1 files changed, 70 insertions, 27 deletions

diff --git a/modules/gallery/models/item.php b/modules/gallery/models/item.php
index a87997c6..ff02daf8 100644
--- a/modules/gallery/models/item.php
+++ b/modules/gallery/models/item.php
@@ -412,39 +412,74 @@ class Item_Model extends ORM_MPTT {
    * Find the position of the given child id in this album.  The resulting value is 1-indexed, so
    * the first child in the album is at position 1.
    */
-  public function get_position($child_id) {
+  public function get_position($child) {
     if ($this->sort_order == "DESC") {
       $comp = ">";
     } else {
       $comp = "<";
     }
-
     $db = Database::instance();
-    $position = $db->query("
-      SELECT COUNT(*) AS position FROM {items}
-      WHERE `parent_id` = {$this->id}
-        AND `{$this->sort_column}` $comp (SELECT `{$this->sort_column}`
-                                          FROM {items} WHERE `id` = $child_id)")
-      ->current()->position;
-
-    // We stopped short of our target value in the sort (notice that we're using a < comparator
-    // above) because it's possible that we have duplicate values in the sort column.  An
-    // equality check would just arbitrarily pick one of those multiple possible equivalent
-    // columns, which would mean that if you choose a sort order that has duplicates, it'd pick
-    // any one of them as the child's "position".
-    //
-    // Fix this by doing a 2nd query where we iterate over the equivalent columns and add them to
-    // our base value.
-    $result = $db->query("
-      SELECT id FROM {items}
-      WHERE `parent_id` = {$this->id}
-        AND `{$this->sort_column}` = (SELECT `{$this->sort_column}`
-                                      FROM {items} WHERE `id` = $child_id)
-      ORDER BY `id` ASC");
-    foreach ($result as $row) {
-      $position++;
-      if ($row->id == $child_id) {
-        break;
+
+    // If the comparison column has NULLs in it, we can't use comparators on it and will have to
+    // deal with it the hard way.
+    $count = $db->from("items")
+      ->where("parent_id", $this->id)
+      ->where($this->sort_column, NULL)
+      ->count_records();
+
+    if (empty($count)) {
+      // There are no NULLs in the sort column, so we can just use it directly.
+      $position = $db->query("
+        SELECT COUNT(*) AS position FROM {items}
+        WHERE `parent_id` = {$this->id}
+          AND `{$this->sort_column}` $comp (SELECT `{$this->sort_column}`
+                                            FROM {items} WHERE `id` = $child->id)")
+        ->current()->position;
+
+      // We stopped short of our target value in the sort (notice that we're using a < comparator
+      // above) because it's possible that we have duplicate values in the sort column.  An
+      // equality check would just arbitrarily pick one of those multiple possible equivalent
+      // columns, which would mean that if you choose a sort order that has duplicates, it'd pick
+      // any one of them as the child's "position".
+      //
+      // Fix this by doing a 2nd query where we iterate over the equivalent columns and add them to
+      // our base value.
+      $result = $db->query("
+        SELECT id FROM {items}
+        WHERE `parent_id` = {$this->id}
+          AND `{$this->sort_column}` = (SELECT `{$this->sort_column}`
+                                        FROM {items} WHERE `id` = $child->id)
+        ORDER BY `id` ASC");
+      foreach ($result as $row) {
+        $position++;
+        if ($row->id == $child->id) {
+          break;
+        }
+      }
+    } else {
+      // There are NULLs in the sort column, so we can't use MySQL comparators.  Fall back to
+      // iterating over every child row to get to the current one.  This can be wildly inefficient
+      // for really large albums, but it should be a rare case that the user is sorting an album
+      // with null values in the sort column.
+      //
+      // Reproduce the children() functionality here using Database directly to avoid loading the
+      // whole ORM for each row.
+      $orderby = array($this->sort_column => $this->sort_order);
+      // Use id as a tie breaker
+      if ($this->sort_column != "id") {
+        $orderby["id"] = "ASC";
+      }
+
+      $position = 0;
+      foreach ($db->select("id")
+               ->from("items")
+               ->where("parent_id", $this->id)
+               ->orderby($orderby)
+               ->get() as $row) {
+        $position++;
+        if ($row->id == $child->id) {
+          break;
+        }
       }
     }
 
@@ -551,6 +586,10 @@ class Item_Model extends ORM_MPTT {
   function children($limit=null, $offset=0, $where=array(), $orderby=null) {
     if (empty($orderby)) {
       $orderby = array($this->sort_column => $this->sort_order);
+      // Use id as a tie breaker
+      if ($this->sort_column != "id") {
+        $orderby["id"] = "ASC";
+      }
     }
     return parent::children($limit, $offset, $where, $orderby);
   }
@@ -569,6 +608,10 @@ class Item_Model extends ORM_MPTT {
   function descendants($limit=null, $offset=0, $where=array(), $orderby=null) {
     if (empty($orderby)) {
       $orderby = array($this->sort_column => $this->sort_order);
+      // Use id as a tie breaker
+      if ($this->sort_column != "id") {
+        $orderby["id"] = "ASC";
+      }
     }
     return parent::descendants($limit, $offset, $where, $orderby);
   }