CODEWITHSUNDEEP
djangopagination
vijay shanker
vijay shanker

Reputation: 2663

Concatenate queryset in django

I want to concatenate two queryset obtained from two different models and i can do it using itertools like this:

ci = ContributorImage.objects.all()
pf = Portfolio.objects.all()
cpf = itertools.chain(ci,pf)

But the real fix is paginating results.If i pass a iterator(cpf, or our concatenated queryset) to Paginator function, p = Paginator(cpf, 10), it works as well but fails at retrieving first page page1 = p.page(1) with an error which says:

TypeError: object of type 'itertools.chain' has no len()

What can i do in case like this ?

Upvotes: 0

Views: 1002

Answers (2)

Ali
Ali

Reputation: 2591

I know it's too late, but because I encountered this error, I would answer to this question.

you should return a list of objects:

ci = ContributorImage.objects.all()
pf = Portfolio.objects.all()
cpf = itertools.chain(ci,pf)

cpf_list = list(cpf)

Upvotes: 0

Serafeim
Serafeim

Reputation: 15084

The itertools.chain() will return a generator. The Paginator class needs an object implementing __len__ (generators, of course do not support it since the size of the collection is not known).

Your problem could be resolved in a number of ways (including using list to evaluate the generator as you mention) however I recommending taking a look at the QuerySetChain mentioned in this answer:

https://stackoverflow.com/a/432666/119071

I think it fits exactly to your problem. Also take a look at the comments of that answer - they are really enlightening :)

Upvotes: 1

Related Questions