CODEWITHSUNDEEP
djangodjango-queryset
Feanor
Feanor

Reputation: 3690

django optimize merging querysets

For example, I have 2 querysets:

q1=MyModel.objects.filter(visible=True)
q2=MyModel.objects.filter(published=True)

And i need to make single queryset or list having all objects from q1 and q2.

I used to do it like this:

q=list(chain(q1,q2))
#q= q1 | q2 #this gives me not all objects from q2 or q1,so i don't use bitwise or

But it was said, that list() will produce extra queries to database. Is it true? And if it is, can somebody specify the most optimized way to do the merge?

Upvotes: 0

Views: 295

Answers (2)

marianobianchi
marianobianchi

Reputation: 8488

You can try to do this:

q1_pks = MyModel.objects.filter(visible=True).values_list('pk', flat=True)
q2_pks = MyModel.objects.filter(published=True).values_list('pk', flat=True)

final_query = MyModel.objects.filter(pk__in=list(q1_pks).extend(list(q2_pks)))

That should do the trick, although i'm not sure if those list(qX_pks) produce performances issues or not.

Upvotes: 1

catherine
catherine

Reputation: 22808

q1=MyModel.objects.filter(visible=True)
q2=MyModel.objects.filter(published=True)
qs12 = QuerySetSequence(qs1, qs2)

Combine the above code with this snippet: http://djangosnippets.org/snippets/1933/

Upvotes: 1

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