('', format_flexsections::get_long_preference('name'));
+        $preferences = get_user_preferences();
+        $this->assertArrayNotHasKey('name', $preferences);
+    }
+
+    /**
+     * Test for the default delete format data behaviour.
+     *
+     * @covers ::set_sections_preference
+     */
+    public function test_set_sections_preference(): void {
+        $this->resetAfterTest();
+        $generator = $this->getDataGenerator();
+        $course = $generator->create_course(['numsections' => 200, 'format' => 'flexsections'],
+            ['createsections' => true]);
+        $user = $generator->create_and_enrol($course, 'student');
+
+        $format = course_get_format($course);
+        $this->setUser($user);
+
+        // Load data from user 1.
+        $format->set_sections_preference('pref1', [1, 2]);
+        $format->set_sections_preference('pref2', [1]);
+        $format->set_sections_preference('pref3', []);
+
+        $preferences = $format->get_sections_preferences();
+        $this->assertEquals(
+            (object)['pref1' => true, 'pref2' => true],
+            $preferences[1]
+        );
+        $this->assertEquals(
+            (object)['pref1' => true],
+            $preferences[2]
+        );
+    }
+
+    public function test_add_section_preference_ids(): void {
+        $this->resetAfterTest();
+        $course = $this->getDataGenerator()->create_course(['numsections' => 200, 'format' => 'flexsections'],
+            ['createsections' => true]);
+        $user = $this->getDataGenerator()->create_and_enrol($course);
+        $this->setUser($user);
+
+        $format = course_get_format($course);
+
+        // Add section preference ids.
+        $format->add_section_preference_ids('pref1', [1, 2]);
+        $format->add_section_preference_ids('pref1', [3]);
+        $format->add_section_preference_ids('pref2', [1]);
+
+        // Get section preferences.
+        $sectionpreferences = $format->get_sections_preferences_by_preference();
+        $this->assertCount(3, $sectionpreferences['pref1']);
+        $this->assertContains(1, $sectionpreferences['pref1']);
+        $this->assertContains(2, $sectionpreferences['pref1']);
+        $this->assertContains(3, $sectionpreferences['pref1']);
+        $this->assertCount(1, $sectionpreferences['pref2']);
+        $this->assertContains(1, $sectionpreferences['pref1']);
+    }
+
+    public function test_add_section_preference_ids_long(): void {
+        $this->resetAfterTest();
+        $course = $this->getDataGenerator()->create_course(['numsections' => 500, 'format' => 'flexsections'],
+            ['createsections' => true]);
+        $user = $this->getDataGenerator()->create_and_enrol($course);
+        $this->setUser($user);
+
+        $format = course_get_format($course);
+
+        // Add section preference ids.
+        $vals = array_keys(array_fill(0, 500, true));
+        $format->add_section_preference_ids('contentcollapsed', $vals);
+
+        // Get section preferences.
+        $sectionpreferences = $format->get_sections_preferences_by_preference();
+        $this->assertCount(500, $sectionpreferences['contentcollapsed']);
+    }
+
+    /**
+     * Test remove_section_preference_ids() method.
+     *
+     * @covers \core_courseformat\base::persist_to_user_preference
+     */
+    public function test_remove_section_preference_ids(): void {
+        $this->resetAfterTest();
+        // Create initial data.
+        $generator = $this->getDataGenerator();
+        $course = $generator->create_course(['numsections' => 200, 'format' => 'flexsections'],
+            ['createsections' => true]);
+        $user = $generator->create_and_enrol($course);
+        // Get the course format.
+        $format = course_get_format($course);
+        // Login as the user.
+        $this->setUser($user);
+        // Set initial preferences.
+        $format->set_sections_preference('pref1', [1, 2, 3]);
+        $format->set_sections_preference('pref2', [1]);
+
+        // Remove section with id = 3 out of the pref1.
+        $format->remove_section_preference_ids('pref1', [3]);
+        // Get section preferences.
+        $sectionpreferences = $format->get_sections_preferences_by_preference();
+        $this->assertCount(2, $sectionpreferences['pref1']);
+        $this->assertCount(1, $sectionpreferences['pref2']);
+
+        // Remove section with id = 2 out of the pref1.
+        $format->remove_section_preference_ids('pref1', [2]);
+        // Remove section with id = 1 out of the pref2.
+        $format->remove_section_preference_ids('pref2', [1]);
+        // Get section preferences.
+        $sectionpreferences = $format->get_sections_preferences_by_preference();
+        $this->assertCount(1, $sectionpreferences['pref1']);
+        $this->assertEmpty($sectionpreferences['pref2']);
+    }
+}