Django queries using a list

Question

I would like to run a query in django using a list. I found a similar post on stack overflow that got me to where I am now, but I can't seem to get my code to work. I think the only difference is that I am using REST. My code below is throwing the error unsupported operand type(s) for &: 'Build' and 'Build'

What I am expecting is that the query will return all entries where the author_id matches any value in the machinesOwned list.

from .models import Build
import operator
from functools import reduce

class buildStatsAPI(generics.ListCreateAPIView):#for build stats
    permission_classes = (permissions.IsAuthenticated,)
    serializer_class = buildStatsAPI_serializer
    def get_queryset(self):
    machinesOwned = [4,5,7,9]
    query = reduce(operator.and_, (Build(author_id= item) for item in [machinesOwned]))
    return Build.objects.filter(query,deleted = 0,).values()

What is Build here? It looks a bit strange that you query with Build(..) & Build(..) etc as a filtering object? Should these be Q objects? — willeM_ Van Onsem
– willeM_ Van Onsem, Commented Feb 3, 2019 at 16:55
Ah yes that is part of my issue I think. However I changed to query = reduce(operator.and_, (Q(author_id= item) for item in [machinesOwned])) and it returns : int() argument must be a string, a bytes-like object or a number, not 'list' — MattG
– MattG, Commented Feb 3, 2019 at 17:00

schillingt · Accepted Answer · 2019-02-03 17:01:28Z

1

You can dynamically create a list of Q objects, but you might be able to do this a bit more efficiently another way:

Build.objects.filter(
    deleted=0,
    author_id__in=machinesOwned,
).values()

Otherwise if you're set on your current approach:

from django.db.models import Q
query = reduce(operator.and_, (Q(author_id= item) for item in machinesOwned))
Build.objects.filter(query,deleted = 0,).values()

answered Feb 3, 2019 at 17:01

schillingt

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1 Comment

MattG Over a year ago

I sure love this community! Thank you for the solution. Your first suggestion is much more efficient, and works as I expected

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