#28019: Django django.db.models.Model.save() logic bit illogical?
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Reporter: Jacek | Owner: nobody
Kałucki |
Type: Bug | Status: new
Component: Database | Version: 1.10
layer (models, ORM) |
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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In code below, calling “Foo(name='Foo Bar').save()” method raises
ValueError “Cannot force an update in save() with no primary key” - let’s
check what goes wrong here:
1) I didn’t pass any parameters so why logic mentions about “force” and
“update” since I’m not forcing nor updating but inserting new data row?
I’ve figured out that logic adds fields to “update_fields” parameters
itself and in this case it’s a “name” which is class Foo property name.
It won’t happened if there is no class inheritance scenario. Why? But it
leads us to the next point.
2) Let’s check when the “not pk_set and (force_update or update_fields)”
condition is fulfilled.
IMHO if “pk_set” is false there is no need to check “update_fields”
because it’s never used in this scenario, it may be used only in case of
“pk_set” equals true but these states are mutually exclusive.
My proposal is to revise “get_deferred_fields()” method to handle class
attributes correctly in case of inheritance and remove redundant
“update_fields” checking on inserts.
{{{
#!div style="font-size: 80%"
Code highlighting:
{{{#!python
class Bar(models.Model):
name = models.CharField(max_length=100, blank=True)
class Foo(Bar):
first_name = models.CharField(max_length=50, blank=True)
last_name = models.CharField(max_length=50, blank=True)
def __init__(self, *args, **kwargs):
name = kwargs.get('name')
if name:
(first_name, last_name) = name.split()
kwargs['first_name'] = first_name
kwargs['last_name'] = last_name
super(Foo, self).__init__(*args, **kwargs)
@property
def name(self):
names = (self.first_name, self.last_name)
return " ".join(x for x in names if x)
@name.setter
def name(self, value):
(self.first_name, self.last_name) = value.split()
}}}
}}}
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Ticket URL: <https://code.djangoproject.com/ticket/28019>
Django <https://code.djangoproject.com/>
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