Add '--sort-ascending', '--sort-descending' parameters

Allow users to reverse sorting direction.

Change-Id: Iecd539139c5a7ce4abaaee2ff5632a2459437d51
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>

cliff/lister.py

@@ -10,17 +10,16 @@
 #  License for the specific language governing permissions and limitations
 #  under the License.
 
-"""Application base class for providing a list of data as output.
-"""
+"""Application base class for providing a list of data as output."""
+
 import abc
 import logging
 
 from . import display
 
 
 class Lister(display.DisplayCommandBase, metaclass=abc.ABCMeta):
-    """Command base class for providing a list of data as output.
-    """
+    """Command base class for providing a list of data as output."""
 
     log = logging.getLogger(__name__)
 
@@ -37,13 +36,16 @@ def need_sort_by_cliff(self):
         """Whether sort procedure is performed by cliff itself.
 
         Should be overridden (return False) when there is a need to implement
-        custom sorting procedure or data is already sorted."""
+        custom sorting procedure or data is already sorted.
+        """
         return True
 
     @abc.abstractmethod
     def take_action(self, parsed_args):
-        """Return a tuple containing the column names and an iterable
-        containing the data to be listed.
+        """Run command.
+
+        Return a tuple containing the column names and an iterable containing
+        the data to be listed.
         """
 
     def get_parser(self, prog_name):
@@ -55,16 +57,36 @@ def get_parser(self, prog_name):
             default=[],
             dest='sort_columns',
             metavar='SORT_COLUMN',
-            help=("specify the column(s) to sort the data (columns specified "
-                  "first have a priority, non-existing columns are ignored), "
-                  "can be repeated")
+            help=(
+                'specify the column(s) to sort the data (columns specified '
+                'first have a priority, non-existing columns are ignored), '
+                'can be repeated'
+            ),
+        )
+        sort_dir_group = group.add_mutually_exclusive_group()
+        sort_dir_group.add_argument(
+            '--sort-ascending',
+            action='store_const',
+            dest='sort_direction',
+            const='asc',
+            help=('sort the column(s) in ascending order'),
+        )
+        sort_dir_group.add_argument(
+            '--sort-descending',
+            action='store_const',
+            dest='sort_direction',
+            const='desc',
+            help=('sort the column(s) in descending order'),
         )
         return parser
 
     def produce_output(self, parsed_args, column_names, data):
         if parsed_args.sort_columns and self.need_sort_by_cliff:
-            indexes = [column_names.index(c) for c in parsed_args.sort_columns
-                       if c in column_names]
+            indexes = [
+                column_names.index(c) for c in parsed_args.sort_columns
+                if c in column_names
+            ]
+            reverse = parsed_args.sort_direction == 'desc'
             for index in indexes[::-1]:
                 try:
                     # We need to handle unset values (i.e. None) so we sort on
@@ -76,6 +98,7 @@ def produce_output(self, parsed_args, column_names, data):
                     # the same, i.e. both None or both not-None
                     data = sorted(
                         data, key=lambda k: (k[index] is None, k[index]),
+                        reverse=reverse,
                     )
                 except TypeError:
                     # Simply log and then ignore this; sorting is best effort
@@ -84,18 +107,20 @@ def produce_output(self, parsed_args, column_names, data):
                         parsed_args.sort_columns[index],
                     )
 
-        (columns_to_include, selector) = self._generate_columns_and_selector(
-            parsed_args, column_names)
+        columns_to_include, selector = self._generate_columns_and_selector(
+            parsed_args, column_names,
+        )
         if selector:
             # Generator expression to only return the parts of a row
             # of data that the user has expressed interest in
             # seeing. We have to convert the compress() output to a
             # list so the table formatter can ask for its length.
-            data = (list(self._compress_iterable(row, selector))
-                    for row in data)
-        self.formatter.emit_list(columns_to_include,
-                                 data,
-                                 self.app.stdout,
-                                 parsed_args,
-                                 )
+            data = (
+                list(self._compress_iterable(row, selector)) for row in data
+            )
+
+        self.formatter.emit_list(
+            columns_to_include, data, self.app.stdout, parsed_args,
+        )
+
         return 0

cliff/tests/test_lister.py

@@ -106,6 +106,21 @@ def test_sort_by_column_cliff_side_procedure(self):
         data = list(args[1])
         self.assertEqual([['a', 'A'], ['c', 'A'], ['b', 'B']], data)
 
+    def test_sort_by_column_reverse_order(self):
+        test_lister = ExerciseLister(mock.Mock(), [])
+        parsed_args = mock.Mock()
+        parsed_args.columns = ('Col1', 'Col2')
+        parsed_args.formatter = 'test'
+        parsed_args.sort_columns = ['Col2', 'Col1']
+        parsed_args.sort_direction = 'desc'
+
+        test_lister.run(parsed_args)
+
+        f = test_lister._formatter_plugins['test']
+        args = f.args[0]
+        data = list(args[1])
+        self.assertEqual([['b', 'B'], ['c', 'A'], ['a', 'A']], data)
+
     def test_sort_by_column_data_already_sorted(self):
         test_lister = ExerciseListerCustomSort(mock.Mock(), [])
         parsed_args = mock.Mock()

releasenotes/notes/add-Lister-sort-direction-5f34dba3c9743572.yaml

@@ -0,0 +1,21 @@
+---
+features:
+  - |
+    The ``cliff.lister.Lister`` base class now implements ``--sort-ascending``
+    and ``--sort-descending`` options, which can be used to configure the sort
+    direction. For example::
+
+      $ hello-world list-users --sort-column email --sort-descending
+      +----------------+-----------------------------+
+      | Name           | Email                       |
+      +----------------+-----------------------------+
+      | Charles Xavier | therealcharliex@example.com |
+      | Jim Hendrix    | jim@example.com             |
+      | John Doe       | doe.john@example.com        |
+      | Alice Baker    | abaker@example.com          |
+      +----------------+-----------------------------+
+upgrade:
+  - |
+    ``cliff.lister.Lister`` implementations that override the
+    ``need_sort_by_cliff`` property should now consider the
+    ``--sort-ascending`` and ``--sort-descending`` options.