Be more accepting with None value in headers candidate (#331)

We already filter out a line will only None values, and sometimes
Excel of LibreOffice mistakes the real number of columns adding
one or more that have no value at all.

sandbox/grist/imports/import_utils.py

@@ -52,7 +52,7 @@ def _is_numeric(text):
     try:
       t(text)
       return True
-    except (ValueError, OverflowError):
+    except (ValueError, OverflowError, TypeError):
       pass
   return False
 
@@ -63,7 +63,7 @@ def _is_header(header, data_rows):
   """
   # See if the row has any non-text values.
   for cell in header:
-    if not isinstance(cell, six.string_types) or _is_numeric(cell):
+    if not (isinstance(cell, six.string_types) or cell is None) or _is_numeric(cell):
       return False
 
 
@@ -109,7 +109,7 @@ def expand_headers(headers, data_offset, rows):
   row_length = max(itertools.chain([len(headers)],
                                    (_count_nonempty(r) for r in itertools.islice(rows, data_offset,
                                                                                  None))))
-  header_values = [h.strip() for h in headers] + [u''] * (row_length - len(headers))
+  header_values = [h.strip() if h else '' for h in headers] + [u''] * (row_length - len(headers))
   return header_values
 
 

sandbox/grist/imports/import_xls_test.py

@@ -105,17 +105,17 @@ class TestImportXLS(unittest.TestCase):
       'table_name': u'Transaction Report',
       'column_metadata': [
         {'type': 'Any', 'id': u''},
-        {'type': 'Any', 'id': u''},
+        {'type': 'Numeric', 'id': u'Start'},
         {'type': 'Numeric', 'id': u''},
         {'type': 'Numeric', 'id': u''},
-        {'type': 'Any', 'id': u''},
+        {'type': 'Any', 'id': u'Seek no easy ways'},
       ],
       'table_data': [
-        ['', u'SINGLE MERGED', u'The End'],
-        ['Start', '1637384.52', ''],
-        [None, 2444344.06, None],
-        [None, 2444344.06, None],
-        ['Seek no easy ways', u'', u''],
+        [u'SINGLE MERGED', u'The End'],
+        [1637384.52, None],
+        [2444344.06, None],
+        [2444344.06, None],
+        [u'', u''],
       ],
     }])
 
@@ -225,6 +225,25 @@ class TestImportXLS(unittest.TestCase):
       ],
     }])
 
+  def test_header_with_none_cell(self):
+    parsed_file = import_xls.parse_file(*_get_fixture('test_headers_with_none_cell.xlsx'))
+    tables = parsed_file[1]
+    self.assertEqual(tables, [{
+      'table_name': 'Sheet1',
+      'column_metadata': [
+        {'id': u'header1', 'type': 'Any'},
+        {'id': u'header2', 'type': 'Any'},
+        {'id': u'header3', 'type': 'Any'},
+        {'id': u'header4', 'type': 'Any'},
+      ],
+      'table_data': [
+        ['foo1', 'foo2'],
+        ['bar1', 'bar2'],
+        ['baz1', 'baz2'],
+        ['boz1', 'boz2'],
+      ],
+    }])
+
 
 if __name__ == '__main__':
   unittest.main()