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See Release Notes
Long Term Support Release

  • Bug fixes for general core bugs in 4.1.x will end 13 November 2023 (12 months).
  • Bug fixes for security issues in 4.1.x will end 10 November 2025 (36 months).
  • PHP version: minimum PHP 7.4.0 Note: minimum PHP version has increased since Moodle 4.0. PHP 8.0.x is supported too.
<?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/>.

/**
 * Base class for conditional availability information (for module or section).
 *
 * @package core_availability
 * @copyright 2014 The Open University
 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

namespace core_availability;

defined('MOODLE_INTERNAL') || die();

/**
 * Base class for conditional availability information (for module or section).
 *
 * @package core_availability
 * @copyright 2014 The Open University
 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
abstract class info {
    /** @var \stdClass Course */
    protected $course;

    /** @var \course_modinfo Modinfo (available only during some functions) */
    protected $modinfo = null;

    /** @var bool Visibility flag (eye icon) */
    protected $visible;

    /** @var string Availability data as JSON string */
    protected $availability;

    /** @var tree Availability configuration, decoded from JSON; null if unset */
    protected $availabilitytree;

    /** @var array|null Array of information about current restore if any */
    protected static $restoreinfo = null;

    /**
     * Constructs with item details.
     *
     * @param \stdClass $course Course object
     * @param int $visible Value of visible flag (eye icon)
     * @param string $availability Availability definition (JSON format) or null
     * @throws \coding_exception If data is not valid JSON format
     */
    public function __construct($course, $visible, $availability) {
        // Set basic values.
        $this->course = $course;
        $this->visible = (bool)$visible;
        $this->availability = $availability;
    }

    /**
     * Obtains the course associated with this availability information.
     *
     * @return \stdClass Moodle course object
     */
    public function get_course() {
        return $this->course;
    }

    /**
     * Gets context used for checking capabilities for this item.
     *
     * @return \context Context for this item
     */
    public abstract function get_context();

    /**
     * Obtains the modinfo associated with this availability information.
     *
     * Note: This field is available ONLY for use by conditions when calculating
     * availability or information.
     *
     * @return \course_modinfo Modinfo
     * @throws \coding_exception If called at incorrect times
     */
    public function get_modinfo() {
        if (!$this->modinfo) {
            throw new \coding_exception(
                    'info::get_modinfo available only during condition checking');
        }
        return $this->modinfo;
    }

    /**
     * Gets the availability tree, decoding it if not already done.
     *
     * @return tree Availability tree
     */
    public function get_availability_tree() {
        if (is_null($this->availabilitytree)) {
            if (is_null($this->availability)) {
                throw new \coding_exception(
                        'Cannot call get_availability_tree with null availability');
            }
            $this->availabilitytree = $this->decode_availability($this->availability, true);
        }
        return $this->availabilitytree;
    }

    /**
     * Decodes availability data from JSON format.
     *
     * This function also validates the retrieved data as follows:
     * 1. Data that does not meet the API-defined structure causes a
     *    coding_exception (this should be impossible unless there is
     *    a system bug or somebody manually hacks the database).
     * 2. Data that meets the structure but cannot be implemented (e.g.
     *    reference to missing plugin or to module that doesn't exist) is
     *    either silently discarded (if $lax is true) or causes a
     *    coding_exception (if $lax is false).
     *
     * @param string $availability Availability string in JSON format
     * @param boolean $lax If true, throw exceptions only for invalid structure
     * @return tree Availability tree
     * @throws \coding_exception If data is not valid JSON format
     */
    protected function decode_availability($availability, $lax) {
        // Decode JSON data.
        $structure = json_decode($availability);
        if (is_null($structure)) {
            throw new \coding_exception('Invalid availability text', $availability);
        }

