Malcolm Tredinnick <[EMAIL PROTECTED]> writes:
> On Sat, 2007-02-10 at 03:34 -0500, David Abrahams wrote:
>>
>> In my attempt to use
>>
>> ForeignKey(Track, null=True)
>>
>> When I actually tried to use a null Track value, I got:
> [...traceback snipped...]
>>
>> ProgrammingError at /admin/program/session/15/
>> ERROR: invalid input syntax for integer: "" SELECT
>> "program_session"."id","program_session"."title","program_session"."short_title","program_session"."description","program_session"."start_id","program_session"."track_id","program_session"."duration"
>> FROM "program_session" INNER JOIN "program_timedivision" AS
>> "program_session__start" ON "program_session"."start_id" =
>> "program_session__start"."id" WHERE ("program_session__start"."id" ILIKE
>> '40' AND "program_session"."track_id" = '')
>>
>> My wild guess here is that this happens because track_id is the primary key
>> and thus expects an integer value; had I made the track name its
>> primary key it might've worked (?). Anyway, if I want to make that
>> change at this point, I don't know how to do so without losing my
>> valuable data. Any help you can offer me would be very much
>> appreciated.
>
> Can you give a little more information about how you triggered this
> error? It looks like you are doing something in the admin,
I am. I'm saving an existing Session object after setting its Track
to the "------" entry in the pop-up used for track selection. I get
a similar effect when creating a new Session without setting the
Track.
> but I am using null=True foreign keys through the admin successfully
> without doing anything special, so it's not totally impossible. It
> shows up fine in the admin system and the database stores the
> reference as a NULL (in my case). And I'm using PostgreSQL, too, so
> it's not a db-specific thing that I can see (although I'm using
> psycopg1, not psycopg2).
>
> If you triggered the problem just by trying to add a record in the admin
> and leaving the "track" reference field empty, it's going to be a little
> hard to debug remotely.
My models.py is enclosed. It doesn't have any special dependencies.
Would you mind trying to reproduce the problem?
> Try creating a smaller project with a trimmed
> down model -- doing the standard "remove stuff until it starts working
> or you are only left with the ForeignKey" process.
I'll see if I can do that.
> I can't place what portion of the admin is generating the query you are
> seeing, so any information you can provide would be useful.
The endlosed models.py ought to be sufficient.
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from django.db import models
class Speaker(models.Model):
last_name = models.CharField(maxlength=100)
first_name = models.CharField(maxlength=100)
email = models.EmailField()
bio = models.TextField()
class Meta:
ordering = ('last_name','first_name','email')
class Admin:
pass
# list_display = ('first_name', 'last_name')
def __str__(self):
return self.first_name + ' ' + self.last_name
class Track(models.Model):
name = models.CharField(maxlength=100, primary_key=True)
description = models.TextField()
class Admin:
list_display = ('name', 'description')
def __str__(self):
return self.name
class TimeDivision(models.Model):
when = models.DateTimeField()
starts_break = models.BooleanField()
name = models.CharField(maxlength=100)
class Admin:
pass
# list_display = ('name', 'when', 'starts_break')
class Meta:
ordering = ('when',)
def __str__(self):
return self.when.strftime('%A') + ' ' + self.name
class Session(models.Model):
title = models.CharField(maxlength=200)
speakers = models.ManyToManyField(Speaker, filter_interface =
models.HORIZONTAL, related_name='Sessions')
short_title = models.CharField(maxlength=50,blank=True)
description = models.TextField()
start = models.ForeignKey(TimeDivision)
track = models.ForeignKey(Track,blank=True,null=True)
duration = models.TimeField()
def __str__(self):
return ', '.join([s.last_name for s in self.speakers.all()]) \
+ ': ' + (self.short_title or self.title)
class Admin:
pass
class Meta:
# These constraints are imperfect but should catch many common errors
unique_together = (
('start','track'), # only one session may start in a given
# track at a given time
# ('speakers', 'start'), # a given speaker can only start one
# session at a time
('title',), # no two sessions can have the same title
)
--
Dave Abrahams
Boost Consulting
www.boost-consulting.com
