From 40fb8aa69ab25afd018300467db3c8c3f216c90c Mon Sep 17 00:00:00 2001
From: martinlanghoff <martinlanghoff>
Date: Wed, 19 Sep 2007 07:27:20 +0000
Subject: [PATCH] datalib: get_categories() returns context, supports !shallow

With this patch, get_categories() now adds a nice context
sub-object to the returned object, which means callers can
save DB traffic.

It now also supports "deep" retrievals, which means we can
rewrite the course categories display pages to avoid
costly recursion.
---
 lib/datalib.php | 62 +++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 52 insertions(+), 10 deletions(-)

diff --git a/lib/datalib.php b/lib/datalib.php
index a81044a387..ec489af32d 100644
--- a/lib/datalib.php
+++ b/lib/datalib.php
@@ -1158,25 +1158,67 @@ function get_courses_search($searchterms, $sort='fullname ASC', $page=0, $record
 
 
 /**
- * Returns a sorted list of categories
+ * Returns a sorted list of categories. Each category object has a context
+ * property that is a context object.
+ * 
+ * When asking for $parent='none' it will return all the categories, regardless
+ * of depth. Wheen asking for a specific parent, the default is to return
+ * a "shallow" resultset. Pass false to $shallow and it will return all
+ * the child categories as well. 
+ * 
  *
  * @param string $parent The parent category if any
  * @param string $sort the sortorder
+ * @param bool   $shallow - set to false to get the children too
  * @return array of categories
  */
-function get_categories($parent='none', $sort='sortorder ASC') {
+function get_categories($parent='none', $sort=NULL, $shallow=true) {
+    global $CFG;
+
+    if ($sort === NULL) {
+        $sort = 'ORDER BY cc.sortorder ASC';
+    } elseif ($sort ==='') {
+        // leave it as empty
+    } else {
+        $sort = "ORDER BY $sort";
+    }
 
     if ($parent === 'none') {
-        $categories = get_records('course_categories', '', '', $sort);
+        $sql = "SELECT cc.*,
+                      ctx.id AS ctxid, ctx.path AS ctxpath, ctx.depth as ctxdepth
+                FROM {$CFG->prefix}course_categories cc
+                JOIN {$CFG->prefix}context ctx
+                  ON cc.id=ctx.instanceid AND ctx.contextlevel=".CONTEXT_COURSECAT."
+                $sort";
+    } elseif ($shallow) {
+        $parent = (int)$parent;
+        $sql = "SELECT cc.*,
+                       ctx.id AS ctxid, ctx.path AS ctxpath, ctx.depth as ctxdepth
+                FROM {$CFG->prefix}course_categories cc
+                JOIN {$CFG->prefix}context ctx
+                  ON cc.id=ctx.instanceid AND ctx.contextlevel=".CONTEXT_COURSECAT."
+                WHERE cc.parent=$parent
+                $sort";
     } else {
-        $categories = get_records('course_categories', 'parent', $parent, $sort);
+        $parent = (int)$parent;
+        $sql = "SELECT cc.*,
+                       ctx.id AS ctxid, ctx.path AS ctxpath, ctx.depth as ctxdepth
+                FROM {$CFG->prefix}course_categories cc
+                JOIN {$CFG->prefix}context ctx
+                  ON cc.id=ctx.instanceid AND ctx.contextlevel=".CONTEXT_COURSECAT."
+                JOIN {$CFG->prefix}course_categories ccp
+                     ON (cc.path LIKE ccp.path||'%')
+                WHERE ccp.id=$parent
+                $sort";
     }
-    if ($categories) {  /// Remove unavailable categories from the list
-        foreach ($categories as $key => $category) {
-            if (!$category->visible) {
-                if (!has_capability('moodle/course:create', get_context_instance(CONTEXT_COURSECAT, $category->id))) {
-                    unset($categories[$key]);
-                }
+    $categories = array();
+
+    $rs = get_recordset_sql($sql);
+    if ($rs->RecordCount()) {
+        while ($cat = rs_fetch_next_record($rs)) {
+            $cat = make_context_subobj($cat);
+            if ($cat->visible || has_capability('moodle/course:create',$cat->context)) {
+                $categories[$cat->id] = $cat;
             }
         }
     }
-- 
2.39.5