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<?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/>.
/**
* Search area base class for blocks.
*
* Note: Only blocks within courses are supported.
*
* @package core_search
* @copyright 2017 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core_search;
defined('MOODLE_INTERNAL') || die();
/**
* Search area base class for blocks.
*
* Note: Only blocks within courses are supported.
*
* @package core_search
* @copyright 2017 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class base_block extends base {
/** @var string Cache name used for block instances */
const CACHE_INSTANCES = 'base_block_instances';
/**
* The context levels the search area is working on.
*
* This can be overwriten by the search area if it works at multiple
* levels.
*
* @var array
*/
protected static $levels = [CONTEXT_BLOCK];
/**
* Gets the block name only.
*
* @return string Block name e.g. 'html'
*/
public function get_block_name() {
// Remove 'block_' text.
return substr($this->get_component_name(), 6);
}
/**
* Returns restrictions on which block_instances rows to return. By default, excludes rows
* that have empty configdata.
*
* If no restriction is required, you could return ['', []].
*
* @return array 2-element array of SQL restriction and params for it
*/
protected function get_indexing_restrictions() {
global $DB;
// This includes completely empty configdata, and also three other values that are
// equivalent to empty:
// - A serialized completely empty object.
// - A serialized object with one field called '0' (string not int) set to boolean false
// (this can happen after backup and restore, at least historically).
// - A serialized null.
$stupidobject = (object)[];
$zero = '0';
$stupidobject->{$zero} = false;
return [$DB->sql_compare_text('bi.configdata') . " != ? AND " .
$DB->sql_compare_text('bi.configdata') . " != ? AND " .
$DB->sql_compare_text('bi.configdata') . " != ? AND " .
$DB->sql_compare_text('bi.configdata') . " != ?",
['', base64_encode(serialize((object)[])), base64_encode(serialize($stupidobject)),
base64_encode(serialize(null))]];
}
/**
* Gets recordset of all blocks of this type modified since given time within the given context.
*
* See base class for detailed requirements. This implementation includes the key fields
* from block_instances.
*
* This can be overridden to do something totally different if the block's data is stored in
* other tables.
*
* If there are certain instances of the block which should not be included in the search index
* then you can override get_indexing_restrictions; by default this excludes rows with empty
* configdata.
*
* @param int $modifiedfrom Return only records modified after this date
* @param \context|null $context Context to find blocks within
* @return false|\moodle_recordset|null
*/
public function get_document_recordset($modifiedfrom = 0, \context $context = null) {
global $DB;
// Get context restrictions.
list ($contextjoin, $contextparams) = $this->get_context_restriction_sql($context, 'bi');
// Get custom restrictions for block type.
list ($restrictions, $restrictionparams) = $this->get_indexing_restrictions();
if ($restrictions) {
$restrictions = 'AND ' . $restrictions;
}
// Query for all entries in block_instances for this type of block, within the specified
// context. The query is based on the one from get_recordset_by_timestamp and applies the
// same restrictions.
return $DB->get_recordset_sql("
SELECT bi.id, bi.timemodified, bi.timecreated, bi.configdata,
c.id AS courseid, x.id AS contextid
FROM {block_instances} bi
$contextjoin
JOIN {context} x ON x.instanceid = bi.id AND x.contextlevel = ?
JOIN {context} parent ON parent.id = bi.parentcontextid
LEFT JOIN {course_modules} cm ON cm.id = parent.instanceid AND parent.contextlevel = ?
JOIN {course} c ON c.id = cm.course
OR (c.id = parent.instanceid AND parent.contextlevel = ?)
WHERE bi.timemodified >= ?
AND bi.blockname = ?
AND (parent.contextlevel = ? AND (" . $DB->sql_like('bi.pagetypepattern', '?') . "
OR bi.pagetypepattern IN ('site-index', 'course-*', '*')))
$restrictions
ORDER BY bi.timemodified ASC",
array_merge($contextparams, [CONTEXT_BLOCK, CONTEXT_MODULE, CONTEXT_COURSE,
$modifiedfrom, $this->get_block_name(), CONTEXT_COURSE, 'course-view-%'],
$restrictionparams));
}
public function get_doc_url(\core_search\document $doc) {
// Load block instance and find cmid if there is one.
$blockinstanceid = preg_replace('~^.*-~', '', $doc->get('id'));
$instance = $this->get_block_instance($blockinstanceid);
$courseid = $doc->get('courseid');
$anchor = 'inst' . $blockinstanceid;
// Check if the block is at course or module level.
if ($instance->cmid) {
// No module-level page types are supported at present so the search system won't return
// them. But let's put some example code here to indicate how it could work.
debugging('Unexpected module-level page type for block ' . $blockinstanceid . ': ' .
