Malformed array, unexpected '' when execuing a query to select function metadata

[j-bennet]

Minimal repro case (installed psycopg==3.0.10):

import psycopg

query = """
SELECT n.nspname schema_name,
p.proname func_name,
p.proargnames,
COALESCE(proallargtypes::regtype[], proargtypes::regtype[])::text[],
p.proargmodes,
prorettype::regtype::text return_type,
p.prokind = 'a' is_aggregate,
p.prokind = 'w' is_window,
p.proretset is_set_returning,
d.deptype = 'e' is_extension,
pg_get_expr(proargdefaults, 0) AS arg_defaults
FROM pg_catalog.pg_proc p
INNER JOIN pg_catalog.pg_namespace n
ON n.oid = p.pronamespace
LEFT JOIN pg_depend d ON d.objid = p.oid and d.deptype = 'e'
WHERE p.prorettype::regtype != 'trigger'::regtype
ORDER BY 1, 2
"""

if __name__ == "__main__":
    conn = psycopg.connect(
        user='postgres',
        host='localhost',
        password='',
        port=5432,
        dbname='test',
    )
    conn.autocommit = True

    with conn.cursor() as cur:
        cur.execute(query)
        for row in cur:
            print(row)

Exception:

/Users/irinatruong/.pyenv/versions/pgcli/bin/python "/Users/irinatruong/Library/Application Support/JetBrains/PyCharm2021.3/scratches/scratch.py"
Traceback (most recent call last):
  File "/Users/irinatruong/Library/Application Support/JetBrains/PyCharm2021.3/scratches/scratch.py", line 35, in <module>
    for row in cur:
  File "/Users/irinatruong/.pyenv/versions/pgcli/lib/python3.9/site-packages/psycopg/cursor.py", line 641, in __iter__
    row = load(self._pos)
  File "/Users/irinatruong/.pyenv/versions/pgcli/lib/python3.9/site-packages/psycopg/cursor.py", line 638, in load
    return self._tx.load_row(pos, self._make_row)
  File "/Users/irinatruong/.pyenv/versions/pgcli/lib/python3.9/site-packages/psycopg/_transform.py", line 242, in load_row
    record[col] = self._row_loaders[col](val)
  File "/Users/irinatruong/.pyenv/versions/pgcli/lib/python3.9/site-packages/psycopg/types/array.py", line 347, in load
    raise e.DataError(f"malformed array, unexpected '{wat}'")
psycopg.DataError: malformed array, unexpected ''

Process finished with exit code 1

[dvarrazzo]

Thank you!

Minimal repro:

cnn.execute("select '[0:1]={a,b}'::text[]", binary=False).fetchone()

which is a syntax I had never seen. It's a way to express arrays with lower bound != 1 it seems. Fetching it in binary works.

>>> cnn.execute("select '[0:1]={a,b}'::text[]", binary=True).fetchone()
(['a', 'b'],)

The format is described here.

[dvarrazzo]

Fix to be released in psycopg 3.0.11. Thank you for the report!

[dvarrazzo]

@j-bennet Psycopg 3.0.11 has been released. If this error was found in pgcli you may want to update the min version supported.