CODEWITHSUNDEEP
djangodjango-queryset
Jasmine Rain
Jasmine Rain

Reputation: 449

How to concatenate QuerySets from a list of QuerySet

I come across this syntax on stackoverflow

from itertools import chain 
result_list = list(chain(page_list, article_list, post_list))

I need to concatenate a bunch of QuerySets with something like this:

    prjExpList = list(chain(lvl for lvl in prjlvl))
    prjEnvList = list(chain(env for env in prjEnv))

This gives me an error of 

AttributeError: 'QuerySet' object has no attribute '_meta'

My goal is to concatenate a bunch of QuerySets that's stored inside a list prjlvl and prjEnv How do I do that?

Upvotes: 1

Views: 1121

Answers (2)

Kye
Kye

Reputation: 4495

Are the QuerySets of the same model? You can just do

combined_queryset = queryset_1 | queryset_2 | queryset_3

To chain them together into one QuerySet. This means you can still do things with the QuerySet in the ORM, which is a big help.

Upvotes: 2

Frank T
Frank T

Reputation: 9046

Try:

prjExpList = list(chain.from_iterable(prjlvl))

Note that itertools.chain() takes a *args list of iterables, and that you can get the same unpacking behavior from the chain.from_iterable() class method.

See: https://docs.python.org/2/library/itertools.html#itertools.chain

Upvotes: -1

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