Custom Type Conversions issues

[madisvain]

• asyncpg version: 0.11
• PostgreSQL version: 9.5.4_1
• Python version: 3.6
• Platform: Sanic
• Do you use pgbouncer?: No
• Did you install asyncpg with pip?: yes

Trying to overwrite the type conversion:

await connection.set_builtin_type_codec(typename='uuid', schema='pg_catalog', codec_name='char')

ValueError
cannot override codec for type 2950

Traceback (most recent call last):
File /Users/konstruktor/Documents/development/sparkline/env/lib/python3.6/site-packages/sanic/app.py, line 471, in handle_request
response = await response
File /usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/asyncio/coroutines.py, line 109, in __next__
return self.gen.send(None)
File app.py, line 79, in results
await connection.set_builtin_type_codec(typename='uuid', schema='pg_catalog', codec_name='char')
File /usr/local/Cellar/python3/3.6.1/Frameworks/Python.framework/Versions/3.6/lib/python3.6/asyncio/coroutines.py, line 109, in __next__
return self.gen.send(None)
File /Users/konstruktor/Documents/development/sparkline/env/lib/python3.6/site-packages/asyncpg/connection.py, line 806, in set_builtin_type_codec
oid, typename, schema, 'scalar', codec_name)
File asyncpg/protocol/settings.pyx, line 40, in asyncpg.protocol.protocol.ConnectionSettings.set_builtin_type_codec (asyncpg/protocol/protocol.c:5512)
File asyncpg/protocol/settings.pyx, line 42, in asyncpg.protocol.protocol.ConnectionSettings.set_builtin_type_codec (asyncpg/protocol/protocol.c:5390)
File asyncpg/protocol/codecs/base.pyx, line 526, in asyncpg.protocol.protocol.DataCodecConfig.set_builtin_type_codec (asyncpg/protocol/protocol.c:19818)
File asyncpg/protocol/codecs/base.pyx, line 501, in asyncpg.protocol.protocol.DataCodecConfig._set_builtin_type_codec (asyncpg/protocol/protocol.c:19271)

If I use a custom python encoder decoder with uuid type - they are never called.

def uuid_encoder(value):
    return str(1)

def uuid_decoder(value):
    return str(1)

async with app.pool.acquire() as connection:
    #await connection.set_builtin_type_codec(typename='uuid', schema='pg_catalog', codec_name='char')
    await connection.set_type_codec(
        typename='uuid',
        encoder=uuid_encoder,
        decoder=uuid_decoder,
        schema='pg_catalog'
    )
    results = await connection.fetch('SELECT * FROM checks')

[lelit]

Did you try with binary=True? Also, I think a better way is by using the init option to create_pool()... The following works great for me:

async def _setup_connection(con):
    ...
    await con.set_type_codec('jsonb', schema='pg_catalog', binary=True,
                             encoder=_jsonb_encoder, decoder=_jsonb_decoder)

pool = await create_pool(host=host, port=port, ... init=_setup_connection)