SQLCatalog: Add function for returning filter_dict

And simplify manage_exportProperties function accordingly

product/ZSQLCatalog/SQLCatalog.py

@@ -672,6 +672,9 @@ class Catalog(Folder,
   def _clearCaches(self):
     self._cache_sequence_number += 1
 
+  def _getFilterDict(self):
+    return self.filter_dict
+
   security.declarePrivate('getSQLCatalogRoleKeysList')
   def getSQLCatalogRoleKeysList(self):
     """
@@ -741,16 +744,9 @@ class Catalog(Folder,
         f.write('  </property>\n')
     # XXX Although filters are not properties, output filters here.
     # XXX Ideally, filters should be properties in Z SQL Methods, shouldn't they?
-    if hasattr(self, 'filter_dict'):
-      filter_list = []
-      for filter_id in self.filter_dict.keys():
-        filter_definition = self.filter_dict[filter_id]
-        filter_list.append((filter_id, filter_definition))
-      # Sort for easy diff
-      filter_list.sort(key=lambda x: x[0])
-      for filter_item in filter_list:
-        filter_id  = filter_item[0]
-        filter_def = filter_item[1]
+    filter_dict = self._getFilterDict()
+    if filter_dict:
+      for filter_id, filter_def in sorted(filter_dict.iteritems()):
         if not filter_def['filtered']:
           # If a filter is not activated, no need to output it.
           continue
@@ -1603,7 +1599,7 @@ class Catalog(Folder,
 
     with (noReadOnlyTransactionCache if disable_cache else
           readOnlyTransactionCache)():
-      filter_dict = self.filter_dict
+      filter_dict = self._getFilterDict()
       catalogged_object_list_cache = {}
       for method_name in method_id_list:
         # We will check if there is an filter on this