Only send contexts to cache if the aren't empty. At initial installations

some empty contexts were being cached and used later, causing insertion
of null values to every DB but MySQL.

diff --git a/lib/accesslib.php b/lib/accesslib.php
index eac0d5adc20641478e93f59146dc114b740c24dd..ad307a9dfcb1840f3dafa34411c044248f974733 100755 (executable)
--- a/lib/accesslib.php
+++ b/lib/accesslib.php
@@ -977,10 +977,11 @@ function get_context_instance($aggregatelevel=NULL, $instance=SITEID) {
         $context = get_record('context', 'aggregatelevel', $aggregatelevel, 'instanceid', $instance);
     }
 
-/// Update the cache
-    $context_cache[$aggregatelevel][$instance] = $context;    // Cache it for later
-    $context_cache_id[$context->id] = $context;      // Cache it for later
-
+/// Only add to cache if context isn't empty.
+    if (!empty($context)) {
+        $context_cache[$aggregatelevel][$instance] = $context;    // Cache it for later
+        $context_cache_id[$context->id] = $context;      // Cache it for later
+    }
 
     return $context;
 }