On Friday 07 July 2006 12:57, Malcolm Tredinnick wrote:
> Maybe there is some oddity about your circumstances. Can you post more
> details if you are really seeing NULL values being treated distinctly,
> please?
Actually, it may not been SQLite related, after all. I narrowed the problem to
the way the admin interface create empty fields in the database. Those NULL
values are not really NULL.
Here's my model:
-------------------------------------------------------------------------------
class Foo(models.Model):
bar = models.CharField(maxlength = 63, unique=True, blank=True, null=True)
def __str__(self):
return str(self.bar)
class Admin:
pass
-------------------------------------------------------------------------------
Creating several Foo objects with no bar property works correctly in python
interpreter:
-------------------------------------------------------------------------------
>>> Foo(bar='bar').save()
>>> Foo().save()
>>> Foo().save()
>>> Foo.objects.all()
[<Foo: bar>, <Foo: None>, <Foo: None>]
-------------------------------------------------------------------------------
That's ok.
And moreover, if I try to create an other Foo with bar='bar', I get
the 'column bar is not unique' IntegrityError exception.
But if I try the same in the admin interface, I get:
-------------------------------------------------------------------------------
Traceback (most recent call last):
File "/home/kilian/django/django/core/handlers/base.py" in get_response
74. response = callback(request, *callback_args, **callback_kwargs)
File "/home/kilian/django/django/contrib/admin/views/decorators.py" in
_checklogin
55. return view_func(request, *args, **kwargs)
File "/home/kilian/django/django/views/decorators/cache.py" in
_wrapped_view_func
40. response = view_func(request, *args, **kwargs)
File "/home/kilian/django/django/contrib/admin/views/main.py" in add_stage
257. new_object = manipulator.save(new_data)
File "/home/kilian/django/django/db/models/manipulators.py" in save
101. new_object.save()
File "/home/kilian/django/django/db/models/base.py" in save
204. ','.join(placeholders)), db_values)
File "/home/kilian/django/django/db/backends/util.py" in execute
12. return self.cursor.execute(sql, params)
File "/home/kilian/django/django/db/backends/sqlite3/base.py" in execute
77. return Database.Cursor.execute(self, query, params)
-------------------------------------------------------------------------------
IntegrityError at /admin/test/foo/add/
column bar is not unique
/home/kilian/django/django/db/backends/sqlite3/base.py in execute
return Database.Cursor.execute(self, query, params) ...
▼ Local vars
Variable
Value
params
['']
query
'INSERT INTO "test_foo" ("bar") VALUES (?)'
self
<django.db.backends.sqlite3.base.SQLiteCursorWrapper object at 0xb5f62c2c>
-------------------------------------------------------------------------------
It seems that blank admin fields are passed as empty strings rather than real
NULL values. In the command-line, it would give something like:
-------------------------------------------------------------------------------
>>> Foo(bar='').save()
>>> Foo(bar='').save()
Traceback (most recent call last):
File "<console>", line 1, in ?
File "/home/kilian/django/django/db/models/base.py", line 204, in save
','.join(placeholders)), db_values)
File "/home/kilian/django/django/db/backends/util.py", line 12, in execute
return self.cursor.execute(sql, params)
File "/home/kilian/django/django/db/backends/sqlite3/base.py", line 77, in
execute
return Database.Cursor.execute(self, query, params)
IntegrityError: column bar is not unique
-------------------------------------------------------------------------------
Frommy point of view, the admin interface should probably create db records
with NULL values for fields left blank in the interface, if (and only if?)
null=True *and* blank=True.
If blank=True and null=False, empty admin fields should indeed be stored as
empty strings (or whatever the db field was defined to). And I can't find any
example where the (blank=False and null=True) case could be used.
Perhaps there are other situations I didn't think of where this is not the
right thing to do, I don't know.
Best regards,
--
Kilian CAVALOTTI Administrateur réseaux et systèmes
UPMC / CNRS - LIP6 (C870)
8, rue du Capitaine Scott Tel. : 01 44 27 88 54
75015 Paris - France Fax. : 01 44 27 70 00
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