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accesslib: get_context_users_bycap() draft for course participants...

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Introducing get_context_users_bycap() which gets the data in
2 DB queries, takes around 10ms on my laptop, and returns
the records with a nice context property attached.

Note Note Note: right now, some user recs do not have a context
associated, so are _not_ returned. So this awaits Matt's fix
to contexts maintenance to be 100% accurate...
This commit is contained in:
martinlanghoff 2007-09-19 07:07:45 +00:00
parent fe3141e00b
commit 4d8ab2749e
1 changed files with 118 additions and 0 deletions
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118
lib/accesslib.php
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@ -921,6 +921,124 @@ function get_context_users_byrole ($context, $roleid, $fields=NULL, $where=NULL,
return $users;
}
/*
* Draft - use for the course participants list page
*
* Uses 2 fast DB queries
*
* TODO:
* - automagically exclude roles that can-doanything sitewide (See callers)
* - perhaps also allow sitewide do-anything via flag
* - implement additional where clauses
* - sorting
* - get course participants list to use it!
*
* returns a users array, both sorted _and_ keyed
* on id (as get_my_courses() does)
*
* as a bonus, every user record comes with its own
* personal context, as our callers need it straight away
* {save 1 dbquery per user! yay!}
*
*/
function get_context_users_bycap ($context, $capability='moodle/course:view', $fields=NULL, $where=NULL, $sort=NULL, $limit=0) {
global $CFG;
// Plan
//
// - Get all the *interesting* roles -- those that
// have some rolecap entry in our ctx.path contexts
//
// - Get all RAs for any of those roles in any of our
// interesting contexts, with userid & perm data
// in a nice (per user?) order
//
// - Walk the resultset, computing the permissions
// - actually - this is all a SQL subselect
//
// - Fetch user records against the subselect
//
// Slim base fields, let callers ask for what they need...
$basefields = array('id', 'username');
if (!is_null($fields)) {
$fields = array_merge($basefields, $fields);
$fields = array_unique($fields);
} else {
$fields = $basefields;
}
$userfields = 'u.' .join(',u.', $fields);
$contexts = substr($context->path, 1); // kill leading slash
$contexts = str_replace('/', ',', $contexts);
$roles = array();
$sql = "SELECT DISTINCT rc.roleid
FROM {$CFG->prefix}role_capabilities rc
WHERE rc.capability = '$capability'
AND rc.contextid IN ($contexts)";
$rs = get_recordset_sql($sql);
if ($rs->RecordCount()) {
while ($u = rs_fetch_next_record($rs)) {
$roles[] = $u->roleid;
}
}
rs_close($rs);
$roles = join(',', $roles);
//
// User permissions subselect SQL
//
// - the open join condition to
// role_capabilities
//
// - because both rc and ra entries are
// _at or above_ our context, we don't care
// about their depth, we just need to sum them
//
$sql = "SELECT ra.userid, SUM(rc.permission) AS permission
FROM {$CFG->prefix}role_assignments ra
JOIN {$CFG->prefix}role_capabilities rc
ON (ra.roleid = rc.roleid AND rc.contextid IN ($contexts))
WHERE ra.contextid IN ($contexts)
AND ra.roleid IN ($roles)
GROUP BY ra.userid";
// Get users
$sql = "SELECT $userfields,
ctx.id AS ctxid, ctx.path AS ctxpath, ctx.depth as ctxdepth
FROM {$CFG->prefix}user u
JOIN {$CFG->prefix}context ctx
ON (u.id=ctx.instanceid AND ctx.contextlevel=".CONTEXT_USER.")
JOIN ($sql) up
ON u.id = up.userid
WHERE up.permission > 0 AND u.username != 'guest'";
$rs = get_recordset_sql($sql);
$users = array();
$cc = 0; // keep count
if ($rs->RecordCount()) {
while ($u = rs_fetch_next_record($rs)) {
// build the context obj
$ctx = new StdClass;
$ctx->id = $u->ctxid; unset($u->ctxid);
$ctx->path = $u->ctxpath; unset($u->ctxpath);
$ctx->depth = $u->ctxdepth; unset($u->ctxdepth);
$ctx->instanceid = $u->id;
$ctx->contextlevel = CONTEXT_USER;
$u->context = $ctx;
$users[] = $u;
if ($limit > 0 && $cc++ > $limit) {
break;
}
}
}
rs_close($rs);
return $users;
}
/**
* It will return a nested array showing role assignments
* all relevant role capabilities for the user at