        // Recursively decode tree.
        return new tree($structure, $lax);
    }

    /**
     * Determines whether this particular item is currently available
     * according to the availability criteria.
     *
     * - This does not include the 'visible' setting (i.e. this might return
     *   true even if visible is false); visible is handled independently.
     * - This does not take account of the viewhiddenactivities capability.
     *   That should apply later.
     *
     * Depending on options selected, a description of the restrictions which
     * mean the student can't view it (in HTML format) may be stored in
     * $information. If there is nothing in $information and this function
     * returns false, then the activity should not be displayed at all.
     *
     * This function displays debugging() messages if the availability
     * information is invalid.
     *
     * @param string $information String describing restrictions in HTML format
     * @param bool $grabthelot Performance hint: if true, caches information
     *   required for all course-modules, to make the front page and similar
     *   pages work more quickly (works only for current user)
     * @param int $userid If set, specifies a different user ID to check availability for
     * @param \course_modinfo $modinfo Usually leave as null for default. Specify when
     *   calling recursively from inside get_fast_modinfo()
     * @return bool True if this item is available to the user, false otherwise
     */
    public function is_available(&$information, $grabthelot = false, $userid = 0,
            \course_modinfo $modinfo = null) {
        global $USER;

        // Default to no information.
        $information = '';

        // Do nothing if there are no availability restrictions.
        if (is_null($this->availability)) {
            return true;
        }

        // Resolve optional parameters.
        if (!$userid) {
            $userid = $USER->id;
        }
        if (!$modinfo) {
            $modinfo = get_fast_modinfo($this->course, $userid);
        }
        $this->modinfo = $modinfo;

        // Get availability from tree.
        try {
            $tree = $this->get_availability_tree();
            $result = $tree->check_available(false, $this, $grabthelot, $userid);
        } catch (\coding_exception $e) {
            $this->warn_about_invalid_availability($e);
            $this->modinfo = null;
            return false;
        }

        // See if there are any messages.
        if ($result->is_available()) {
            $this->modinfo = null;
            return true;
        } else {
            // If the item is marked as 'not visible' then we don't change the available
            // flag (visible/available are treated distinctly), but we remove any
            // availability info. If the item is hidden with the eye icon, it doesn't
            // make sense to show 'Available from <date>' or similar, because even
            // when that date arrives it will still not be available unless somebody
            // toggles the eye icon.
            if ($this->visible) {
                $information = $tree->get_result_information($this, $result);
            }

