Additional validation to prevent non-indexable iterables row objects from crashing

Author: anselor

tableformatter.py

@@ -7,7 +7,7 @@
 import itertools
 import re
 import textwrap as textw
-from typing import List, Iterable, Optional, Tuple, Union, Callable
+from typing import List, Iterable, Optional, Tuple, Union, Callable, Sequence
 
 from wcwidth import wcswidth
 
@@ -18,9 +18,10 @@
 except ImportError:
     from typing import Container, Generic, Sized, TypeVar
 
+    T_co = TypeVar('T_co', covariant=True)
     # Python 3.5
     # noinspection PyAbstractClass
-    class Collection(Generic[TypeVar('T_co', covariant=True)], Container, Sized, Iterable):
+    class Collection(Generic[T_co], Container, Sized, Iterable):
         """hack to enable Collection typing"""
         __slots__ = ()
 
@@ -997,13 +998,18 @@ def generate_table(self, entries: Iterable[Union[Iterable, object]], force_trans
                     else:
                         # check if this is a tuple containing a dictionary of decorated values. If so, the row object
                         # is the first element a the decorated values is the second element.
-                        if len(entry) == 2 and isinstance(entry[1], dict):
-                            entry_obj = entry[0]
-                        else:
+                        is_tagged = False
+                        try:
+                            if isinstance(entry, Sequence) and len(entry) == 2 and isinstance(entry[1], dict):
+                                entry_obj = entry[0]
+                                is_tagged = True
+                            else:
+                                entry_obj = entry
+                        except KeyError:
                             entry_obj = entry
                         if self._row_tagger is not None:
                             entry_opts = self._row_tagger(entry_obj)
-                        if len(entry) == 2 and isinstance(entry[1], dict):
+                        if is_tagged:
                             entry_opts.update(entry[1])
 
                 for column_index, attrib_name in enumerate(self._column_attribs):

tests/test_data_types.py

@@ -3,6 +3,8 @@
 Unit testing the variety of data types supported by tableformatter.
 """
 from collections import OrderedDict
+from typing import Iterator
+
 import tableformatter as tf
 
 
@@ -71,6 +73,47 @@ def test_iterable_of_non_iterable_objects():
     assert table == EXPECTED_WITH_HEADERS
 
 
+class NonIndexableRowObject:
+    def __init__(self, field1: int, field2: int, field3: int, field4: int):
+        self.field1 = field1
+        self.field2 = field2
+        self._field3 = field3
+        self.field4 = field4
+
+    @property
+    def field3(self) -> int:
+        return self._field3
+
+    def __getitem__(self, key: str) -> int:
+        if key == 'field1':
+            return self.field1
+        elif key == 'field2':
+            return self.field2
+        elif key == 'field3':
+            return self.field3
+        elif key == 'field4':
+            return self.field4
+        else:
+            raise KeyError('not a valid field')
+
+    def __len__(self) -> int:
+        return 2
+
+    def __iter__(self) -> Iterator[int]:
+        return iter((self.field1, self.field2, self._field3, self.field4))
+
+
+def test_iterable_of_non_indexable_iterables():
+    rows = [NonIndexableRowObject(1, 2, 3, 4),
+            NonIndexableRowObject(5, 6, 7, 8)]
+    columns = (tf.Column('col1', attrib='field1'),
+               tf.Column('col2', attrib='field2'),
+               tf.Column('col3', attrib='field3'),
+               tf.Column('col4', attrib='field4'))
+    table = tf.generate_table(rows, columns)
+    assert table == EXPECTED_WITH_HEADERS
+
+
 try:
     import numpy as np
 except ImportError: