cinder list now prints dash '-' when data is None

cinder list used to print None when volume was created without name.
Now it prints '-' dash when display_name is None

Closes-Bug: #1422244
Change-Id: I195ccc37fe96dbb54a0460527fabf55146170bc7

cinderclient/tests/test_utils.py

@@ -121,6 +121,21 @@ class PrintListTestCase(test_utils.TestCase):
 | 1 | 2 |
 | 3 | 4 |
 +---+---+
+""", cso.read())
+
+    def test_print_list_with_None_data(self):
+        Row = collections.namedtuple('Row', ['a', 'b'])
+        to_print = [Row(a=3, b=None), Row(a=1, b=2)]
+        with CaptureStdout() as cso:
+            utils.print_list(to_print, ['a', 'b'])
+        # Output should be sorted by the first key (a)
+        self.assertEqual("""\
++---+---+
+| a | b |
++---+---+
+| 1 | 2 |
+| 3 | - |
++---+---+
 """, cso.read())
 
     def test_print_list_with_list_sortby(self):

cinderclient/utils.py

@@ -139,6 +139,8 @@ def print_list(objs, fields, formatters=None, sortby_index=0):
                     data = o[field]
                 else:
                     data = getattr(o, field_name, '')
+                if data is None:
+                    data = '-'
                 row.append(data)
         pt.add_row(row)