Prepared statement

aiomysql/connection.py

@@ -15,7 +15,6 @@
 from pymysql.constants import SERVER_STATUS
 from pymysql.constants import CLIENT
 from pymysql.constants import COMMAND
-from pymysql.constants import FIELD_TYPE
 from pymysql.util import byte2int, int2byte
 from pymysql.converters import (escape_item, encoders, decoders,
                                 escape_string, escape_bytes_prefixed, through)
@@ -25,7 +24,7 @@
                          IntegrityError, InternalError, NotSupportedError,
                          ProgrammingError)
 
-from pymysql.connections import TEXT_TYPES, MAX_PACKET_LEN, DEFAULT_CHARSET
+from pymysql.connections import MAX_PACKET_LEN, DEFAULT_CHARSET
 from pymysql.connections import _auth
 
 from pymysql.connections import pack_int24
@@ -39,8 +38,9 @@
 
 # from aiomysql.utils import _convert_to_str
 from .cursors import Cursor
-from .utils import _ConnectionContextManager, _ContextManager
+from .utils import _ConnectionContextManager, _ContextManager, _decide_encoding
 from .log import logger
+from .prepared_statement import PreparedStatement
 
 DEFAULT_USER = getpass.getuser()
 
@@ -971,6 +971,38 @@ async def sha256_password_auth(self, pkt):
         pkt.check_error()
         return pkt
 
+    async def prepare(self, sql):
+        await self._execute_command(COMMAND.COM_STMT_PREPARE, sql)
+        packet = await self._read_packet()
+        if not packet.is_ok_packet():
+            raise Error("Unexpected error")
+
+        # status
+        packet.advance(1)
+        statement_id = packet.read_uint32()
+        num_columns = packet.read_uint16()
+        num_params = packet.read_uint16()
+        # reserved
+        packet.advance(1)
+        # warning count
+        packet.read_uint16()
+        params = []
+        columns = []
+        if num_params > 0:
+            for _ in range(num_params):
+                params.append(await self._read_packet(FieldDescriptorPacket))
+            if self.client_flag | CLIENT.PROTOCOL_41:
+                # EOF
+                await self._read_packet()
+        if num_columns > 0:
+            for _ in range(num_columns):
+                columns.append(await self._read_packet(FieldDescriptorPacket))
+            if self.client_flag | CLIENT.PROTOCOL_41:
+                # EOF
+                await self._read_packet()
+
+        return PreparedStatement(self, statement_id, params, columns)
+
     # _mysql support
     def thread_id(self):
         return self.server_thread_id[0]
@@ -1244,30 +1276,8 @@ async def _get_descriptions(self):
                 FieldDescriptorPacket)
             self.fields.append(field)
             description.append(field.description())
-            field_type = field.type_code
-            if use_unicode:
-                if field_type == FIELD_TYPE.JSON:
-                    # When SELECT from JSON column: charset = binary
-                    # When SELECT CAST(... AS JSON): charset = connection
-                    # encoding
-                    # This behavior is different from TEXT / BLOB.
-                    # We should decode result by connection encoding
-                    # regardless charsetnr.
-                    # See https://github.com/PyMySQL/PyMySQL/issues/488
-                    encoding = conn_encoding  # SELECT CAST(... AS JSON)
-                elif field_type in TEXT_TYPES:
-                    if field.charsetnr == 63:  # binary
-                        # TEXTs with charset=binary means BINARY types.
-                        encoding = None
-                    else:
-                        encoding = conn_encoding
-                else:
-                    # Integers, Dates and Times, and other basic data
-                    # is encoded in ascii
-                    encoding = 'ascii'
-            else:
-                encoding = None
-            converter = self.connection.decoders.get(field_type)
+            encoding = _decide_encoding(use_unicode, conn_encoding, field)
+            converter = self.connection.decoders.get(field.type_code)
             if converter is through:
                 converter = None
             self.converters.append((encoding, converter))

aiomysql/cursors.py

@@ -3,13 +3,13 @@
 import warnings
 import contextlib
 
+from pymysql.constants import FIELD_TYPE
 from pymysql.err import (
     Warning, Error, InterfaceError, DataError,
     DatabaseError, OperationalError, IntegrityError, InternalError,
     NotSupportedError, ProgrammingError)
 
 from .log import logger
-from .connection import FIELD_TYPE
 
 # https://github.com/PyMySQL/PyMySQL/blob/master/pymysql/cursors.py#L11-L18