Thomas
Thanks for replying
On 19/12/2012 12:06am, Thomas Orozco wrote:
Hi,
Could you provide the following information?
- What's the relationship between A and B (model code of the field,
if there is, would be great)
There is no relationship at all. A and B are separately and
independently related to Item.
A and B are actually copied from 'a' and 'b' which *are* related but
exist purely as a stand-alone reference. When Item gets an A record (and
it can have many) it is copied from its 'a' reference record. Item then
automatically gets copies of all the corresponding 'b' reference records
as B records - except duplicates are semi-skipped.
Where a duplicate would have occurred, I append the A_code into a
special field on the B record to indicate which A records were/are
"interested" in that B record. When A records are deleted, it is
necessary to delete their corresponding B records - unless another A
record is still interested in which case we just remove the deleted
A_code from the special field.
I could send you the model code off-list if you wish.
- The code of your pre_delete signal handler / the method it calls.
# this lives in models.A_Part.py # # #
from django.db.models.signals import pre_delete, post_delete
def cleanup_bparts(sender, instance, **kwargs):
instance.item.delete_bparts(a_code=instance.a_code)
pre_delete.connect(cleanup_bparts, sender=A_Part, weak=False)
#post_delete.connect(cleanup_bparts, sender=A_Part, weak=False)
# # # # # # # # # # # #
... and the item.delete_bparts() code ...
def delete_bparts(self, a_code):
qs_bpart = B_Part.objects.filter(item=self,
a_partcodes__contains=a_code)
for bpart in qs_bpart:
acodes = bpart.a_partcodes.split()
if len(acodes) == 1:
bpart.delete()
else:
acodes.remove(a_code)
bpart.a_partcodes = ' '.join(acodes)
bpart.save()
I think you have a ForeignKey field that is required or limited and that
is causing the ValidationError.
Indeed, that line 988 is in the code for ModelChoiceField
I have been through all the fk fields and they are all null=True,
blank=True and in Postgress each _id column is nullable.
I also had an ordering sequence on some of the models and I removed all
that as well.
As mentioned earlier, embedded print statements seem to prove the
delete_bparts() code is working nicely.
When I comment out the pre-delete connection, the A_Part record gets
delete as expected - but obviously it doesn't clean up the B records.
Thanks ....
Mike
Best,
Thomas
2012/12/17 Mike Dewhirst <mi...@dewhirst.com.au
<mailto:mi...@dewhirst.com.au>>
I'm getting a baffling ValidationError.
Request URL: http://127.0.0.1:8000/admin/__assembly/item/4/
<http://127.0.0.1:8000/admin/assembly/item/4/>
Django Version: 1.4.3
Exception Type: ValidationError
Exception Value: [u'Select a valid choice. That choice is not
one of the available choices.']
Exception Location:
C:\usr\bin\lib\site-packages\__django\forms\models.py in to_python,
line 988
Python Version: 2.7.3
Background ...
I have an Item model which has two one-to-many relationships with
other types of child records (call them A and B models).
In the Admin, when the user adds an A record, some B records get
added automatically.
The next A record to get added does much the same but if there are
any B duplicates it doesn't try to add those but instead just adds
its mark to a special field in the B record which is already there.
My code - which from embedded print statements appears to be doing
exactly what I want - will either delete the B record or just remove
the mark previously added. Eventually when the last A record is
deleted the idea is that the last B records will go at the same time.
Unfortunately, at the final hurdle we get the ValidationError at
line 988 in to_python.
The local vars nominate ...
self <django.forms.models.__ModelChoiceField object at 0x00F5DE70>
value u'251'
key 'pk'
... and that is the pk of the A record which triggers the Item code
via a pre_delete signal.
Summarising:
- the deletion/mark removal method lives in the Item model
- the pre-delete signal is detected in the A record
- the signal connects a stub method in the A record
- the stub method in the A record calls the Item method
- the Item method iterates over a filtered queryset of B records and
uses the passed value (the aforesaid mark from the A record) to
decide whether to delete the B record or just remove the mark and
save it
None of my code appears in the TraceBack so I assume the Admin is
trying to delete the A record. I've tried both pre_delete and
post_delete signals in the A record.
Why is it so?
Thanks for any hints
Mike
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