Domain basetypes aren't loaded as encoders/decoders to the client cache

[QuantumTM]

• asyncpg version: 0.22.0 (also tested on 0.25.0)
• PostgreSQL version: 11
• Do you use a PostgreSQL SaaS? If so, which? Can you reproduce
  the issue with a local PostgreSQL install?: N/A
• Python version: 3.8
• Platform: linux
• Do you use pgbouncer?: No
• Did you install asyncpg with pip?: Yes
• If you built asyncpg locally, which version of Cython did you use?: N/A
• Can the issue be reproduced under both asyncio and
  uvloop?: Not tested

When attempting an insert on a domain type I hit an issue where asyncpg was unable to handle the numeric[] type;

Traceback (most recent call last):
  File "test.py", line 40, in <module>
    asyncio.run(main())
  File "/usr/local/lib/python3.8/asyncio/runners.py", line 43, in run
    return loop.run_until_complete(main)
  File "/usr/local/lib/python3.8/asyncio/base_events.py", line 616, in run_until_complete
    return future.result()
  File "test.py", line 36, in main
    await insert_num_array(conn, [1, 2])
  File "test.py", line 29, in insert_num_array
    await conn.execute(sql, (num_array,))
  File "/home/quantumtm/src/asyncpg/asyncpg/connection.py", line 320, in execute
    _, status, _ = await self._execute(
  File "/home/quantumtm/src/asyncpg/asyncpg/connection.py", line 1659, in _execute
    result, _ = await self.__execute(
  File "/home/quantumtm/src/asyncpg/asyncpg/connection.py", line 1684, in __execute
    return await self._do_execute(
  File "/home/quantumtm/src/asyncpg/asyncpg/connection.py", line 1711, in _do_execute
    stmt = await self._get_statement(
  File "/home/quantumtm/src/asyncpg/asyncpg/connection.py", line 416, in _get_statement
    settings.register_data_types(types)
  File "asyncpg/protocol/settings.pyx", line 35, in asyncpg.protocol.protocol.ConnectionSettings.register_data_types
    cpdef inline register_data_types(self, types):
  File "asyncpg/protocol/settings.pyx", line 36, in asyncpg.protocol.protocol.ConnectionSettings.register_data_types
    self._data_codecs.add_types(types)
  File "asyncpg/protocol/codecs/base.pyx", line 556, in asyncpg.protocol.protocol.DataCodecConfig.add_types
    elem_codec = self.declare_fallback_codec(
  File "asyncpg/protocol/codecs/base.pyx", line 706, in asyncpg.protocol.protocol.DataCodecConfig.declare_fallback_codec
    raise exceptions.UnsupportedClientFeatureError(
asyncpg.exceptions._base.UnsupportedClientFeatureError: unhandled standard data type 'numeric[]' (OID 1231)

On analysis this error can occure for any, none str, array type.

A minimal replication case is given below

import asyncio
import asyncpg
from asyncpg.connection import Connection

async def connect():
    return await asyncpg.connect(user="quantumtm", password="quantumtm", database="test", host="127.0.0.1")

async def setup(conn: Connection):
    sql = """
    DROP TABLE IF EXISTS test;
    DROP DOMAIN IF EXISTS num_array;
    CREATE DOMAIN num_array numeric[];
    CREATE TABLE test (
        num num_array
    );
    """
    await conn.execute(sql)

async def insert_num_array(conn: Connection, num_array):
    sql = "INSERT INTO test (num) VALUES ($1)"
    await conn.execute(sql, (num_array,))

async def main():
    conn = await connect()
    await setup(conn)
    await insert_num_array(conn, [1, 2])

if __name__ == '__main__':
    asyncio.run(main())

[QuantumTM]

I've created a pull request #887 which fixes the issue.

In the interim, if other hit this issue, casting to the base type in the sql forces asynpg to load the missing encoders/decoders which fixes the issue. eg/. changing the above insert sql to INSERT INTO test (num) VALUES ($1::numeric[]) avoids the issue.

[QuantumTM]

@elprans with #887 being merged I would concider this issue fix. Would you like me to close the ticket?

[elprans]

Yes. Closing.