CODEWITHSUNDEEP
pythondjangodjango-views
csandreas1
csandreas1

Reputation: 2378

Django default queryset values shorthand

I am initializing variables to None as default value. If the queryset returns no objects then the program will not fail.

Is there a shorter method on this? Thanks

  qs_data = {
        'flal_id_no' : None,
        'mail_id_no' : None,
        'subject_id_no':None,
        'pdsbj_id_no':None,
    }

    qs = vFileAllocation.objects.values().filter(track_id_no=get_track_id_no)[0]

    if qs:
        qs_data['flal_id_no'] = qs['flal_id_no']
        qs_data['mail_id_no'] = qs['mlal_id_no']
        qs_data['subject_id_no'] = qs['subject_id_no']
        qs_data['pdsbj_id_no'] = qs['pdsbj_id_no']

Upvotes: 0

Views: 196

Answers (1)

Oleg Russkin
Oleg Russkin

Reputation: 4404

Basic python or operator (return default if None) can be used:

queryset[0] - gets first object from the queryset result, so in case no matches found - queryset will contain no elements (queryset == <QuerySet[]>) and getting first element from it [0] will fail.

Correct way is to use .first() on queryset to evaluate it and get first result or None.

For this example this can be done as a one-liner:

qs_data = vFileAllocation.objects.values() \
    .filter(track_id_no=get_track_id_no) \
    .first() or qs_data

or

qs = vFileAllocation.objects.values() \
    .filter(track_id_no=get_track_id_no).first()
# qs is already evaluated
qs_data = qs or qs_data
  • Fixed answer thanks to @csandreas1 comment

Upvotes: 1

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