Django combine multiple querysets (same model)

Question

I have list of querysets (all for same model):

results = Entry.objects.all()
result_elms = []
if city_list:
    for city in city_list:
    result_elms.append(results.filter(address__city__icontains=city))

if county_list:
    for county in county_list:
        results_elms.append(results.filter(address__county__icontains=county))
#other filters here, daynamically created

#how can I combine all results_elms (querysets) into one?

I know that I can use | operator to combine querysets from same model. But how can I apply it for all elements from result_elms list?

There's not enough detail in your question to give an answer. You should provide enough info for someone else to reproduce the problem, and a clear description of the result you're looking for (also the if statement is not needed). — thebjorn
– thebjorn, Commented Nov 11, 2017 at 10:08
Have you tried it using __in? That should help you. See more here — aquaman
– aquaman, Commented Nov 11, 2017 at 10:10
@thebjorn what do you mean? My exact question is how can I apply | (combine oparator) for all querysets in list. what other information should I provide? — dease
– dease, Commented Nov 11, 2017 at 10:28
Please specify what other filters you want to apply. What is the expected results? — Ammar Alyousfi
– Ammar Alyousfi, Commented Nov 11, 2017 at 10:34

thebjorn · Accepted Answer · 2017-11-11 10:48:58Z

6

You can use Q objects:

from django.db.models import Q

results = Entry.objects.all()
q = Q()
for city in city_list:
    q = q | Q(address__city__icontains=city)
results.filter(q)

The documentation (https://docs.djangoproject.com/en/1.7/topics/db/queries/#complex-lookups-with-q) has more details and examples.

edited Nov 11, 2017 at 10:48

answered Nov 11, 2017 at 10:35

thebjorn

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6 Comments

thebjorn Over a year ago

The little bit of extra info made it clear what you needed - happy to help :-)

Ammar Alyousfi Over a year ago

Why q = Q() then q = q | Q(address__city__icontains=city)?

thebjorn Over a year ago

@ammarx because q needs an initial value. It may be clearer if one writes q |= Q(...)? I suppose you could initialize it with the first item in the list q = Q(address__city__icontains=citi_list[0]) and then iterate over city_list[1:] -- but then you need to add back the if statement (instead of letting the for-loop skip the empty list).

Ammar Alyousfi Over a year ago

You can use results.filter(Q(address__city__icontains=city) | Q(another_filter)) as specified here

dease Over a year ago

@ammarx I've checked and you can use (in my case): q = Entry.objects.empty() :)

|

Jose Cherian · Accepted Answer · 2017-11-12 07:46:32Z

0

If you are using at least Django 1.11, this is a one liner.

final_results = result_elms[0].union(*result_elms[1:])

here is the link to documentaion. You may refer to my blog post for more examples.

answered Nov 12, 2017 at 7:46

Jose Cherian

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Comments

christian80gabi · Accepted Answer · 2023-04-12 10:50:02Z

0

If you are using at least Django 3.2, this looks like

>>> qs1 = Author.objects.values_list('name')
>>> qs2 = Entry.objects.values_list('headline')
>>> qs1.union(qs2).order_by('name')

here is the link to documentation.

answered Apr 12, 2023 at 10:50

christian80gabi

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