/**
* Recursive function which, given a context, find all its children context ids.
*
* When called for a course context, it will return the modules and blocks
* displayed in the course page.
*
* For course category contexts it will return categories and courses. It will
* NOT recurse into courses - if you want to do that, call it on the returned
* courses.
*
* If called on a course context it _will_ populate the cache with the appropriate
* contexts ;-)
*
* @param object $context.
* @return array of child records
*/
function get_child_contexts($context)
{
global $DB, $ACCESSLIB_PRIVATE;
// We *MUST* populate the context_cache as the callers
// will probably ask for the full record anyway soon after
// soon after calling us ;-)
switch ($context->contextlevel) {
case CONTEXT_BLOCK:
// No children.
return array();
break;
case CONTEXT_MODULE:
// No children.
return array();
break;
case CONTEXT_COURSE:
// Find
// - module instances - easy
// - blocks assigned to the course-view page explicitly - easy
$sql = " SELECT ctx.*\n FROM {context} ctx\n WHERE ctx.path LIKE ?\n AND ctx.contextlevel IN (" . CONTEXT_MODULE . "," . CONTEXT_BLOCK . ")";
$params = array("{$context->path}/%", $context->instanceid);
$records = $DB->get_recordset_sql($sql, $params);
foreach ($records as $rec) {
cache_context($rec);
}
return $records;
break;
case CONTEXT_COURSECAT:
// Find
// - categories
// - courses
$sql = " SELECT ctx.*\n FROM {context} ctx\n WHERE ctx.path LIKE ?\n AND ctx.contextlevel IN (" . CONTEXT_COURSECAT . "," . CONTEXT_COURSE . ")";
$params = array("{$context->path}/%");
$records = $DB->get_recordset_sql($sql, $params);
foreach ($records as $rec) {
cache_context($rec);
}
return $records;
break;
case CONTEXT_USER:
// No children.
return array();
break;
case CONTEXT_SYSTEM:
// Just get all the contexts except for CONTEXT_SYSTEM level
// and hope we don't OOM in the process - don't cache
$sql = "SELECT c.*\n FROM {context} c\n WHERE contextlevel != " . CONTEXT_SYSTEM;
return $DB->get_records_sql($sql);
break;
default:
print_error('unknowcontext', '', '', $context->contextlevel);
return false;
}
}
/**
* Get a context instance as an object, from a given context id.
* @param mixed $id a context id or array of ids.
* @return mixed object or array of the context object.
*/
function get_context_instance_by_id($id)
{
global $context_cache, $context_cache_id;
if ($id == SYSCONTEXTID) {
return get_system_context();
}
if (isset($context_cache_id[$id])) {
// Already cached
return $context_cache_id[$id];
}
if ($context = get_record('context', 'id', $id)) {
// Update the cache and return
cache_context($context);
return $context;
}
return false;
}
