I was wondering what people thought of adding a .exists() method to
querysets that would take another QuerySet, and add a "WHERE EXISTS
(SELECT ...)" to the original query. It would require that the passed-
in QuerySet be joinable with the original QuerySet via a ForeignKey
relationship. Take the following example:
class Record (models.Model):
name = models.CharField( max_length=100 )
active = models.BooleanField()
class RecordValue (models.Model):
record = models.ForeignKey( Record, related_name='values' )
value = models.TextField()
Now suppose you want to build a search engine. Searching for
Record.name='Dan' would be easy, and searching for Records with a
RecordValue.value='django' is also [slightly less] easy. But the
latter requires using a RecordValue queryset, and extracting the
records from it. So I thought it would be nice to be able to do
something like:
Record.objects.filter( name='Dan' ).exists( RecordValue.objects.filter(
value='django' ) )
I'm not sure how difficult it would be to implement, but I'd be
willing to take a stab at it (against qs-rf once it's merged and/or
stabilized) if it's of interest to anyone.
Dan
Note: This is unrelated to
http://groups.google.com/group/django-developers/browse_frm/thread/5490f8736cc54c27/893ba34ec554bfc3
(although, interestingly, the name "any" was suggested in the that
thread, which is what SQLAlchemy calls what I describe above - don't
really care what the method is called)
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Django developers" group.
To post to this group, send email to django-developers@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-developers?hl=en
-~----------~----~----~----~------~----~------~--~---