            $this->modinfo = null;
            return false;
        }
    }

    /**
     * Checks whether this activity is going to be available for all users.
     *
     * Normally, if there are any conditions, then it may be hidden depending
     * on the user. However in the case of date conditions there are some
     * conditions which will definitely not result in it being hidden for
     * anyone.
     *
     * @return bool True if activity is available for all
     */
    public function is_available_for_all() {
< if (is_null($this->availability)) {
> global $CFG; > if (is_null($this->availability) || empty($CFG->enableavailability)) {
return true; } else { try { return $this->get_availability_tree()->is_available_for_all(); } catch (\coding_exception $e) { $this->warn_about_invalid_availability($e); return false; } } } /** * Obtains a string describing all availability restrictions (even if * they do not apply any more). Used to display information for staff * editing the website. * * The modinfo parameter must be specified when it is called from inside * get_fast_modinfo, to avoid infinite recursion. * * This function displays debugging() messages if the availability * information is invalid. * * @param \course_modinfo $modinfo Usually leave as null for default * @return string Information string (for admin) about all restrictions on * this item */ public function get_full_information(\course_modinfo $modinfo = null) { // Do nothing if there are no availability restrictions. if (is_null($this->availability)) { return ''; } // Resolve optional parameter. if (!$modinfo) { $modinfo = get_fast_modinfo($this->course); } $this->modinfo = $modinfo; try { $result = $this->get_availability_tree()->get_full_information($this); $this->modinfo = null; return $result; } catch (\coding_exception $e) { $this->warn_about_invalid_availability($e); return false; } } /** * In some places we catch coding_exception because if a bug happens, it * would be fatal for the course page GUI; instead we just show a developer * debug message. * * @param \coding_exception $e Exception that occurred */ protected function warn_about_invalid_availability(\coding_exception $e) { $name = $this->get_thing_name(); $htmlname = $this->format_info($name, $this->course); // Because we call format_info here, likely in the middle of building dynamic data for the // activity, there could be a chance that the name might not be available. if ($htmlname === '') { // So instead use the numbers (cmid) from the tag. $htmlname = preg_replace('~[^0-9]~', '', $name); } $info = 'Error processing availability data for &lsquo;' . $htmlname . '&rsquo;: ' . s($e->a); debugging($info, DEBUG_DEVELOPER); } /** * Called during restore (near end of restore). Updates any necessary ids * and writes the updated tree to the database. May output warnings if * necessary (e.g. if a course-module cannot be found after restore). * * @param string $restoreid Restore identifier * @param int $courseid Target course id * @param \base_logger $logger Logger for any warnings * @param int $dateoffset Date offset to be added to any dates (0 = none) * @param \base_task $task Restore task */ public function update_after_restore($restoreid, $courseid, \base_logger $logger, $dateoffset, \base_task $task) { $tree = $this->get_availability_tree(); // Set static data for use by get_restore_date_offset function. self::$restoreinfo = array('restoreid' => $restoreid, 'dateoffset' => $dateoffset, 'task' => $task); $changed = $tree->update_after_restore($restoreid, $courseid, $logger, $this->get_thing_name()); if ($changed) { // Save modified data. if ($tree->is_empty()) { // If the tree is empty, but the tree has changed, remove this condition. $this->set_in_database(null); } else { $structure = $tree->save(); $this->set_in_database(json_encode($structure)); } } } /** * Gets the date offset (amount by which any date values should be * adjusted) for the current restore. * * @param string $restoreid Restore identifier * @return int Date offset (0 if none) * @throws coding_exception If not in a restore (or not in that restore) */ public static function get_restore_date_offset($restoreid) { if (!self::$restoreinfo) { throw new coding_exception('Only valid during restore'); } if (self::$restoreinfo['restoreid'] !== $restoreid) { throw new coding_exception('Data not available for that restore id'); } return self::$restoreinfo['dateoffset']; } /** * Gets the restore task (specifically, the task that calls the * update_after_restore method) for the current restore. * * @param string $restoreid Restore identifier * @return \base_task Restore task * @throws coding_exception If not in a restore (or not in that restore) */ public static function get_restore_task($restoreid) { if (!self::$restoreinfo) { throw new coding_exception('Only valid during restore'); } if (self::$restoreinfo['restoreid'] !