fix: preserve dict subclass semantics in bind fast path

Author: mykaul

cassandra/query.py

@@ -608,13 +608,23 @@ def bind(self, values):
         if isinstance(values, dict):
             values_dict = values
             values = []
+            plain_dict = type(values_dict) is dict
 
             # sort values accordingly
             for col in col_meta:
-                val = values_dict.get(col.name, _BIND_SENTINEL)
-                if val is not _BIND_SENTINEL:
-                    values.append(val)
-                elif proto_version >= 4:
+                if plain_dict:
+                    val = values_dict.get(col.name, _BIND_SENTINEL)
+                    if val is not _BIND_SENTINEL:
+                        values.append(val)
+                        continue
+                else:
+                    try:
+                        values.append(values_dict[col.name])
+                        continue
+                    except KeyError:
+                        pass
+
+                if proto_version >= 4:
                     values.append(UNSET_VALUE)
                 else:
                     raise KeyError(

tests/unit/test_parameter_binding.py

@@ -184,6 +184,14 @@ def test_unset_value(self):
         with pytest.raises(ValueError):
             self.bound.bind((0, 0, 0, UNSET_VALUE))
 
+    def test_dict_subclass_missing_value(self):
+        class MissingDict(dict):
+            def __missing__(self, key):
+                return 0
+
+        self.bound.bind(MissingDict({'rk0': 0, 'rk1': 0, 'ck0': 0}))
+        assert self.bound.values == [b'\x00' * 4] * 4
+
 
 class BoundStatementTestV4(BoundStatementTestV3):
     protocol_version = 4
@@ -213,6 +221,14 @@ def test_unset_value(self):
         self.bound.bind((0, 0, 0, UNSET_VALUE))
         assert self.bound.values[-1] == UNSET_VALUE
 
+    def test_dict_subclass_missing_value(self):
+        class MissingDict(dict):
+            def __missing__(self, key):
+                return 0
+
+        self.bound.bind(MissingDict({'rk0': 0, 'rk1': 0, 'ck0': 0}))
+        assert self.bound.values == [b'\x00' * 4] * 4
+
 
 class BoundStatementTestV5(BoundStatementTestV4):
     protocol_version = 5