id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
22858	Maximum Recursion Depth Exceeded When Model __init__ Uses Fields Not Included In only(...)	pkenjora@…	nobody	"'''This line of code throws the error :'''

{{{
[p.date_updated for p in Project.objects.all().only('slug', 'date_updated').select_related('projectimage_set')] \ # REMOVE ONLY AND ERROR GOES AWAY
}}}

'''I've narrowed this down to a specific line in my models.py that triggers the issue as well in combination with the above.'''

The issue seems to be that when only(...) is used and a function like __init__ references a model field not included in the only list, a recursion error occurs.

{{{
class Project(models.Model):
  title = models.CharField(max_length=100, unique=True)
  slug = models.SlugField(blank=False, max_length=100, unique=True, editable=False)
  description = models.CharField(blank=True, max_length=155, editable=False)
  summary = models.TextField(help_text=""Describe the project in 3-4 sentences."")

  image_x = models.PositiveIntegerField(blank=True, editable=False, default=1)
  image_y = models.PositiveIntegerField(blank=True, editable=False, default=1)
  image = models.ImageField(upload_to='projects', height_field='image_y', width_field='image_x', storage=S3Storage(bucket=settings.AWS_BUCKET, size=(1000, 1000)), blank=True)

  car = models.ForeignKey(Car, blank=True, null=True)
  parts = models.ManyToManyField(Part);
  faqs = models.ManyToManyField(FAQ, blank=True);

  views = models.PositiveIntegerField(default=0, editable=False, db_index=True)
  sequence = models.PositiveIntegerField(blank=True, default=0)
  date_updated = models.DateField(auto_now=True)

  notify = models.TextField(blank=True, help_text=""List of emails seperated by spaces or commas to notify when project is updated."")

  #old_notify = None
  #old_date_updated = None

  class Meta:
    ordering = ['sequence']

  def __unicode__(self):
    return self.title

  def clean(self):
    self.slug = slugify(self.title)

  def __init__(self, *args, **kwargs):
    super(Project, self).__init__(*args, **kwargs)
    self.old_notify = self.notify  # COMMENT THIS LINE OUT AND IT WORKS OK
    self.old_date_updated = self.date_updated
}}}

'''The stack trace is....'''

http://dpaste.com/0HWY6TZ

Professional Plea: There are some circles who claim using __init__ on a model is not ""Pythonic"".  Neither is a maximum recursion error when you follow ""syntax"".  This use of __init__ is VERY COMMON as a clean quick alternative to signals.  If there really is no fix please update the Django documentation to specifically call out that __init__ will throw this issue when used with only(...) to discourage the use of __init__ or at least save people hours of bug hunting.
"	New feature	closed	Documentation	1.6	Normal	wontfix	recursion only init		Unreviewed	0	0	0	0	1	0