Add typed namedtuple Description

aiomysql/_type.py

@@ -0,0 +1,20 @@
+from typing import NamedTuple, Optional
+
+
+class Description(NamedTuple):
+    #: the name of the column returned.
+    name: str
+    #: the type of the column.
+    type_code: int
+    #: the actual length of the column in bytes.
+    display_size: Optional[int]
+    #: the size in bytes of the column associated to this column on the server.
+    internal_size: int
+    #: total number of significant digits in columns of type NUMERIC.
+    #: None for other types.
+    precision: Optional[int]
+    #: count of decimal digits in the fractional part in columns of type NUMERIC.
+    #: None for other types.
+    scale: Optional[int]
+    #: always None as not easy to retrieve from the libpq.
+    null_ok: Optional[bool]

aiomysql/connection.py

@@ -34,6 +34,7 @@
 from pymysql.connections import OKPacketWrapper
 from pymysql.connections import LoadLocalPacketWrapper
 
+from ._type import Description
 # from aiomysql.utils import _convert_to_str
 from .cursors import Cursor
 from .utils import _pack_int24, _lenenc_int, _ConnectionContextManager, _ContextManager
@@ -1317,7 +1318,7 @@ async def _get_descriptions(self):
             field = await self.connection._read_packet(
                 FieldDescriptorPacket)
             self.fields.append(field)
-            description.append(field.description())
+            description.append(Description(*field.description()))
             field_type = field.type_code
             if use_unicode:
                 if field_type == FIELD_TYPE.JSON:

aiomysql/cursors.py

@@ -7,7 +7,9 @@
     Warning, Error, InterfaceError, DataError,
     DatabaseError, OperationalError, IntegrityError, InternalError,
     NotSupportedError, ProgrammingError)
+import typing as t
 
+from ._type import Description
 from .log import logger
 from .connection import FIELD_TYPE
 
@@ -56,23 +58,9 @@ def connection(self):
         return self._connection
 
     @property
-    def description(self):
+    def description(self) -> t.Optional[t.Sequence[Description]]:
         """This read-only attribute is a sequence of 7-item sequences.
 
-        Each of these sequences is a collections.namedtuple containing
-        information describing one result column:
-
-        0.  name: the name of the column returned.
-        1.  type_code: the type of the column.
-        2.  display_size: the actual length of the column in bytes.
-        3.  internal_size: the size in bytes of the column associated to
-            this column on the server.
-        4.  precision: total number of significant digits in columns of
-            type NUMERIC. None for other types.
-        5.  scale: count of decimal digits in the fractional part in
-            columns of type NUMERIC. None for other types.
-        6.  null_ok: always None as not easy to retrieve from the libpq.
-
         This attribute will be None for operations that do not
         return rows or if the cursor has not had an operation invoked
         via the execute() method yet.