$instance->pagetypepattern, DEBUG_DEVELOPER);
$modinfo = get_fast_modinfo($courseid);
$cm = $modinfo->get_cm($instance->cmid);
return new \moodle_url($cm->url, null, $anchor);
} else {
// The block is at course level. Let's check the page type, although in practice we
// currently only support the course main page.
if ($instance->pagetypepattern === '*' || $instance->pagetypepattern === 'course-*' ||
preg_match('~^course-view-(.*)$~', $instance->pagetypepattern)) {
return new \moodle_url('/course/view.php', ['id' => $courseid], $anchor);
} else if ($instance->pagetypepattern === 'site-index') {
return new \moodle_url('/', ['redirect' => 0], $anchor);
} else {
debugging('Unexpected page type for block ' . $blockinstanceid . ': ' .
$instance->pagetypepattern, DEBUG_DEVELOPER);
return new \moodle_url('/course/view.php', ['id' => $courseid], $anchor);
}
}
}
public function get_context_url(\core_search\document $doc) {
return $this->get_doc_url($doc);
}
/**
* Checks access for a document in this search area.
*
* If you override this function for a block, you should call this base class version first
* as it will check that the block is still visible to users in a supported location.
*
* @param int $id Document id
* @return int manager:ACCESS_xx constant
*/
public function check_access($id) {
$instance = $this->get_block_instance($id, IGNORE_MISSING);
if (!$instance) {
// This generally won't happen because if the block has been deleted then we won't have
// included its context in the search area list, but just in case.
return manager::ACCESS_DELETED;
}
// Check block has not been moved to an unsupported area since it was indexed. (At the
// moment, only blocks within site and course context are supported, also only certain
// page types.)
if (!$instance->courseid ||
!self::is_supported_page_type_at_course_context($instance->pagetypepattern)) {
return manager::ACCESS_DELETED;
}
// Note we do not need to check if the block was hidden or if the user has access to the
// context, because those checks are included in the list of search contexts user can access
// that is calculated in manager.php every time they do a query.
return manager::ACCESS_GRANTED;
}
/**
* Checks if a page type is supported for blocks when at course (or also site) context. This
* function should be consistent with the SQL in get_recordset_by_timestamp.
*
* @param string $pagetype Page type
* @return bool True if supported
*/
protected static function is_supported_page_type_at_course_context($pagetype) {
if (in_array($pagetype, ['site-index', 'course-*', '*'])) {
return true;
}
if (preg_match('~^course-view-~', $pagetype)) {
return true;
}
return false;
}
/**
* Gets a block instance with given id.
*
* Returns the fields id, pagetypepattern, subpagepattern from block_instances and also the
* cmid (if parent context is an activity module).
*
* @param int $id ID of block instance
* @param int $strictness MUST_EXIST or IGNORE_MISSING
* @return false|mixed Block instance data (may be false if strictness is IGNORE_MISSING)
*/
protected function get_block_instance($id, $strictness = MUST_EXIST) {
global $DB;
$cache = \cache::make_from_params(\cache_store::MODE_REQUEST, 'core_search',
self::CACHE_INSTANCES, [], ['simplekeys' => true]);
$id = (int)$id;
$instance = $cache->get($id);
if (!$instance) {
$instance = $DB->get_record_sql("
SELECT bi.id, bi.pagetypepattern, bi.subpagepattern,
c.id AS courseid, cm.id AS cmid
FROM {block_instances} bi
JOIN {context} parent ON parent.id = bi.parentcontextid
LEFT JOIN {course} c ON c.id = parent.instanceid AND parent.contextlevel = ?
LEFT JOIN {course_modules} cm ON cm.id = parent.instanceid AND parent.contextlevel = ?
WHERE bi.id = ?",
[CONTEXT_COURSE, CONTEXT_MODULE, $id], $strictness);
$cache->set($id, $instance);
}
return $instance;
}
/**
* Clears static cache. This function can be removed (with calls to it in the test script
* replaced with cache_helper::purge_all) if MDL-59427 is fixed.
*/
public static function clear_static() {
\cache::make_from_params(\cache_store::MODE_REQUEST, 'core_search',
self::CACHE_INSTANCES, [], ['simplekeys' => true])->purge();
}
/**
* Helper function that gets SQL useful for restricting a search query given a passed-in
* context.
*
* The SQL returned will be one or more JOIN statements, surrounded by whitespace, which act
* as restrictions on the query based on the rows in the block_instances table.
*
* We assume the block instances have already been restricted by blockname.
*
* Returns null if there can be no results for this block within this context.
*
* If named parameters are used, these will be named gcrs0, gcrs1, etc. The table aliases used
* in SQL also all begin with gcrs, to avoid conflicts.
*
* @param \context|null $context Context to restrict the query
* @param string $blocktable Alias of block_instances table
* @param int $paramtype Type of SQL parameters to use (default question mark)
* @return array Array with SQL and parameters
* @throws \coding_exception If called with invalid params
*/
protected function get_context_restriction_sql(\context $context = null, $blocktable = 'bi',
$paramtype = SQL_PARAMS_QM) {
global $DB;
if (!$context) {
return ['', []];
}
switch ($paramtype) {
case SQL_PARAMS_QM:
$param1 = '?';
$param2 = '?';
$key1 = 0;
$key2 = 1;
break;
case SQL_PARAMS_NAMED:
$param1 = ':gcrs0';
$param2 = ':gcrs1';
$key1 = 'gcrs0';
$key2 = 'gcrs1';
break;
default:
throw new \coding_exception('Unexpected $paramtype: ' . $paramtype);
}
$params = [];
switch ($context->contextlevel) {
case CONTEXT_SYSTEM:
$sql = '';
break;
case CONTEXT_COURSECAT:
case CONTEXT_COURSE:
case CONTEXT_MODULE:
case CONTEXT_USER:
// Find all blocks whose parent is within the specified context.
$sql = " JOIN {context} gcrsx ON gcrsx.id = $blocktable.parentcontextid
AND (gcrsx.id = $param1 OR " . $DB->sql_like('gcrsx.path', $param2) . ") ";
$params[$key1] = $context->id;
$params[$key2] = $context->path . '/%';
break;
case CONTEXT_BLOCK:
// Find only the specified block of this type. Since we are generating JOINs
// here, we do this by joining again to the block_instances table with the same ID.
$sql = " JOIN {block_instances} gcrsbi ON gcrsbi.id = $blocktable.id
AND gcrsbi.id = $param1 ";
$params[$key1] = $context->instanceid;
break;
default:
throw new \coding_exception('Unexpected contextlevel: ' . $context->contextlevel);
}
return [$sql, $params];
}
/**
* This can be used in subclasses to change ordering within the get_contexts_to_reindex
* function.
*
* It returns 2 values:
* - Extra SQL joins (tables block_instances 'bi' and context 'x' already exist).
* - An ORDER BY value which must use aggregate functions, by default 'MAX(bi.timemodified) DESC'.
*
* Note the query already includes a GROUP BY on the context fields, so if your joins result
* in multiple rows, you can use aggregate functions in the ORDER BY. See forum for an example.
*
* @return string[] Array with 2 elements; extra joins for the query, and ORDER BY value
*/
protected function get_contexts_to_reindex_extra_sql() {
return ['', 'MAX(bi.timemodified) DESC'];
}
/**
* Gets a list of all contexts to reindex when reindexing this search area.
*
* For blocks, the default is to return all contexts for blocks of that type, that are on a
* course page, in order of time added (most recent first).
*
* @return \Iterator Iterator of contexts to reindex
* @throws \moodle_exception If any DB error
*/
public function get_contexts_to_reindex() {
global $DB;
list ($extrajoins, $dborder) = $this->get_contexts_to_reindex_extra_sql();
$contexts = [];
$selectcolumns = \context_helper::get_preload_record_columns_sql('x');
$groupbycolumns = '';
foreach (\context_helper::get_preload_record_columns('x') as $column => $thing) {
if ($groupbycolumns !== '') {
$groupbycolumns .= ',';
}
$groupbycolumns .= $column;
}
$rs = $DB->get_recordset_sql("
SELECT $selectcolumns
FROM {block_instances} bi
JOIN {context} x ON x.instanceid = bi.id AND x.contextlevel = ?
JOIN {context} parent ON parent.id = bi.parentcontextid
$extrajoins
WHERE bi.blockname = ? AND parent.contextlevel = ?
GROUP BY $groupbycolumns
ORDER BY $dborder", [CONTEXT_BLOCK, $this->get_block_name(), CONTEXT_COURSE]);
return new \core\dml\recordset_walk($rs, function($rec) {
$id = $rec->ctxid;
\context_helper::preload_from_record($rec);
return \context::instance_by_id($id);
});
}
/**
* Returns an icon instance for the document.
*
* @param \core_search\document $doc
* @return \core_search\document_icon
*/
public function get_doc_icon(document $doc) : document_icon {
return new document_icon('e/anchor');
}
/**
* Returns a list of category names associated with the area.
*
* @return array
*/
public function get_category_names() {
return [manager::SEARCH_AREA_CATEGORY_COURSE_CONTENT];
}
}