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


Question

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)

1
26
12/9/2015 7:12:52 PM

Accepted Answer

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) 
    ')
6
10/22/2010 5:02:07 PM

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)))

Licensed under: CC-BY-SA with attribution
Not affiliated with: Stack Overflow
Icon