Fix sort of *list command output

While sorting output of list command ("audittemplate list",
"strategy list", etc)  by sort-key that is not belongs
to specific model, this sort-key was passed to db what
caused error (HTTP 500). We added check on such keys and now,
if got one of them, then we make sort on API side
instead of db side.

We removed excess sort and changed all sorting routines
to unified way.

Also added sort tests on every model.

Change-Id: I41faea1622605ee4fa8dc48cd572876d75be8383
Closes-Bug: 1662887

watcher/api/controllers/v1/utils.py

@@ -13,6 +13,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from operator import attrgetter
+
 import jsonpatch
 from oslo_config import cfg
 from oslo_utils import reflection
@@ -54,6 +56,13 @@ def validate_sort_dir(sort_dir):
                                          "'asc' or 'desc'") % sort_dir)
 
 
+def validate_sort_key(sort_key, allowed_fields):
+    # Very lightweight validation for now
+    if sort_key not in allowed_fields:
+        raise wsme.exc.ClientSideError(
+            _("Invalid sort key: %s") % sort_key)
+
+
 def validate_search_filters(filters, allowed_fields):
     # Very lightweight validation for now
     # todo: improve this (e.g. https://www.parse.com/docs/rest/guide/#queries)
@@ -63,6 +72,19 @@ def validate_search_filters(filters, allowed_fields):
                 _("Invalid filter: %s") % filter_name)
 
 
+def check_need_api_sort(sort_key, additional_fields):
+    return sort_key in additional_fields
+
+
+def make_api_sort(sorting_list, sort_key, sort_dir):
+    # First sort by uuid field, than sort by sort_key
+    # sort() ensures stable sorting, so we could
+    # make lexicographical sort
+    reverse_direction = (sort_dir == 'desc')
+    sorting_list.sort(key=attrgetter('uuid'), reverse=reverse_direction)
+    sorting_list.sort(key=attrgetter(sort_key), reverse=reverse_direction)
+
+
 def apply_jsonpatch(doc, patch):
     for p in patch:
         if p['op'] == 'add' and p['path'].count('/') == 1: