How to remove extra ',' in tuple in django

Question

I have one problem in building a list of id using django. if i choose more than 1 id it ok but if i choose only one it will produce extra ',' in list.

testa = tuple([k['id'] for k in queryset.values('id')])
print testa

if in the queryset have exactly 1 id, it will display

(1234,)

other than that it ok

(1234,1244)

How can i remove extra ', in list'

Answer 1

(1234,)

is the correct Python representation of a 1-tuple. (1234) would be wrong as that is taken as a simple integer in mathematical parentheses, evaluating to 1234, not a tuple containing it.

This is different for lists because the square brackets don't have this double purpose of also meaning mathemtical order-of-operations, so whilst [1234] and [1234,] are both valid representations of a length-1-list, the default textual representation can be without the extra comma.

If you are devising your own textual representation of a tuple that does not need to be the same as Python's, you could do eg.:

'(%s)' % ', '.join(map(repr, testa))

Answer 2

To write a tuple containing a single value you have to include a comma, even though there is only one value.

You can index the tuple to get the desired output:

print testa[0]
>>>> 1234

Answer 3

thats' how python displays the tuples with single values , also note that the recommended syntax for creating a tuple with single value is also x = (1,) that helps in differentiating a tuple from a function call . If you really want an output like you describe you can try

testa = tuple([k['id'] for k in queryset.values('id')])
if len(testa)==1:
     print '(%s)'%testa[0]
else:
     print testa

Answer 4

Yo say you want a list but de facto you are creating a tuple.

To get a list of ids take a look at values_list

>>> Entry.objects.values_list('id', flat=True).order_by('id')
[1, 2, 3, ...]
>>> Entry.objects.filter(id=1).values_list('id', flat=True)
[1]

Answer 5

actually you don't have to. the colon sign is just there in a string representation of the tuple. For example you can just create your own string by

print "(%s)" % ",".join(testa)