== $restoreid) { throw new coding_exception('Data not available for that restore id'); } return self::$restoreinfo['task']; } /** * Obtains the name of the item (cm_info or section_info, at present) that * this is controlling availability of. Name should be formatted ready * for on-screen display. * * @return string Name of item */ protected abstract function get_thing_name(); /** * Stores an updated availability tree JSON structure into the relevant * database table. * * @param string $availabilty New JSON value */ protected abstract function set_in_database($availabilty); /** * In rare cases the system may want to change all references to one ID * (e.g. one course-module ID) to another one, within a course. This * function does that for the conditional availability data for all * modules and sections on the course. * * @param int|\stdClass $courseorid Course id or object * @param string $table Table name e.g. 'course_modules' * @param int $oldid Previous ID * @param int $newid New ID * @return bool True if anything changed, otherwise false */ public static function update_dependency_id_across_course( $courseorid, $table, $oldid, $newid) { global $DB; $transaction = $DB->start_delegated_transaction(); $modinfo = get_fast_modinfo($courseorid); $anychanged = false; foreach ($modinfo->get_cms() as $cm) { $info = new info_module($cm); $changed = $info->update_dependency_id($table, $oldid, $newid); $anychanged = $anychanged || $changed; } foreach ($modinfo->get_section_info_all() as $section) { $info = new info_section($section); $changed = $info->update_dependency_id($table, $oldid, $newid); $anychanged = $anychanged || $changed; } $transaction->allow_commit(); if ($anychanged) { get_fast_modinfo($courseorid, 0, true); } return $anychanged; } /** * Called on a single item. If necessary, updates availability data where * it has a dependency on an item with a particular id. * * @param string $table Table name e.g. 'course_modules' * @param int $oldid Previous ID * @param int $newid New ID * @return bool True if it changed, otherwise false */ protected function update_dependency_id($table, $oldid, $newid) { // Do nothing if there are no availability restrictions. if (is_null($this->availability)) { return false; } // Pass requirement on to tree object. $tree = $this->get_availability_tree(); $changed = $tree->update_dependency_id($table, $oldid, $newid); if ($changed) { // Save modified data. $structure = $tree->save(); $this->set_in_database(json_encode($structure)); } return $changed; } /** * Converts legacy data from fields (if provided) into the new availability * syntax. * * Supported fields: availablefrom, availableuntil, showavailability * (and groupingid for sections). * * It also supports the groupmembersonly field for modules. This part was * optional in 2.7 but now always runs (because groupmembersonly has been * removed). * * @param \stdClass $rec Object possibly containing legacy fields * @param bool $section True if this is a section * @param bool $modgroupmembersonlyignored Ignored option, previously used * @return string|null New availability value or null if none */ public static function convert_legacy_fields($rec, $section, $modgroupmembersonlyignored = false) { // Do nothing if the fields are not set. if (empty($rec->availablefrom) && empty($rec->availableuntil) && (empty($rec->groupmembersonly)) && (!$section || empty($rec->groupingid))) { return null; } // Handle legacy availability data. $conditions = array(); $shows = array(); // Groupmembersonly condition (if enabled) for modules, groupingid for // sections. if (!empty($rec->groupmembersonly) || (!empty($rec->groupingid) && $section)) { if (!empty($rec->groupingid)) { $conditions[] = '{"type":"grouping"' . ($rec->groupingid ? ',"id":' . $rec->groupingid : '') . '}'; } else { // No grouping specified, so allow any group. $conditions[] = '{"type":"group"}'; } // Group members only condition was not displayed to students. $shows[] = 'false'; } // Date conditions. if (!empty($rec->availablefrom)) { $conditions[] = '{"type":"date","d":">=","t":' . $rec->availablefrom . '}'; $shows[] = !empty($rec->showavailability) ? 'true' : 'false'; } if (!empty($rec->availableuntil)) { $conditions[] = '{"type":"date","d":"<","t":' . $rec->availableuntil . '}'; // Until dates never showed to students. $shows[] = 'false'; } // If there are some conditions, return them. if ($conditions) { return '{"op":"&","showc":[' . implode(',', $shows) . '],' . '"c":[' . implode(',', $conditions) . ']}'; } else { return null; } } /** * Adds a condition from the legacy availability condition. * * (For use during restore only.) * * This function assumes that the activity either has no conditions, or * that it has an AND tree with one or more conditions. * * @param string|null $availability Current availability conditions * @param \stdClass $rec Object containing information from old table * @param bool $show True if 'show' option should be enabled * @return string New availability conditions */ public static function add_legacy_availability_condition($availability, $rec, $show) { if (!empty($rec->sourcecmid)) { // Completion condition. $condition = '{"type":"completion","cm":' . $rec->sourcecmid . ',"e":' . $rec->requiredcompletion . '}'; } else { // Grade condition. $minmax = ''; if (!empty($rec->grademin)) { $minmax .