#28756: QuerySet API .extra( ) usage for FIELD + ORDER BY of queryset
-----------------------------------------+--------------------------------
Reporter: Brandon | Owner: nobody
Type: Uncategorized | Status: new
Component: Uncategorized | Version: 1.11
Severity: Normal | Keywords: QuerySet.extra
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-----------------------------------------+--------------------------------
I have reoccurring situation, when in a view.py function I need a queryset
ordered by a set of identifiers. The order of those identifiers is
dependent on factors outside of my control. Essentially in my view I am
using modelformset_factory to generate a modelformset, then the usage of
that modelformset instance requires queryset. It is that final queryset
that must be ordered by the identifier whose order is externally
determined.
So I use the .extra( ) function like below:
{{{#!python
quali_results =
ToxicologyCaseQualitativeResult.objects.filter(case_id=case.id).select_related('test').order_by('test__name')
field_list =
["AMPHS","BARB","BNZ","BE","Ecstasy","METH","6AM","PCP","THC"] #Usually
populated via retrieval of user settings.
if len(field_list) > 0:
field_list = field_list + [q.test.identifier for q in quali_results]
fields = '"'+'","'.join(str(field) for field in field_list)+'"'
field_sql = "FIELD(`identifier`,"+fields+")"
quali_results = quali_results.extra(select={'field_sql' : field_sql},
order_by=['field_sql'])
quali_resultfs = QualitativeResultFormset(queryset=quali_results,
prefix='quali_results')
}}}
If there is a better way to do this, I would be happy to change.
Cheers!
--Brandon
--
Ticket URL: <https://code.djangoproject.com/ticket/28756>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
--
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-updates/073.7b80c3d06ea101c9247a7bc201807c05%40djangoproject.com.
For more options, visit https://groups.google.com/d/optout.
