Re: OperationalError: (1054, "Unknown,column ' ...) for ForeignKey
Thanks a lot for your help Malcom. Malcolm Tredinnick escribió, El 18/08/2008 0:03: > > On Sun, 2008-08-17 at 23:51 +0200, MarC wrote: >> Hi again, >> I'm still fighting against it and reading related posts in the mailing list >> archive with no >> success... Now I just found it won't work either for a simpler example. >> Looks like I should be doing something really stupid but I can't see it... >> >> from django.db import models >> >> class Test2(models.Model): >> name = models.CharField(max_length=50); >> def __unicode__(self): >> return self.name >> >> class Test(models.Model): >> name = models.CharField(max_length=50); >> rel = models.ForeignKey(Test2); > >> def __unicode__(self): >> return self.name >> >> SHELL: >> >>> from trustworker.main.models import * >> >>> t2=Test2(name="sample"); >> >>> t=Test(name="example",rel=t2); >> >>> t2.save(); >> >>> t.save(); > > This is caused by an implementation detail, but the basic rule is "don't > use unsaved objects as related objects". > > What's going on is when you do the "rel=t2" part, the related field > attribute actually extracts the value it will be storing (the primary > key value of t2, in this case) and stores that. It doesn't store the > reference to t2 directly on the attribute (it does store the reference > internally for caching reasons, but that's beside the point here). > > Since t2 is unsaved, it's primary key attribute is None and that's why > the wheels fall off later. Saving t2 prior to using it to construct t > will almost certainly fix the problem. > > Yes, this is slightly odd and a little trappy. > > Regards, > Malcolm > > > > > > --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~--~~~~--~~--~--~---
Re: OperationalError 1054 Unknown column
Hum... I thought that to be an AutoField it was mandatory that "_id" would have to be added to the name of the field... Apparently not! :) Thanks. Ana On Aug 9, 6:57 pm, Collin Grady <[EMAIL PROTECTED]> wrote: > Why did you add _id to your model definition for levelID ? The column > does not have that. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~--~~~~--~~--~--~---
Re: OperationalError 1054 Unknown column
Why did you add _id to your model definition for levelID ? The column does not have that. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~--~~~~--~~--~--~---
OperationalError 1054 Unknown column
Hi all,
I'm working with a MySQL legacy DB which was changed.
This was our previous Level table:
+-+---+--+-+-+---+
| Field | Type | Null | Key | Default | Extra |
+-+---+--+-+-+---+
| level_name | varchar(20) | NO | PRI | | |
| instrument_name | varchar(20) | NO | PRI | | |
| available | enum('Y','N') | NO | | Y | |
| tablename | varchar(20) | YES | | NULL| |
+-+---+--+-+-+---+
This was the previous model class for the Level table:
class Level(models.Model):
level_name = models.CharField(primary_key=True, maxlength=60)
instrument_name = models.CharField(blank=False, maxlength=60)
available = models.TextField(blank=False)
tablename = models.CharField(blank=True, maxlength=60)
Because in the database the primary key was made of two fields, the
level_name and the instrument_name this wasn't working properly. So we
changed the table to:
+-+---+--+-+-
++
| Field | Type | Null | Key | Default |
Extra |
+-+---+--+-+-
++
| level_name | varchar(20) | NO | MUL |
||
| instrument_name | varchar(20) | NO | |
||
| available | enum('Y','N') | NO | | Y
||
| tablename | varchar(20) | YES | | NULL
||
| levelID | bigint(20)| NO | PRI | NULL|
auto_increment |
+-+---+--+-+-
++
and the Level model class to (with the help of the inspectdb command):
class Level(models.Model):
level_name = models.CharField(unique=True, maxlength=60)
instrument_name = models.CharField(unique=True, maxlength=60)
available = models.TextField()
tablename = models.CharField(blank=True, maxlength=60)
levelID_id = models.AutoField(primary_key=True)
But now, when I try to do for example this:
def view_levels(request, orderby):
levels=Level.objects.all()
levellist=[]
for l in levels:
levellist.append({'levelname':l.level_name,
'instrname':l.instrument_name,
'available':l.available,
'tablename':l.tablename})
ordering='Instrument Name'
return render_to_response('view_levels.html',
{'levellist':levellist, 'ordering':ordering})
It gives me this error:
Exception Type: OperationalError
Exception Value:(1054, "Unknown column 'Level.levelID_id' in 'field
list'")
Exception Location: /nobackup/reis/Python/lib/python2.5/site-packages/
MySQLdb/connections.py in defaulterrorhandler, line 35
What is happening here?
Thanks for your time!
Ana
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