Django admin does update instead of insert - django

Question

My models are the following:
class Station(models.Model):
sid = models.IntegerField(primary_key=True)
uid = models.ForeignKey('User', db_column='uid', verbose_name='User')
name = models.CharField(max_length=100)
# and others...
class Meta:
managed = False
db_table = 'Stations'
class Playlist(models.Model):
plid = models.IntegerField(primary_key=True)
name = models.CharField(max_length=200)
changed = models.BooleanField(default = False)
def __unicode__(self):
return self.name
class Meta:
managed = False
db_table = 'Playlists'
class Stationplaylist(models.Model):
spid = models.IntegerField(primary_key=True, db_column='spid')
sid = models.ForeignKey(Station, db_column='sid')
plid = models.ForeignKey(Playlist, db_column='plid')
syncronized = models.BooleanField()
def __unicode__(self):
return self.plid.name
class Meta:
managed = False
db_table = 'StationsPlaylists'
unique_together=('sid', 'plid')
and I want to perform insert operation in my view:
def addPlaylist(request, app_label='webadmin', **kwargs):
# stuff...
selected_playlists = request.POST.getlist('selected_playlists[]')
current_station = request.POST.get('station')
totalPlaylists = Stationplaylist.objects.filter(sid=current_station).count()
last_spid = None
for playlist in selected_playlists:
if playlist != 'on':
if totalPlaylists==0:
last_spid=1
elif last_spid == None:
last_obj = Stationplaylist.objects.order_by('-pk')[0]
last_spid = last_obj.spid + 1
else:
last_spid += 1
Stationplaylist(last_spid, current_station, playlist, 0).save() # 0-syncronized
totalPlaylists+=1
return HttpResponse('OK')
but when I call this for, say Station#1, with 3 playlists and then I call this on another one, let it be Station#2, the playlists are simply updated. I mean, in database, their station field is updated to the Station#2.
Why is that happening and how to solve it?
Thanks in advance

Answer 1

You've overridden the automatic primary key and made it a pure IntegerField. This doesn't autoincrement, so every new instance gets the same default primary key.
You really shouldn't define your own primary key field unless you have a really good reason. But if you do have that good reason, you should use AutoField rather than IntegerField.