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Date: Tue, 9 Mar 2021 11:45:30 +0100
From: Hans Ginzel <hans@matfyz.cz>
To: psycopg@postgresql.org
Subject: connect using env. variables
Message-ID: <20210309104530.GN11758@artax.karlin.mff.cuni.cz>
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Please, there should be a possibility to call connect() without parameters
for connecting using environment variables (PGSERVICE, PGDATABASE,…)
or defaults ($USER@localhost/postgres).

Even pg uri postgres:// is valid,
https://www.postgresql.org/docs/current/libpq-connect.html.

>>> d = psycopg2.connect(**parse_dsn('postgres://'))
Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
   File "/usr/lib/python3/dist-packages/psycopg2/__init__.py", line 124, in connect
     raise TypeError('missing dsn and no parameters')
TypeError: missing dsn and no parameters
>>> d = psycopg2.connect(**parse_dsn(''))
Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
   File "/usr/lib/python3/dist-packages/psycopg2/__init__.py", line 124, in connect
     raise TypeError('missing dsn and no parameters')
TypeError: missing dsn and no parameters
>>> db = psycopg2.connect()
Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
   File "/usr/lib/python3/dist-packages/psycopg2/__init__.py", line 124, in connect
     raise TypeError('missing dsn and no parameters')
TypeError: missing dsn and no parameters

Thank you in advance,
Hans