Support NULL in collection deserializer

Author: aboudreault

CHANGELOG.rst

@@ -10,6 +10,7 @@ Features
 * Add additional_write_policy and read_repair to system schema parsing (PYTHON-1048)
 * Remove *read_repair_chance* table options (PYTHON-1140)
 * [GRAPH] Ability to execute Fluent Graph queries asynchronously (PYTHON-1129)
+* Support NULL in collection deserializer (PYTHON-1123)
 
 Bug Fixes
 ---------

cassandra/cqltypes.py

@@ -813,9 +813,12 @@ def deserialize_safe(cls, byts, protocol_version):
         for _ in range(numelements):
             itemlen = unpack(byts[p:p + length])
             p += length
-            item = byts[p:p + itemlen]
-            p += itemlen
-            result.append(subtype.from_binary(item, inner_proto))
+            if itemlen < 0:
+                result.append(None)
+            else:
+                item = byts[p:p + itemlen]
+                p += itemlen
+                result.append(subtype.from_binary(item, inner_proto))
         return cls.adapter(result)
 
     @classmethod
@@ -867,14 +870,23 @@ def deserialize_safe(cls, byts, protocol_version):
         for _ in range(numelements):
             key_len = unpack(byts[p:p + length])
             p += length
-            keybytes = byts[p:p + key_len]
-            p += key_len
+            if key_len < 0:
+                keybytes = None
+                key = None
+            else:
+                keybytes = byts[p:p + key_len]
+                p += key_len
+                key = key_type.from_binary(keybytes, inner_proto)
+
             val_len = unpack(byts[p:p + length])
             p += length
-            valbytes = byts[p:p + val_len]
-            p += val_len
-            key = key_type.from_binary(keybytes, inner_proto)
-            val = value_type.from_binary(valbytes, inner_proto)
+            if val_len < 0:
+                val = None
+            else:
+                valbytes = byts[p:p + val_len]
+                p += val_len
+                val = value_type.from_binary(valbytes, inner_proto)
+
             themap._insert_unchecked(key, keybytes, val)
         return themap
 

tests/unit/test_types.py

@@ -29,7 +29,8 @@
     CassandraType, DateRangeType, DateType, DecimalType,
     EmptyValue, LongType, SetType, UTF8Type,
     cql_typename, int8_pack, int64_pack, lookup_casstype,
-    lookup_casstype_simple, parse_casstype_args
+    lookup_casstype_simple, parse_casstype_args,
+    int32_pack, Int32Type, ListType, MapType
 )
 from cassandra.encoder import cql_quote
 from cassandra.pool import Host
@@ -226,6 +227,46 @@ def test_datetype(self):
         expected = 2177403010.123
         self.assertEqual(DateType.deserialize(int64_pack(int(1000 * expected)), 0), datetime.datetime(2038, 12, 31, 10, 10, 10, 123000))
 
+    def test_collection_null_support(self):
+        """
+        Test that null values in collection are decoded properly.
+
+        @jira_ticket PYTHON-1123
+        """
+        int_list = ListType.apply_parameters([Int32Type])
+        value = (
+                int32_pack(2) +  # num items
+                int32_pack(-1) +  # size of item1
+                int32_pack(4) +  # size of item2
+                int32_pack(42)  # item2
+        )
+        self.assertEqual(
+            [None, 42],
+            int_list.deserialize(value, 3)
+        )
+
+        set_list = SetType.apply_parameters([Int32Type])
+        self.assertEqual(
+            {None, 42},
+            set(set_list.deserialize(value, 3))
+        )
+
+        value = (
+                int32_pack(2) +  # num items
+                int32_pack(4) +  # key size of item1
+                int32_pack(42) +  # key item1
+                int32_pack(-1) +  # value size of item1
+                int32_pack(-1) +  # key size of item2
+                int32_pack(4) +  # value size of item2
+                int32_pack(42)  # value of item2
+        )
+
+        map_list = MapType.apply_parameters([Int32Type, Int32Type])
+        self.assertEqual(
+            [(42, None), (None, 42)],
+            map_list.deserialize(value, 3)._items  # OrderedMapSerializedKey
+        )
+
     def test_write_read_string(self):
         with tempfile.TemporaryFile() as f:
             value = u'test'