Clean the duplicated columns for "nova network-list"

If we specify --fields with default columns name, then there will
be an additional column which is absolutely redundant, we need to
check for such case.

Also do the same for "nova list"

Co-Authored-By: ZhiQiang Fan <aji.zqfan@gmail.com>

Change-Id: Ife0a62d2d77aee261ce39c30d3a89ba97a253dae
Closes-Bug: #1574424

novaclient/tests/unit/v2/test_shell.py

@@ -1082,6 +1082,13 @@ class ShellTest(utils.TestCase):
         self.assertRaises(exceptions.CommandError,
                           self.run_command, 'list --changes-since 0123456789')
 
+    def test_list_fields_redundant(self):
+        output, __ = self.run_command('list --fields id,status,status')
+        header = output.splitlines()[1]
+        self.assertEqual(1, header.count('ID'))
+        self.assertEqual(0, header.count('Id'))
+        self.assertEqual(1, header.count('Status'))
+
     def test_meta_parsing(self):
         meta = ['key1=meta1', 'key2=meta2']
         ref = {'key1': 'meta1', 'key2': 'meta2'}
@@ -2169,6 +2176,13 @@ class ShellTest(utils.TestCase):
                           self.run_command,
                           'network-list --fields vlan,project_id,invalid')
 
+    def test_network_list_redundant_fields(self):
+        output, __ = self.run_command(
+            'network-list --fields label,project_id,project_id')
+        header = output.splitlines()[1]
+        self.assertEqual(1, header.count('Label'))
+        self.assertEqual(1, header.count('Project Id'))
+
     def test_network_show(self):
         self.run_command('network-show 1')
         self.assert_called('GET', '/os-networks')

novaclient/v2/shell.py

@@ -963,24 +963,9 @@ def do_network_list(cs, args):
     """Print a list of available networks."""
     network_list = cs.networks.list()
     columns = ['ID', 'Label', 'Cidr']
-
-    formatters = {}
-    field_titles = []
-    non_existent_fields = []
-    if args.fields:
-        for field in args.fields.split(','):
-            if network_list and not hasattr(network_list[0], field):
-                non_existent_fields.append(field)
-                continue
-            field_title, formatter = utils.make_field_formatter(field, {})
-            field_titles.append(field_title)
-            formatters[field_title] = formatter
-        if non_existent_fields:
-            raise exceptions.CommandError(
-                _("Non-existent fields are specified: %s")
-                % non_existent_fields)
-
-    columns = columns + field_titles
+    columns += _get_list_table_columns_and_formatters(
+        args.fields, network_list,
+        exclude_fields=(c.lower() for c in columns))[0]
     utils.print_list(network_list, columns)
 
 
@@ -1545,28 +1530,17 @@ def do_list(cs, args):
     _translate_extended_states(servers)
 
     formatters = {}
-    field_titles = []
-    non_existent_fields = []
-    if args.fields:
-        for field in args.fields.split(','):
-            if servers and not hasattr(servers[0], field):
-                non_existent_fields.append(field)
-                continue
-            field_title, formatter = utils.make_field_formatter(field,
-                                                                filters)
-            field_titles.append(field_title)
-            formatters[field_title] = formatter
-        if non_existent_fields:
-            raise exceptions.CommandError(
-                _("Non-existent fields are specified: %s")
-                % non_existent_fields)
+
+    cols, fmts = _get_list_table_columns_and_formatters(
+        args.fields, servers, exclude_fields=('id',), filters=filters)
 
     if args.minimal:
         columns = [
             id_col,
             'Name']
-    elif field_titles:
-        columns = [id_col] + field_titles
+    elif cols:
+        columns = [id_col] + cols
+        formatters.update(fmts)
     else:
         columns = [
             id_col,
@@ -1590,6 +1564,71 @@ def do_list(cs, args):
                      formatters, sortby_index=sortby_index)
 
 
+def _get_list_table_columns_and_formatters(fields, objs, exclude_fields=(),
+                                           filters=None):
+    """Check and add fields to output columns.
+
+    If there is any value in fields that not an attribute of obj,
+    CommandError will be raised.
+
+    If fields has duplicate values (case sensitive), we will make them unique
+    and ignore duplicate ones.
+
+    If exclude_fields is specified, any field both in fields and
+    exclude_fields will be ignored.
+
+    :param fields: A list of string contains the fields to be printed.
+    :param objs: An list of object which will be used to check if field is
+                 valid or not. Note, we don't check fields if obj is None or
+                 empty.
+    :param exclude_fields: A tuple of string which contains the fields to be
+                           excluded.
+    :param filters: A dictionary defines how to get value from fields, this
+                    is useful when field's value is a complex object such as
+                    dictionary.
+
+    :return: columns, formatters.
+             columns is a list of string which will be used as table header.
+             formatters is a dictionary specifies how to display the value
+             of the field.
+             They can be [], {}.
+    :raise: novaclient.exceptions.CommandError
+    """
+    if not fields:
+        return [], {}
+
+    if not objs:
+        obj = None
+    elif isinstance(objs, list):
+        obj = objs[0]
+    else:
+        obj = objs
+
+    columns = []
+    formatters = {}
+
+    non_existent_fields = []
+    exclude_fields = set(exclude_fields)
+
+    for field in fields.split(','):
+        if not hasattr(obj, field):
+            non_existent_fields.append(field)
+            continue
+        if field in exclude_fields:
+            continue
+        field_title, formatter = utils.make_field_formatter(field,
+                                                            filters)
+        columns.append(field_title)
+        formatters[field_title] = formatter
+        exclude_fields.add(field)
+
+    if non_existent_fields:
+        raise exceptions.CommandError(
+            _("Non-existent fields are specified: %s") % non_existent_fields)
+
+    return columns, formatters
+
+
 @utils.arg(
     '--hard',
     dest='reboot_type',