= ',"min":' . sprintf('%.5f', $rec->grademin); } if (!empty($rec->grademax)) { $minmax .= ',"max":' . sprintf('%.5f', $rec->grademax); } $condition = '{"type":"grade","id":' . $rec->gradeitemid . $minmax . '}'; } return self::add_legacy_condition($availability, $condition, $show); } /** * Adds a condition from the legacy availability field condition. * * (For use during restore only.) * * This function assumes that the activity either has no conditions, or * that it has an AND tree with one or more conditions. * * @param string|null $availability Current availability conditions * @param \stdClass $rec Object containing information from old table * @param bool $show True if 'show' option should be enabled * @return string New availability conditions */ public static function add_legacy_availability_field_condition($availability, $rec, $show) { if (isset($rec->userfield)) { // Standard field. $fieldbit = ',"sf":' . json_encode($rec->userfield); } else { // Custom field. $fieldbit = ',"cf":' . json_encode($rec->shortname); } // Value is not included for certain operators. switch($rec->operator) { case 'isempty': case 'isnotempty': $valuebit = ''; break; default: $valuebit = ',"v":' . json_encode($rec->value); break; } $condition = '{"type":"profile","op":"' . $rec->operator . '"' . $fieldbit . $valuebit . '}'; return self::add_legacy_condition($availability, $condition, $show); } /** * Adds a condition to an AND group. * * (For use during restore only.) * * This function assumes that the activity either has no conditions, or * that it has only conditions added by this function. * * @param string|null $availability Current availability conditions * @param string $condition Condition text '{...}' * @param bool $show True if 'show' option should be enabled * @return string New availability conditions */ protected static function add_legacy_condition($availability, $condition, $show) { $showtext = ($show ? 'true' : 'false'); if (is_null($availability)) { $availability = '{"op":"&","showc":[' . $showtext . '],"c":[' . $condition . ']}'; } else { $matches = array(); if (!preg_match('~^({"op":"&","showc":\[(?:true|false)(?:,(?:true|false))*)' . '(\],"c":\[.*)(\]})$~', $availability, $matches)) { throw new \coding_exception('Unexpected availability value'); } $availability = $matches[1] . ',' . $showtext . $matches[2] . ',' . $condition . $matches[3]; } return $availability; } /** * Tests against a user list. Users who cannot access the activity due to * availability restrictions will be removed from the list. * * Note this only includes availability restrictions (those handled within * this API) and not other ways of restricting access. * * This test ONLY includes conditions which are marked as being applied to * user lists. For example, group conditions are included but date * conditions are not included. * * The function operates reasonably efficiently i.e. should not do per-user * database queries. It is however likely to be fairly slow. * * @param array $users Array of userid => object * @return array Filtered version of input array */ public function filter_user_list(array $users) { global $CFG; if (is_null($this->availability) || !$CFG->enableavailability) { return $users; } $tree = $this->get_availability_tree(); $checker = new capability_checker($this->get_context()); // Filter using availability tree. $this->modinfo = get_fast_modinfo($this->get_course()); $filtered = $tree->filter_user_list($users, false, $this, $checker); $this->modinfo = null; // Include users in the result if they're either in the filtered list, // or they have viewhidden. This logic preserves ordering of the // passed users array. $result = array(); $canviewhidden = $checker->get_users_by_capability($this->get_view_hidden_capability()); foreach ($users as $userid => $data) { if (array_key_exists($userid, $filtered) || array_key_exists($userid, $canviewhidden)) { $result[$userid] = $users[$userid]; } } return $result; } /** * Gets the capability used to view hidden activities/sections (as * appropriate). * * @return string Name of capability used to view hidden items of this type */ protected abstract function get_view_hidden_capability(); /** * Obtains SQL that returns a list of enrolled users that has been filtered * by the conditions applied in the availability API, similar to calling * get_enrolled_users and then filter_user_list. As for filter_user_list, * this ONLY filters out users with conditions that are marked as applying * to user lists. For example, group conditions are included but date * conditions are not included. * * The returned SQL is a query that returns a list of user IDs. It does not * include brackets, so you neeed to add these to make it into a subquery. * You would normally use it in an SQL phrase like "WHERE u.id IN ($sql)". * * The function returns an array with '' and an empty array, if there are * no restrictions on users from these conditions. * * The SQL will be complex and may be slow. It uses named parameters (sorry, * I know they are annoying, but it was unavoidable here). * * @param bool $onlyactive True if including only active enrolments * @return array Array of SQL code (may be empty) and params */ public function get_user_list_sql($onlyactive) { global $CFG; if (is_null($this->availability) || !