Re: Problem with memoryview

On Wed, Jul 31, 2013 at 3:08 PM, Frank Millman <frank(at)chagford(dot)com> wrote:
>
> The following refers to Python 3.3.
>
> I know that if you create a column of type 'bytea', psycopg2 accepts a
> variety of inputs, but always returns a 'memoryview'.
>
> I would like to know if it is possible, through some customisation option,
> to tell it to return 'bytes'.

Yes: you can easily create a typecaster converting bytea data to bytes:

def bytea2bytes(value, cur):
m = psycopg2.BINARY(value, cur)
if m is not None:
return m.tobytes()

BYTEA2BYTES = psycopg2.extensions.new_type(
psycopg2.BINARY.values, 'BYTEA2BYTES', bytea2bytes)
psycopg2.extensions.register_type(BYTEA2BYTES)

cur.execute("select 'abcdef'::bytea")
cur.fetchone()[0] # returns b'abcdef'

This would change the behaviour of bytea globally; you can limit the
scope of the change to a single connection or cursor passing this
object as parameter to register_type(): check the function docs for
details.

Hope it helps,

-- Daniele