On 3/31/20 3:27 PM, Stephen Lagree wrote:
Hello,
I am trying to insert into a table to generate sequential ids. Is there
a way to do this repeatedly using execute_values if there is only one
column and it is auto incremented?
It seems the execute_values requires at least one non-default value.
I am trying to do this:
query = "INSERT INTO MYTABLE (id) VALUES (DEFAULT) RETURNING id;"
execute_values(cursor, query, args_list, template=None,
page_size=100, fetch=True)
If I don't use a %s argument and just put dummy values in the arglist, I
get error
E ValueError: the query doesn't contain any '%s' placeholder
I understand why this doesn't work because it can't extract the
placeholder and replicate values there.
If I change DEFAULT to %s and try to use blank tuples I get this
E psycopg2.errors.SyntaxError: syntax error at or near ")"
E LINE 1: INSERT INTO MYTABLE (id) VALUES (),(),() RETURNING id;
If I use "DEFAULT" as a string it tries to insert a string into an int
column, not use the DEFAULT value. Is there a way to insert the default
value here? I don't see anything like this in the documentation.
My table looks like this:
"CREATE TABLE MYTABLE (id SERIAL PRIMARY KEY)"
A solution from Daniele Varrazzo. I can't find the mailing list post
where it appeared, just where I use it in code:
Given a file:
utilities/psycopg_helpers.py
"""Psycopg2 helper code.
Code for extending psycopg2.
"""
import psycopg2
class Default(object):
"""Set up DEFAULT value for a field.
When doing INSERT or UPDATE in Postgres one can use DEFAULT/default
as the value to have the server use the default set on the field.
The below allows
for doing that.
"""
def __conform__(self, proto):
if proto is psycopg2.extensions.ISQLQuote:
return self
def getquoted(self):
return 'DEFAULT'
DEFAULT = Default()
Then import it:
from .utilities.psycopg_helpers import DEFAULT
and use DEFAULT where you want a SQL DEFAULT.
Thanks,
Steve
--
Adrian Klaver
[email protected]
