Expose result_keys on PageIterator object

This was expose on the Paginator object, but also needs to be
exposed through the PageIterator object.

Fixes #442.

botocore/paginate.py

@@ -105,18 +105,22 @@ def _extract_paging_params(self, kwargs):
 
 class PageIterator(object):
     def __init__(self, operation, input_token, output_token, more_results,
-                 result_key, max_items, starting_token, endpoint, op_kwargs):
+                 result_keys, max_items, starting_token, endpoint, op_kwargs):
         self._operation = operation
         self._input_token = input_token
         self._output_token = output_token
         self._more_results = more_results
-        self._result_key = result_key
+        self._result_keys = result_keys
         self._max_items = max_items
         self._starting_token = starting_token
         self._endpoint = endpoint
         self._op_kwargs = op_kwargs
         self._resume_token = None
 
+    @property
+    def result_keys(self):
+        return self._result_keys
+
     @property
     def resume_token(self):
         """Token to specify to resume pagination."""
@@ -135,7 +139,7 @@ def __iter__(self):
         # The number of items from result_key we've seen so far.
         total_items = 0
         first_request = True
-        primary_result_key = self._result_key[0]
+        primary_result_key = self.result_keys[0]
         starting_truncation = 0
         self._inject_starting_token(current_kwargs)
         while True:
@@ -205,7 +209,7 @@ def _handle_first_request(self, parsed, primary_result_key,
         # We also need to truncate any secondary result keys
         # because they were not truncated in the previous last
         # response.
-        for token in self._result_key:
+        for token in self.result_keys:
             if token == primary_result_key:
                 continue
             parsed[token] = []
@@ -241,9 +245,9 @@ def _get_next_token(self, parsed):
         return next_tokens
 
     def result_key_iters(self):
-        teed_results = tee(self, len(self._result_key))
+        teed_results = tee(self, len(self.result_keys))
         return [ResultKeyIterator(i, result_key) for i, result_key
-                in zip(teed_results, self._result_key)]
+                in zip(teed_results, self.result_keys)]
 
     def build_full_result(self):
         iterators = self.result_key_iters()

tests/unit/test_paginate.py

@@ -514,6 +514,13 @@ def test_resume_with_multiple_input_keys(self):
             self.operation.call.call_args_list,
             [mock.call(None, InMarker1='m1', InMarker2='m2'),])
 
+    def test_result_key_exposed_on_paginator(self):
+        self.assertEqual(self.paginator.result_keys, ['Users', 'Groups'])
+
+    def test_result_key_exposed_on_page_iterator(self):
+        pages = self.paginator.paginate(None, max_items=3)
+        self.assertEqual(pages.result_keys, ['Users', 'Groups'])
+
 
 if __name__ == '__main__':
     unittest.main()