I had a post on this recently that you would probably find relevant,
see:
http://groups.google.com/group/django-users/browse_frm/thread/582f21486c1073eb/8af00e9c0577a5e6?lnk=gst&q=margie#8af00e9c0577a5e6
Or search for "deletion of distant related objects" in this group.
I'm still somewhat confused on how to deal with this at a high level,
in an environment where one has apps that are written separately from
each other. For example, suppose developer A writes an app called
"BookStore" that contains a Book model. Now suppose developer B
integrates BookStore into his/her own "Book Club", and has a Reader
model that references the Book model through a foreign key. It seems
to me that if the BookStore app provides a ui for deleting books, that
this has the very negative consequence of deleting Readers, which
probably isn't what the Book Club developer wants.
In my other post Malcolm gave me some pointers for finding all of the
fields that reference a particular key. IE, if the the BookStore app
wants to provide a ui for deleting Books, it could find all fields
that reference Books through a foreign key, and set those foreign keys
to null prior to deleting the Books. This would work, however it
makes certain very nice parts of Django unusable - namely the
formsets. Suppose I have a formet of books and want to use the Delete
funcionality of the formset. It's not clear to me if/how I can set
all fields that reference Books through a foreign key to null, prior
to the automatic delete getting called. Perhaps I just have to
sacrifice the automatic delete and have my own delete checkbox in the
formset forms, and when I see that I set all the foreign keys to null.
I am just now going into production with my app, and trying to figure
out what model to present to my users. Currently I have a bunch of
formsets but have told my users "Don't use Delete!" (Of course I can
remove the Delete checkbox - and I will). But I'm curious what the
plan going forward is for all of this. I have seen disucssion on the
developers group about it but it is not clear to me if there is a plan
or if it has been tabled or if it is still in discussion.
Would love to hear a summary of where this might be going from any
developers! I realize it is a tough problem - not complaining here.
Just trying to get a grip on what do do in my own app and whether
there are any changes coming and if so, what they would be and what
the timeframe might be.
Margie
On Apr 28, 10:57 pm, Vincent <pho...@gmail.com> wrote:
> Hi,
> I got a problem like this:
>
> class A(models.Model):
> id = models.AutoField(primary_key=True)
> field1 = models.TextField()
>
> class B(models.Model):
> a = models.ForeignKey(A)
> field1 = models.TextField()
>
> then there are some records of A/B,
> how can i delete records of A and do not delete records of B which have
> foreignkey on A
>
> Maybe i could change 'a = models.ForeignKey(A)' to ' a =
> models.IntegerField("A") '.
>
> Is it a suitable way for this problem?
>
> Thanks for your suggestion.
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