Merged new functions for get_courses and get_courses_page from STABLE

diff --git a/lib/datalib.php b/lib/datalib.php
index 5d0b00d359039f12f8089c43fa17cc3276e9ca29..07e2dd299ed41fd48a26582d76899910c1600b4d 100644 (file)
--- a/lib/datalib.php
+++ b/lib/datalib.php
@@ -1775,37 +1775,51 @@ function get_site () {
 * @todo Finish documenting this function
 */
 function get_courses($categoryid='all', $sort='c.sortorder ASC', $fields='c.*') {
+/// This function deliberately uses PHP to do the checking at the end, 
+/// because MySQL has been known to really bog down when trying to do a JOIN
+/// on the 'course' and 'user_teachers' table at the same time.
 
     global $USER, $CFG;
 
-    $categoryselect = '';
+    $select = array();
+
     if ($categoryid != 'all') {
-        $categoryselect = 'c.category = \''. $categoryid .'\'';
+        $select[] = "c.category = '$categoryid'";
     }
 
-    $teachertable = '';
+    /// Admins can always see invisible courses
+    /// Creators can always see invisible courses
+    /// Teachers can only see their own invisible courses  <- needs detailed checking
+    /// Students can't see invisible courses at all
+    /// Guests can't see invisible courses at all
+
     $visiblecourses = '';
-    $sqland = '';
-    if (!empty($categoryselect)) {
-        $sqland = 'AND ';
-    }
-    if (!empty($USER->id)) {  // May need to check they are a teacher
-        if (!iscreator()) {
-            $visiblecourses = $sqland .' ((c.visible > 0) OR (t.userid = \''. $USER->id .'\' AND t.course = c.id))';
-            $teachertable = ', '. $CFG->prefix .'user_teachers t';
-        }
-    } else {
-        $visiblecourses = $sqland .' c.visible > 0';
+    $showallinvisible = iscreator();     // includes admins
+    $hideallinvisible = empty($USER->id) || (!isteacher());
+
+    if ($hideallinvisible) {
+        $select[] = 'c.visible > 0';
     }
 
-    if ($categoryselect or $visiblecourses) {
-        $selectsql = $CFG->prefix .'course c '. $teachertable .' WHERE '. $categoryselect .' '. $visiblecourses;
+    if ($select) {
+        $selectsql = "{$CFG->prefix}course c WHERE ".implode(' AND ', $select);
     } else {
-        $selectsql = $CFG->prefix .'course c '. $teachertable;
+        $selectsql = "{$CFG->prefix}course c ";
     }
 
+    $courses = get_records_sql("SELECT DISTINCT $fields FROM $selectsql ORDER BY $sort");
 
-    return get_records_sql('SELECT DISTINCT '. $fields .' FROM '. $selectsql .' ORDER BY '. $sort);
+    if ($courses and (!$hideallinvisible) and (!$showallinvisible)) { // For ordinary users we need to check visibility
+        foreach ($courses as $key => $course) {
+            if ($course->visible == 0) {          // Invisible course, let's check if we are a teacher
+                if (!isteacher($course->id)) {    // We shouldn't see this
+                    unset($courses[$key]);
+                }
+            }
+        }
+    }
+
+    return $courses;
 }
 
 
@@ -1815,53 +1829,61 @@ function get_courses($categoryid='all', $sort='c.sortorder ASC', $fields='c.*')
 * Similar to get_courses, but allows paging
 *
 * @param    type description
-* @todo Finish documenting this function
 */
 function get_courses_page($categoryid='all', $sort='c.sortorder ASC', $fields='c.*',
                           &$totalcount, $limitfrom='', $limitnum='') {
 
+/// This function deliberately uses PHP to do the checking at the end, 
+/// because MySQL has been known to really bog down when trying to do a JOIN
+/// on the 'course' and 'user_teachers' table at the same time.
+
     global $USER, $CFG;
 
-    $categoryselect = '';
+    $select = array();
+
     if ($categoryid != 'all') {
-        $categoryselect = 'c.category = \''. $categoryid .'\'';
+        $select[] = "c.category = '$categoryid'";
     }
 
-    $teachertable = '';
+    /// Admins can always see invisible courses
+    /// Creators can always see invisible courses
+    /// Teachers can only see their own invisible courses  <- needs detailed checking
+    /// Students can't see invisible courses at all
+    /// Guests can't see invisible courses at all
+
     $visiblecourses = '';
-    $sqland = '';
-    if (!empty($categoryselect)) {
-        $sqland = 'AND ';
-    }
-    if (!empty($USER)) {  // May need to check they are a teacher
-        if (!iscreator()) {
-            $visiblecourses = $sqland .' ((c.visible > 0) OR (t.userid = \''. $USER->id .'\' AND t.course = c.id))';
-            $teachertable = ', '. $CFG->prefix .'user_teachers t';
-        }
+    $showallinvisible = iscreator();     // includes admins
+    $hideallinvisible = empty($USER->id) || (!isteacher());
+
+    if ($hideallinvisible) {
+        $select[] = 'c.visible > 0';
+    }
+
+    if ($select) {
+        $selectsql = "{$CFG->prefix}course c WHERE ".implode(' AND ', $select);
     } else {
-        $visiblecourses = $sqland .' c.visible > 0';
+        $selectsql = "{$CFG->prefix}course c ";
     }
 
-    if ($limitfrom !== '') {
-        switch ($CFG->dbtype) {
-            case 'mysql':
-                 $limit = 'LIMIT '. $limitfrom .','. $limitnum;
-                 break;
-            case 'postgres7':
-                 $limit = 'LIMIT '. $limitnum .' OFFSET '. $limitfrom;
-                 break;
-            default:
-                 $limit = 'LIMIT '. $limitnum .','. $limitfrom;
+    $courses = get_records_sql("SELECT DISTINCT $fields FROM $selectsql ORDER BY $sort");
+
+    if ($courses and (!$hideallinvisible) and (!$showallinvisible)) { // For ordinary users we need to check visibility
+        foreach ($courses as $key => $course) {
+            if ($course->visible == 0) {          // Invisible course, let's check if we are a teacher
+                if (!isteacher($course->id)) {    // We shouldn't see this
+                    unset($courses[$key]);
+                }
+            }
         }
-    } else {
-        $limit = '';
     }
 
-    $selectsql = $CFG->prefix .'course c '. $teachertable .' WHERE '. $categoryselect .' '. $visiblecourses;
+    $totalcount = count($courses);
 
-    $totalcount = count_records_sql('SELECT COUNT(DISTINCT c.id) FROM '. $selectsql);
+    if ($courses and ($limitfrom or $limitnum)) {
+        $courses = array_slice($courses, (int)$limitfrom, (int)$limitnum);
+    }
 
-    return get_records_sql('SELECT DISTINCT '. $fields .' FROM '. $selectsql .' ORDER BY '. $sort .' '. $limit);
+    return $courses;
 }