[erp_hal_json_style]: count_method should not fail if it is empty or invalid

bt5/erp5_hal_json_style/SkinTemplateItem/portal_skins/erp5_hal_json_style/ERP5Document_getHateoas.py

@@ -1926,16 +1926,29 @@ def calculateHateoas(is_portal=None, is_site_root=None, traversed_document=None,
     if source_field is not None and source_field_meta_type == "ListBox":
       # Trigger count method if exist
       # XXX No need to count if no pagination
-      count_method = source_field.get_value('count_method')
-      if count_method != "" and count_method.getMethodName() != list_method:
+      count_method = source_field.get_value('count_method') or None
+      count_method_name = count_method.getMethodName() if count_method is not None else ""
+
+      # Only try to get count method results in case method name exists, in all
+      # other cases, just pass.
+      if count_method_name != "" and count_method_name != list_method:
         count_kw = dict(catalog_kw)
         # Drop not needed parameters
         count_kw.pop('selection', None)
         count_kw.pop('selection_name', None)
         count_kw.pop("sort_on", None)
         count_kw.pop("limit", None)
-        count_method_result = getattr(traversed_document, count_method.getMethodName())(REQUEST=REQUEST, **count_kw)
+        try:
+          count_method = getattr(traversed_document, count_method_name)
+          count_method_result = count_method(REQUEST=REQUEST, **count_kw)
           result_dict['_embedded']['count'] = ensureSerializable(count_method_result[0][0])
+        except AttributeError as error:
+          # In case there is no count_method or some invalid mehtod, instead of
+          # raising error and breaking the view, its better to log on as warning
+          # and just pass. This also ensures we have compatibilty with how old
+          # UI behave in these cases.
+          log('Invalid count method %s' % error, level=800)
+          pass
 
       contents_stat_list = []
       # in case the search was issued by listbox we can provide results of