How to construct Django enum filter

Question

The following is to get 1 record out of database by matching enum type.

TYPES = (
    ('ABC_ABC', 'abc abc'),
    ('XYZ_XYZ', 'xyz xyz'),
)


class Hello(models.Model):    
  type = models.CharField(max_length=8, choices=TYPES, blank=True)

database:

'1', 'ABC_ABC', 'other data'

Queryset:

qset = Q(type__in=('ABC_ABC'))
hello = models.Hello.objects.filter(qset)

Output:

print('count: {}'.format(hello.count()))

Result is 0. It should be 1. What's wrong?

alfajet · Accepted Answer · 2019-11-07 21:22:41Z

1

Try changing your Q filter as follow:

qset = Q(type='ABC_ABC')

Explanations: When using in lookup, django expects an iterable. As you provided only one value, I suspect, it tried to iterate over the string 'ABC_ABC' which is why you didn't get any hit.

If you really want to use the in lookup, which is useless in this case, you should add a comma in to force creating a 1-tuple.

qset = Q(type__in=('ABC_ABC',))

Further thoughts

As this query is quite basic, using a Q object is superfluous. You can simply call

.filter(type='ABC_ABC')

edited Nov 7, 2019 at 21:22

answered Nov 7, 2019 at 21:11

alfajet

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1 Comment

alfajet Over a year ago

If it solved your problem, maybe you could mark it as your chosen answer? ;)

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