Hi, I have a Django newbie question.
My goal is to auto increment primary key with non Django standard column
name.
We are converting from existing database and primary key schema is
"tablename_key" and not "id".
I googled it and end up reaching to this ticket:
https://code.djangoproject.com/ticket/13295
So I understand that there is work in progress but I wanted find work
around..
1. My first try was to let postgres handle it.
my postgreSQL table looks like this:
CREATE TABLE poll
(
poll_key integer NOT NULL DEFAULT nextval('poll_key_seq'::regclass),
poll_question character varying(200) NOT NULL,
poll_pub_date timestamp with time zone NOT NULL,
CONSTRAINT poll_pkey PRIMARY KEY (poll_key)
)
My model look like this:
class Poll(models.Model):
poll_key = models.IntegerField(primary_key=True)
poll_question = models.CharField(max_length=200, default='')
poll_pub_date = models.DateTimeField('date published',
default=datetime.date.today())
class Meta:
db_table = u'poll'
I was hoping that with this, I could
p = Poll(poll_question="Question 1?")
p.save()
but this fails because Django is actually sending the following statement:
INSERT INTO "poll" ("poll_key", "poll_question", "poll_pub_date")
VALUES (NULL, 'Question 1?', NULL)
2. My Second attempt is then to add default to model
Created a function to return sequence value
from django.db import connection
def c_get_next_key(seq_name):
""" return next value of sequence """
c = connection.cursor()
c.execute("SELECT nextval('%s')" % seq_name)
row = c.fetchone()
return int(row[0])
Calling like below works just fine. Everytime I call it, I get new number.
c_get_next_key('poll_key_seq')
Then I modify Poll_key in Poll model as follows:
Poll_key = models.IntegerField(primary_key=True,
default=c_get_next_key('poll_key_seq'))
I went to Django Shell and created first record.
p1 = Poll(poll_question="P1")
p1.poll_key
# this will return let's say 37
p1.save()
# saves just fine.
# instantiating new object
p2 = Poll(poll_question="P2")
p2.poll_key
# this also return 37.
I know I must be doing something wrong... but could you pint me to right
direction? I am expecting p2.poll_key to return 38.
Thank you very much for your help in advance.
Naoko
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