Trying to get the next value in sequence from a postgres DB, with django

Question

I have a sequence defined in my database that I want to use in my django application. I assumed I could use the raw sql method specified in the django documentation here: http://docs.djangoproject.com/en/1.1/topics/db/sql/. My plan was to execute the following SQL statment:

select nextval('winner')

where winner is the sequence I want to get the next value from. Here is my code:

from django.db import connection, transaction

.....

cursor = connection.cursor()

result = cursor.execute("select nextval('winner')")

The result is always a NoneType object. This seems pretty simple and straightforward, but I haven't been able to make this work. I've tried it in the interactive console with the same results. If I look in the connection.queries object, i see this:

{'time': '0.000', 'sql': "select nextval('winner')"}

The sql generated is valid. Any ideas?

I'm using:

Django 1.1
Python 2.6
Postgres 8.3
Psycopg2
Mac OSX

Feuermurmel · Accepted Answer · 2024-09-05 10:40:02Z

11

This code will work:

from django.db import connection

with connection.cursor() as cursor:
    cursor.execute("select nextval('winner')")
    result = cursor.fetchone()

Full documentation about cursor

edited Sep 5, 2024 at 10:40

Feuermurmel

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answered Apr 27, 2016 at 7:21

Sarath Ak

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Igor Jerosimić · Accepted Answer · 2019-01-09 08:11:17Z

6

cursor.execute always returns None.

To get the value from the SQL statement, you have to use cursor.fetchone() (or fetchall()).

See the documentation, although note that this doesn't actually have anything to do with Django, but is the standard Python SQL DB API.

edited Jan 9, 2019 at 8:11

Igor Jerosimić

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answered Mar 27, 2011 at 18:19

Daniel Roseman

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