Unable to set Codec to Custom Type (pguint)

• asyncpg version: 0.20.0
• PostgreSQL version: 12.2
• Do you use a PostgreSQL SaaS? If so, which? Can you reproduce
  the issue with a local PostgreSQL install?: No, N/A, N/A
• Python version: 3.8.0
• Platform: Linux 64bit (Ubuntu 18.04)
• 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?: That's actually what I'm using.

I am using the user extension pguint (there's a pg11&12 branch) and it's installed fine. I'm trying to load ~100GB of article data onto my database, so I'm using the binary copy functions.

I created a binary encoder and decoder:

await con.set_type_codec( 'uint1', encoder=lambda x: struct.pack('!B',x), decoder=lambda x: struct.unpack('!B',x), format='binary')

But when I try to use it, I get:

Caught Insert Error.  UID:2419 EX: no binary input function available for type uint1

as my error. I tried delving into the source of this project but wasn't able to glean much. Does this error mean that the postgres extension itself is missing the required function on its end?

As a side note: I wrote a correct encoder/decoder (both text and binary) for the tsvector type, I want to submit a pull request but have no idea where I should put the new code, want to point me in the right direction?

also, should I be including the postgres varlena header in my binary encoding function outputs? or does your code do that?

Inizia con set_type_codec e le funzioni COPY binarie descritte nel report, riproducendo il malfunzionamento di uint1 con PostgreSQL 12.2, asyncpg 0.20.0, Python 3.8 e uvloop. Verifica il comportamento dell’input binario di pguint e la questione relativa agli header varlena. Il lavoro è terminato quando sono state stabilite la causa e le indicazioni supportate, incluso dove dovrebbe essere collocato un contributo per un codec tsvector.