Fixed __unicode__/__str__ for dataset with no headers

tablib/core.py

@@ -223,7 +223,8 @@ class Dataset(object):
         result = []
 
         # Add unicode representation of headers.
-        result.append([unicode(h) for h in self.__headers])
+        if self.__headers:
+            result.append([unicode(h) for h in self.__headers])
 
         # Add unicode representation of rows.
         result.extend(list(map(unicode, row)) for row in self._data)
@@ -232,7 +233,8 @@ class Dataset(object):
         field_lens = list(map(max, zip(*lens)))
 
         # delimiter between header and data
-        result.insert(1, ['-' * length for length in field_lens])
+        if self.__headers:
+            result.insert(1, ['-' * length for length in field_lens])
 
         format_string = '|'.join('{%s:%s}' % item for item in enumerate(field_lens))
 

test_tablib.py

@@ -351,6 +351,16 @@ class TablibTestCase(unittest.TestCase):
         self.assertFalse('^' in output)
         self.assertTrue('textasciicircum' in output)
 
+    def test_str_no_columns(self):
+        d = tablib.Dataset(['a', 1], ['b', 2], ['c', 3])
+        output = '%s' % d
+
+        self.assertEqual(output.splitlines(), [
+            'a|1',
+            'b|2',
+            'c|3'
+        ])
+
     def test_unicode_append(self):
         """Passes in a single unicode character and exports."""