[CLIENT-2258] Convert AS_BYTES_PYTHON server type to Python bytearray (…

…#487)

* Docs: data mapping: add headers

doc/data_mapping.rst

@@ -6,9 +6,19 @@ Python Data Mappings
 
 .. rubric:: How Python types map to server types
 
+Default Behavior
+----------------
+
 By default, the :py:class:`~aerospike.Client` maps the supported Python types to Aerospike server \
 `types <https://docs.aerospike.com/server/guide/data-types/overview>`_. \
-When an unsupported type is encountered by the module, it does not serialize the type and will throw an error.
+When an unsupported type is encountered by the module:
+
+1. When sending data to the server, it does not serialize the type and will throw an error.
+2. When reading `AS_BYTES_PYTHON` types from the server, it returns the raw bytes as a :class:`bytearray`.
+   To deserialize this data, the application must use cPickle instead of relying on the client to do it automatically.
+
+Serializers
+-----------
 
 However, the functions :func:`~aerospike.set_serializer` and :func:`~aerospike.set_deserializer` \
 allow for user-defined functions to handle serialization.
@@ -31,6 +41,9 @@ instance-level pair of functions that handle serialization.
 
     All versions before ``6.x`` wrote Python booleans as ``AS_BYTES_PYTHON``.
 
+Data Mappings
+-------------
+
 The following table shows which Python types map directly to Aerospike server types.
 
 +---------------------------------+------------------------+

doc/spelling_wordlist.txt

@@ -3,6 +3,7 @@ lua
 namespace
 geospatial
 serialized
+Serializers
 deserialized
 Aerospike
 aerospike

src/main/serializer.c

@@ -417,10 +417,23 @@ extern as_status deserialize_based_on_as_bytes_type(AerospikeClient *self,
                                                     as_error *error_p)
 {
     switch (as_bytes_get_type(bytes)) {
-    case AS_BYTES_PYTHON:
-        as_error_update(error_p, AEROSPIKE_ERR,
-                        "Unable to deserialize AS_BYTES_PYTHON bytes");
-        break;
+    case AS_BYTES_PYTHON:;
+        // Automatically convert AS_BYTES_PYTHON server types to bytearrays.
+        // This prevents the client from throwing an exception and
+        // breaking applications that don't handle the exception
+        // in case it still fetches AS_BYTES_PYTHON types stored in the server.
+        // Applications using this client must deserialize the bytearrays
+        // manually with cPickle.
+        uint32_t bval_size = as_bytes_size(bytes);
+        PyObject *py_val = PyByteArray_FromStringAndSize(
+            (char *)as_bytes_get(bytes), bval_size);
+        if (!py_val) {
+            as_error_update(error_p, AEROSPIKE_ERR_CLIENT,
+                            "Unable to deserialize AS_BYTES_PYTHON bytes");
+            goto CLEANUP;
+        }
+        *retval = py_val;
+        as_error_update(error_p, AEROSPIKE_OK, NULL);
     case AS_BYTES_BLOB: {
         if (self->user_deserializer_call_info.callback) {
             execute_user_callback(&self->user_deserializer_call_info, &bytes,