Continuing [r4488] N.536 Regression introduced in [r4469] (N.505), itself fixing a regression introduced in [r4404]. REQUIRES TESTING

git-svn-id: http://svn.code.sf.net/p/itop/code/trunk@4490 a333f486-631f-4898-b8df-5754b55c2be0

core/dbobjectsearch.class.php

@@ -1426,7 +1426,10 @@ class DBObjectSearch extends DBSearch
 				}
 			}
 			$sRawId .= $bGetCount;
-			$sRawId .= implode(',', $aSelectedClasses); // Unions may alter the list of selected columns
+			if (is_array($aSelectedClasses))
+			{
+				$sRawId .= implode(',', $aSelectedClasses); // Unions may alter the list of selected columns
+			}
 			$sOqlId = md5($sRawId);
 		}
 		else