Re: psycopg3 and adaptation choices

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От Vladimir Ryabtsev
Тема Re: psycopg3 and adaptation choices
Дата
Msg-id CAMqTPqkac5xa=+kwKLj8DEr9OdrkJpEzJj4Re8VvKP=JeTdZog@mail.gmail.com
обсуждение исходный текст
Ответ на Re: psycopg3 and adaptation choices  (Federico Di Gregorio <fog@dndg.it>)
Ответы Re: psycopg3 and adaptation choices  (Daniele Varrazzo <daniele.varrazzo@gmail.com>)
Список psycopg
> I wouldn't want to step away from the %s placeholder ...

Thanks for the elaboration, I agree with your argumentation.

> If there is interest we can think about how to make this querying layer
> more accessible (e.g. using a `cur.execute(PgQuery("select $1, $2"), [...])`

It's always good if such customization is accessible. Having said that,
I can't think of a really good example that benefits from that rather than
from standard use, but basically the more possibilities the better.

> In psycopg3 I've made it slightly easier to use by letting
> `SQL.format()` to accept any Python object

Great, thanks!

May I ask you again about using 'unknown' for numbers? Could you recap
all the downsides of this approach?

Vladimir


On Mon, 9 Nov 2020 at 04:05, Federico Di Gregorio <fog@dndg.it> wrote:
On 09/11/20 13:00, Daniele Varrazzo wrote:
> On Mon, 9 Nov 2020 at 06:57, Federico Di Gregorio <fog@dndg.it> wrote:
[snip]
>> IMHO, oid is a bad idea
>> because it has a very specific semantic and the error messages generated
>> by PostgreSQL will be more confusing.
>
> I'm not sure I understand this. At the moment, the oids are something
> that don't really surface to the end-users, who are not required to
> use them explicitly and shouldn't be seen in the error messages. For
> instance the query above might results in a call:
>
>      >>> from psycopg3.oids import builtins
>      >>> builtins["numeric"].oid
>      1700
>
>      >>> res = conn.pgconn.exec_params(b"select '[]'::jsonb -> $1",
> [b"1"], [1700])
>      >>> res.status
>      <ExecStatus.FATAL_ERROR: 7>
>
>      >>> print(res.error_message.decode("utf8"))
>      ERROR:  operator does not exist: jsonb -> numeric
>      LINE 1: select '[]'::jsonb -> $1
>                                ^
>      HINT:  No operator matches the given name and argument types. You
> might need to add explicit type casts.
>
> So the oid is only used internally, in the mapping python type ->
> exec_params() types array, the 1700 shouldn't surface anywhere.
>
> Maybe I'm misunderstanding your concern: can you tell me better?

My fault. I misread and though you wanted to use OID as *the* type to
pass to PostggreSQL for numbers.

federico



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