python - How to do multiple exclude commands using itertools.chain in Django? -


suppose wanna run exclude command repeatedly getting variables exclude_list e.g. ['aa', 'ab' 'ac'].

i can using loop:

for exclude_value in exclude_list:      myqueryset.exclude(variable__startswith=exclude_value)

however, i'd using itertools.chain command i've read capable of doing so. suggestions?

what doing correct approach - except 1 small detail, aren't retaining excludes. django querysets lazily evaluated, running through loop , continually chaining won't anything, right until try access set.

if this:

qs = mymodel.objects exclude_value in exclude_list:     qs = qs.exclude(variable__startswith=exclude_value)  qs = none

the database never hit.

so this:

qs = mymodel.objects exclude_value in exclude_list:     qs = qs.exclude(variable__startswith=exclude_value)  qs.count() # or whatever want queryset

and should fine, if/when experience database slowdown, ill because of large number of freetext expressions in query, profiling, can find efficiency.

but i'd wager above code sufficient needs.


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