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Re: Using a psycopg2 converter to retrieve bytea data from PostgreSQL

From: Daniele Varrazzo <daniele(dot)varrazzo(at)gmail(dot)com>
To: Andy Casey <andycasey(at)gmail(dot)com>
Cc: psycopg(at)postgresql(dot)org
Subject: Re: Using a psycopg2 converter to retrieve bytea data from PostgreSQL
Date: 2012-05-10 21:43:22
Message-ID: CA+mi_8ZaS190SEcNcNW6piVEN-3jY+8EPyd_kHDTwA8xSxxOHA@mail.gmail.com (view raw or flat)
Thread:
Lists: psycopg
On May 10, 2012 11:18 PM, "Andy Casey" <andycasey(at)gmail(dot)com> wrote:
>
> Hi there,
>
> I have used psycopg2's adapters and converters in the past with numeric[]
arrays in PostgreSQL, and now I'm trying to use them with binary data types
(bytea). I've outlined my problem in detail with some test code which
illustrates what works (without adapters/converters), and how it fails when
I build my working code into using an adapter and converter:
>
>
http://stackoverflow.com/questions/10529351/using-a-psycopg2-converter-to-retrieve-bytea-data-from-postgresql
>
> Would you mind taking a look and providing some advice?
>
> Thanks,
> Andy

As answered on SO:

"""
The format you see in the debugger is easy to parse: it is PostgreSQL hex
binary format (
http://www.postgresql.org/docs/9.1/static/datatype-binary.html). psycopg
can parse that format and return a buffer containing the data; you can use
that buffer to obtain an array. Instead of writing a typecaster from
scratch, write one invoking the original func and postprocess its result.
Sorry but I can't remember its name now and I'm writing from a mobile: you
may get further help from the mailing list.
"""

I think you are close to the solution of your case: please keep us informed!

-- Daniele

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