[PYTHON-1121] Fix queryset generation for cqlengine Token instances

Author: TheRealFalcon

CHANGELOG.rst

@@ -98,6 +98,7 @@ Bug Fixes
 * Call ConnectionException with correct kwargs (PYTHON-1117)
 * Can't connect to clusters built from source because version parsing doesn't handle 'x.y-SNAPSHOT' (PYTHON-1118)
 * Discovered node doesn´t honor the configured Cluster port on connection (PYTHON-1127)
+* Exception when use pk__token__gt filter In python 3.7 (PYTHON-1121)
 
 Other
 -----

cassandra/cqlengine/columns.py

@@ -1071,7 +1071,7 @@ class _PartitionKeysToken(Column):
     """
 
     def __init__(self, model):
-        self.partition_columns = model._partition_keys.values()
+        self.partition_columns = list(model._partition_keys.values())
         super(_PartitionKeysToken, self).__init__(partition_key=True)
 
     @property

tests/integration/cqlengine/query/test_queryoperators.py

@@ -94,6 +94,7 @@ def test_token_function(self):
         # pk__token equality
         r = TokenTestModel.objects(pk__token=functions.Token(last_token))
         self.assertEqual(len(r), 1)
+        r.all()  # Attempt to obtain queryset for results. This has thrown an exception in the past
 
     def test_compound_pk_token_function(self):