#27267: Renaming a primary key fails with "cannot drop constraint on table
because
other objects depend on it"
--------------------------------+--------------------------------------
Reporter: Melvyn Sopacua | Owner: nobody
Type: Bug | Status: new
Component: Migrations | Version: 1.8
Severity: Normal | Resolution:
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
--------------------------------+--------------------------------------
Comment (by Melvyn Sopacua):
Setting preserve_default to True or omitting the keyword argument still
results in the DROP DEFAULT statement being emitted. I executed the
statements from sqlmigrate without the DROP DEFAULT part to get out of the
catch-22. As you can see in the initial comment this was also a table that
ran into the drop contraint error.
I'm still baffled what makes this model and the item model different so
that we can get to the root cause.
For completeness here's the model definition:
{{{#!python
class DpeCharacter(
uni_factory(max_length=32, verbose_name=_('name of character'))
):
character_id = models.AutoField(primary_key=True)
char_class = models.ForeignKey(
CharacterClass, related_name='class_characters',
)
account = models.ForeignKey(
'DpeAccount', models.CASCADE,
related_name='my_characters',
null=True, blank=True,
)
level = models.PositiveSmallIntegerField(
verbose_name=_('current level'),
validators=(
MinValueValidator(1, 'Minimum level is 1'),
MaxValueValidator(105, 'Maximum level is 105'),
)
)
avatar = models.ImageField(
verbose_name=_('avatar picture'),
help_text=_('Square JPEG or PNG format, min 32x32, max 128x128
pixels'),
upload_to=avatar_upload_to,
height_field='avatar_height',
width_field='avatar_width',
null=True, blank=True,
)
avatar_height = models.PositiveSmallIntegerField(
validators=(
MinValueValidator(32, 'Avatar image too small.'),
MaxValueValidator(128, 'Avatar image too tall.'),
),
null=True, blank=True,
)
avatar_width = models.PositiveSmallIntegerField(
validators=(
MinValueValidator(32, 'Avatar image too narrow'),
MaxValueValidator(128, 'Avatar image too wide'),
),
null=True, blank=True,
)
def __str__(self):
return '{} ({}-{})'.format(
self.name, self.char_class.abbreviation, self.level
)
def clean(self):
if self.avatar is not None:
if self.avatar_height != self.avatar_width:
raise ValidationError({'avatar': 'Image should be
square'})
class Meta:
verbose_name = _('character')
verbose_name_plural = _('characters')
app_label = 'dpe'
}}}
And uni_factory:
{{{#!python
class UniquelyNamedItemManager(models.Manager):
def get_by_natural_key(self, name):
return self.get(name=name)
class PagedUniquelyNamedItemManager(PageManager,
UniquelyNamedItemManager):
pass
def uni_factory(**kwargs):
defaults = {
'verbose_name': _('name'),
'help_text': _('must be unique'),
'is_paged': False,
}
defaults.update(kwargs)
if defaults.pop('is_paged', False):
manager = PagedUniquelyNamedItemManager
else:
manager = UniquelyNamedItemManager
class UniquelyNamedItemMixin(models.Model):
objects = manager()
name = UniqueNameField(**defaults)
def __str__(self):
return self.name
def natural_key(self):
return self.name
class Meta(models.base.ModelBase):
app_label = 'dpe'
abstract = True
return UniquelyNamedItemMixin
}}}
And finally, UniqueNameFIeld:
{{{#!
class UniqueNameField(CharField):
title_transform = True
max_length = 63
def __init__(self, title_transform=True, *args, **kwargs):
kwargs['unique'] = True
kwargs['max_length'] = kwargs.get('max_length', self.max_length)
self.title_transform = title_transform
super(UniqueNameField, self).__init__(*args, **kwargs)
def deconstruct(self):
name, path, args, kwargs = super(CharField, self).deconstruct()
kwargs['title_transform'] = self.title_transform
return name, path, args, kwargs
def pre_save(self, model_instance, add):
name = super(UniqueNameField, self).pre_save(model_instance, add)
if self.title_transform:
name = name.title()
setattr(model_instance, self.name, name)
return name
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/27267#comment:12>
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