$CFG->enableavailability) { return array('', array()); } // Get SQL for the availability filter. $tree = $this->get_availability_tree(); list ($filtersql, $filterparams) = $tree->get_user_list_sql(false, $this, $onlyactive); if ($filtersql === '') { // No restrictions, so return empty query. return array('', array()); } // Get SQL for the view hidden list. list ($viewhiddensql, $viewhiddenparams) = get_enrolled_sql( $this->get_context(), $this->get_view_hidden_capability(), 0, $onlyactive); // Result is a union of the two. return array('(' . $filtersql . ') UNION (' . $viewhiddensql . ')', array_merge($filterparams, $viewhiddenparams)); } /** * Formats the $cm->availableinfo string for display. This includes * filling in the names of any course-modules that might be mentioned. * Should be called immediately prior to display, or at least somewhere * that we can guarantee does not happen from within building the modinfo * object. * * @param \renderable|string $inforenderable Info string or renderable * @param int|\stdClass $courseorid * @return string Correctly formatted info string */ public static function format_info($inforenderable, $courseorid) {
< global $PAGE;
> global $PAGE, $OUTPUT;
// Use renderer if required. if (is_string($inforenderable)) { $info = $inforenderable; } else {
< $renderer = $PAGE->get_renderer('core', 'availability'); < $info = $renderer->render($inforenderable);
> $renderable = new \core_availability\output\availability_info($inforenderable); > $info = $OUTPUT->render($renderable);
} // Don't waste time if there are no special tags. if (strpos($info, '<AVAILABILITY_') === false) { return $info; } // Handle CMNAME tags. $modinfo = get_fast_modinfo($courseorid); $context = \context_course::instance($modinfo->courseid); $info = preg_replace_callback('~<AVAILABILITY_CMNAME_([0-9]+)/>~', function($matches) use($modinfo, $context) { $cm = $modinfo->get_cm($matches[1]); if ($cm->has_view() and $cm->get_user_visible()) { // Help student by providing a link to the module which is preventing availability. return \html_writer::link($cm->get_url(), format_string($cm->get_name(), true, ['context' => $context])); } else { return format_string($cm->get_name(), true, ['context' => $context]); }
> }, $info); }, $info); > $info = preg_replace_callback('~<AVAILABILITY_FORMAT_STRING>(.*?)</AVAILABILITY_FORMAT_STRING>~s', > function($matches) use ($context) { return $info; > $decoded = htmlspecialchars_decode($matches[1], ENT_NOQUOTES); } > return format_string($decoded, true, ['context' => $context]); > }, $info); /** > $info = preg_replace_callback('~<AVAILABILITY_CALLBACK type="([a-z0-9_]+)">(.*?)</AVAILABILITY_CALLBACK>~s', * Used in course/lib.php because we need to disable the completion tickbox > function($matches) use ($modinfo, $context) { * JS (using the non-JS version instead, which causes a page reload) if a > // Find the class, it must have already been loaded by now. * completion tickbox value may affect a conditional activity. > $fullclassname = 'availability_' . $matches[1] . '\condition'; * > if (!class_exists($fullclassname, false)) { * @param \stdClass $course Moodle course object > return '<!-- Error finding class ' . $fullclassname .' -->'; * @param int $cmid Course-module id > } * @return bool True if this is used in a condition, false otherwise > // Load the parameters. */ > $params = []; public static function completion_value_used($course, $cmid) { > $encodedparams = preg_split('~<P/>~', $matches[2], 0); // Access all plugins. Normally only the completion plugin is going > foreach ($encodedparams as $encodedparam) { // to affect this value, but it's potentially possible that some other > $params[] = htmlspecialchars_decode($encodedparam, ENT_NOQUOTES); // plugin could also rely on the completion plugin. > } $pluginmanager = \core_plugin_manager::instance(); > return $fullclassname::get_description_callback_value($modinfo, $context, $params);
$enabled = $pluginmanager->get_enabled_plugins('availability'); $componentparams = new \stdClass(); foreach ($enabled as $plugin => $info) { // Use the static method. $class = '\availability_' . $plugin . '\condition'; if ($class::completion_value_used($course, $cmid)) { return true; } } return false; } }