Django query filter combining AND and OR with Q objects don't return the expected results

问题

I try to combine AND and OR in a filter using Q objects. It looks like that the | behave like an AND. This is related to the previous annotate which is run in the same query and not as a subquery.

What is the correct way to handle this with Django?

models.py

class Type(models.Model):
    name = models.CharField(_('name'), max_length=100)
    stock = models.BooleanField(_('in stock'), default=True)
    hide = models.BooleanField(_('hide'), default=False)
    deleted = models.BooleanField(_('deleted'), default=False)

class Item(models.Model):
    barcode = models.CharField(_('barcode'), max_length=100, blank=True)
    quantity = models.IntegerField(_('quantity'), default=1)
    type = models.ForeignKey('Type', related_name='items', verbose_name=_('type'))

views.py

def hire(request):
    categories_list = Category.objects.all().order_by('sorting')
    types_list = Type.objects.annotate(quantity=Sum('items__quantity')).filter(
        Q(hide=False) & Q(deleted=False),
        Q(stock=False) | Q(quantity__gte=1))
    return render_to_response('equipment/hire.html', {
           'categories_list': categories_list,
           'types_list': types_list,
           }, context_instance=RequestContext(request))

resulting SQL query

SELECT "equipment_type"."id" [...] FROM "equipment_type" LEFT OUTER JOIN
    "equipment_subcategory" ON ("equipment_type"."subcategory_id" =
    "equipment_subcategory"."id") LEFT OUTER JOIN "equipment_item" ON
    ("equipment_type"."id" = "equipment_item"."type_id") WHERE 
    ("equipment_type"."hide" = False AND "equipment_type"."deleted" = False )
    AND ("equipment_type"."stock" = False )) GROUP BY "equipment_type"."id"
    [...] HAVING SUM("equipment_item"."quantity") >= 1

expected SQL query

SELECT
    *
FROM
    equipment_type
LEFT JOIN (
    SELECT type_id, SUM(quantity) AS qty
    FROM equipment_item
    GROUP BY type_id
) T1
ON id = T1.type_id
WHERE hide=0 AND deleted=0 AND (T1.qty > 0 OR stock=0)

EDIT: I added the expected SQL query (without the join on equipment_subcategory)

回答1:

Try adding parentheses to explicitly specify your grouping? As you already figured out, multiple params to filter() are just joined via AND in the underlying SQL.

Originally you had this for the filter:

[...].filter(
    Q(hide=False) & Q(deleted=False),
    Q(stock=False) | Q(quantity__gte=1))

If you wanted (A & B) & (C | D) then this should work:

[...].filter(
    Q(hide=False) & Q(deleted=False) &
    (Q(stock=False) | Q(quantity__gte=1)))

回答2:

This answer is late but could be helpful to a lot of guys out there.

[...].filter(hide=False & deleted=False)
.filter(Q(stock=False) | Q(quantity__gte=1))

This will generate something similar to

WHERE (hide=0 AND deleted=0 AND (T1.qty > 0 OR stock=0))

回答3:

OK, no success here or on #django. So I choose to use a raw SQL query to solve this problem...

Here the working code:

types_list = Type.objects.raw('SELECT * FROM equipment_type
    LEFT JOIN (                                            
        SELECT type_id, SUM(quantity) AS qty               
        FROM equipment_item                                
        GROUP BY type_id                                   
    ) T1                                                   
    ON id = T1.type_id                                     
    WHERE hide=0 AND deleted=0 AND (T1.qty > 0 OR stock=0) 
    ')

回答4:

Here's my example of complicated query, I hope you find it helpful

or_condition = Q()
and_condition = Q(company=request.user.profile.company)

for field in MyModel._meta.get_fields():
    if field.name != 'created_on' and field.name != 'company':
        or_condition.add(
            Q(**{"{}__icontains".format(field.name): query}), Q.OR)

and_condition.add(or_condition2, Q.AND)
MyModel.objects.filter(and_condition)

The problem with this method is that you get an empty (AND: ) case in your or_condition. It doesn't affect the query at all, but it annoys me! My current solution is as follows

import operator
from functools import reduce

and_condition = Q(company=request.user.profile.company)
or_condition = reduce(operator.or_, (Q(**{"{}__icontains".format(field.name): query})
                                     for field in MyModel._meta.get_fields() if field.name != 'created_on' and field.name != 'company'))

and_condition.add(or_condition, Q.AND)
MyModel.objects.filter(and_condition)

来源：https://stackoverflow.com/questions/3986071/django-query-filter-combining-and-and-or-with-q-objects-dont-return-the-expecte

标签

python

django

django-q