Django: how to query all values in an array?

Question

I have a checkbox with multiple values. For example, hobbies. When the user choose some hobbies, he wants to see the person who has all those hobbies.

I dont go into details for sake of clarity so here's how I read all the checked values and put them in my "big" query, which is, as you may guess: q:

hobbies2 = [int(l) for l in g.getlist('hobbies2')]
if len(hobbies2):
    q = q & Q(personne__hobbies2__in=hobbies2)

The problem is that it returns all persons who have a hobby in common (i.e. it's like "or", not "and").

How to get all those many to many values with a and?

Soviut · Accepted Answer · 2017-04-21 07:27:26Z

1

The __in operator is for filtering by a set. It is not meant for checking multiple values at once in a many-to-many relationship.

It literally translate to the following in SQL:

SELECT ... WHERE hobbies IN (1, 3, 4);

So you'd need to build your query using AND conditions. You can do this with consecutive filters:

queryset = Personne.objects.all()

# build up the queryset with multiple filters
for hobby in hobbies2:
    queryset = queryset.filter(hobbies2=hobby)

edited Apr 21, 2017 at 7:27

answered Jun 19, 2016 at 18:35

Soviut

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3 Comments

Olivier Pons Over a year ago

Are you sure that personne__hobbies2=hobby will not eliminate people when there's more than one hobby? For example: kayak = 1, ski = 2. This will filter first personne__hobbies2=1 then after personne__hobbies2=1. Are you sure that it may work?

Olivier Pons Over a year ago

With consecutive Q objects doesnt work. I've tried the #1 solution here: stackoverflow.com/questions/8618068/… it doesnt work too.

Soviut Over a year ago

Thanks for the link, I've updated my answer to remove the Q queries. However, the consecutive filters should work since those are demonstrated in the link.

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