Hi Seemant,
> >http://www.djangoproject.com/documentation/model_api/#unique-togetherI guess
> >I must have read the description wrong (I still don't see how
> the description implies that a NULL field gets ignored or whatever).
No, you're right that the unique-together description does not
explicitly state how NULLs are treated.
This mainly stems from the fact that in database-land NULL is really
not a value -- it's not even an empty string. NULL denotes the lack of
any value.
If you want "to_verse" to be part of that 4-way uniqueness constraint
and to_verse can indeed be "empty", you could redefine it with a
default=0 in your model (you will need to regenerate your model). In
essence, you are saying that a NULL to_verse to you is a single value
and not a lack of value.
So, now when you leave that field blank and save Scripture, to_verse
will be stored as 0. This will make your unique_together with the 4
fields work as expected.
The caveat is that you will need to a function or property in your
model that returns an empty string from to_verse when it's zero. For
example (please note that the indentation uses 4 spaces here instead of
tabs):
def _to_verse(self):
return (self.to_verse != 0) and self.to_verse or ''
real_to_verse = property_to_verse)
The to_verse field in your model will be something like this:
to_verse = models.IntegerField (blank = True, null = True, default=0)
>
> > What happens if you try
>
> > unique_together = (('book', 'chapter', 'from_verse'),
> > ('book', 'chapter', 'from_verse', 'to_verse',))So I
> > tried this, but now, after entering Genesis 1:1-2, I can not enter
> anything that has Genesis 1:1 in it. So, Genesis 1:1 is "not unique"
> apparently, either.
>
What you are saying is that with the above unique_together spec,
Genesis 1:1 becomes unique and therefore Genesis 1:1-2 is not allowed
if Genesis 1:1 is already in the DB.
In any case, if the default=0 trick works for you, this becomes a moot
point.
-Rajesh
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Django users" group.
To post to this group, send email to django-users@googlegroups.com
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/django-users
-~----------~----~----~----~------~----~------~--~---
