Adjust handling of XMLType to manage the case when embedded LOBs are

used instead of direct strings.

Author: anthony-tuininga

src/oracledb/errors.py

@@ -227,6 +227,7 @@ def _raise_from_string(exc_type: Exception, message: str) -> None:
 ERR_UNEXPECTED_DATA = 5004
 ERR_UNEXPECTED_REFUSE = 5005
 ERR_UNEXPECTED_END_OF_DATA = 5006
+ERR_UNEXPECTED_XML_TYPE = 5007
 
 # error numbers that result in OperationalError
 ERR_LISTENER_REFUSED_CONNECTION = 6000
@@ -476,6 +477,8 @@ def _raise_from_string(exc_type: Exception, message: str) -> None:
     ERR_UNEXPECTED_REFUSE:
             'the listener refused the connection but an unexpected error '
             'format was returned',
+    ERR_UNEXPECTED_XML_TYPE:
+            'unexpected XMLType with flag {flag}',
     ERR_UNSUPPORTED_INBAND_NOTIFICATION:
             'unsupported in-band notification with error number {err_num}',
     ERR_UNSUPPORTED_PYTHON_TYPE_FOR_DB_TYPE:

src/oracledb/impl/thin/buffer.pyx

@@ -791,14 +791,20 @@ cdef class Buffer:
         cdef const char_type *ptr = self._get_raw(4)
         value[0] = unpack_uint32(ptr, byte_order)
 
-    cdef object read_xmltype(self):
+    cdef object read_xmltype(self, ThinConnImpl conn_impl):
         """
         Reads an XMLType value from the buffer and returns the string value.
         The XMLType object is a special DbObjectType and is handled separately
         since the structure is a bit different.
         """
         cdef:
+            uint8_t image_flags, image_version
+            DbObjectPickleBuffer buf
+            ThinLobImpl lob_impl
+            const char_type *ptr
             uint32_t num_bytes
+            ssize_t bytes_left
+            uint32_t xml_flag
             bytes packed_data
         self.read_ub4(&num_bytes)
         if num_bytes > 0:                   # type OID
@@ -814,7 +820,22 @@ cdef class Buffer:
         self.skip_ub2()                     # flags
         if num_bytes > 0:
             packed_data = self.read_bytes()
-            return packed_data[12:].decode()
+            buf = DbObjectPickleBuffer.__new__(DbObjectPickleBuffer)
+            buf._populate_from_bytes(packed_data)
+            buf.read_header(&image_flags, &image_version)
+            buf.skip_raw_bytes(1)           # XML version
+            buf.read_uint32(&xml_flag)
+            if xml_flag & TNS_XML_TYPE_FLAG_SKIP_NEXT_4:
+                buf.skip_raw_bytes(4)
+            bytes_left = buf.bytes_left()
+            ptr = buf.read_raw_bytes(bytes_left)
+            if xml_flag & TNS_XML_TYPE_STRING:
+                return ptr[:bytes_left].decode()
+            elif xml_flag & TNS_XML_TYPE_LOB:
+                lob_impl = ThinLobImpl._create(conn_impl, DB_TYPE_CLOB,
+                                               ptr[:bytes_left])
+                return PY_TYPE_LOB._from_impl(lob_impl)
+            errors._raise_err(errors.ERR_UNEXPECTED_XML_TYPE, flag=xml_flag)
 
     cdef int skip_raw_bytes(self, ssize_t num_bytes) except -1:
         """

src/oracledb/impl/thin/constants.pxi

@@ -451,6 +451,11 @@ DEF TNS_OBJ_TDS_TYPE_TIMESTAMP_LTZ = 33
 DEF TNS_OBJ_TDS_TYPE_BINARY_FLOAT = 37
 DEF TNS_OBJ_TDS_TYPE_BINARY_DOUBLE = 45
 
+# xml type constants
+DEF TNS_XML_TYPE_LOB = 0x0001
+DEF TNS_XML_TYPE_STRING = 0x0004
+DEF TNS_XML_TYPE_FLAG_SKIP_NEXT_4 = 0x100000
+
 # execute options
 DEF TNS_EXEC_OPTION_PARSE = 0x01
 DEF TNS_EXEC_OPTION_BIND = 0x08

src/oracledb/impl/thin/cursor.pyx

@@ -77,13 +77,20 @@ cdef class ThinCursorImpl(BaseCursorImpl):
         the variable is created to determine if a conversion is required and
         therefore a define must be performed.
         """
-        cdef ThinVarImpl var_impl
+        cdef:
+            ThinDbObjectTypeImpl typ_impl
+            ThinVarImpl var_impl
         BaseCursorImpl._create_fetch_var(self, conn, cursor, type_handler, pos,
                                          fetch_info)
         var_impl = self.fetch_var_impls[pos]
         if var_impl.dbtype._ora_type_num != fetch_info._dbtype._ora_type_num:
             conversion_helper(var_impl, fetch_info,
                               &self._statement._requires_define)
+        elif var_impl.objtype is not None:
+            typ_impl = var_impl.objtype
+            if typ_impl.is_xml_type:
+                var_impl.outconverter = \
+                        lambda v: v if isinstance(v, str) else v.read()
 
     cdef int _fetch_rows(self, object cursor) except -1:
         """

src/oracledb/impl/thin/messages.pyx

@@ -603,7 +603,7 @@ cdef class MessageWithData(Message):
         elif ora_type_num == TNS_DATA_TYPE_INT_NAMED:
             typ_impl = var_impl.objtype
             if typ_impl.is_xml_type:
-                column_value = buf.read_xmltype()
+                column_value = buf.read_xmltype(self.conn_impl)
             else:
                 obj_impl = buf.read_dbobject(typ_impl)
                 if obj_impl is not None: