Tell me more ×
Stack Overflow is a question and answer site for professional and enthusiast programmers. It's 100% free, no registration required.
up vote 0 down vote favorite

I have these 2 queries :

gifts = Products.objects \
    .filter(entry_query,in_stock__icontains='A-in') \
    .filter(~Q(title__icontains='Not Found'))

and

gifts1 = Products.objects \
    .filter(('city__name__iregex', 'Delhi'),in_stock__icontains='A-in') \
    .filter(~Q(title__icontains='Not Found'))

If I do gifts = gifts | gifts1 I get the following error:

error user-defined function raised exception

If i use Q objects like this:

gifts = Products.objects \
    .filter((Q(entry_query) & Q(in_stock__icontains='A-in')) | Q(('city__name__iregex', 'Delhi'),in_stock__icontains='A-in') ) \
    .filter(~Q(title__icontains = 'Not Found'))

I again get the same error

Here entry query is 

(OR: ('title__iregex', u'bag'), ('description__iregex', u'bag'),('source_website_url__iregex', u'bag'))

Can someone please tell me where am I going wrong

share|improve this question

2 Answers

up vote 0 down vote accepted

The error in the first approach is because gifts1 and gifts are already QuerySets (try typeof(gifts)), so you cannot use | between them. It is like if you were using 'hi'|'goodbye'. You only use | for Q objects.

What you did the second time was almost correct, except the syntax: use | for OR and & for AND. The comma does not provide any logical operation on the Q, leading to a different argument on the filter, leading to an error.

Notice that both using & and joining filters are equivalent in Django (or are supposed to be), but your first approach of getting gift and gift1 as different QuerySets and evaluating them is different: that approach leads to two accesses (hits) to the database, while joining filters or Q objects in a single filter only hits it once.

As a rule of thumb, you should minimize the number of hits to the db.

Hope this helps

share|improve this answer
hey..thanx a lot..that cleared many things – Chaitanya Agarwal Jun 5 at 6:32
up vote 0 down vote

The problem is here:

.filter((Q(entry_query) & Q(in_stock__icontains='A-in')) | Q(('city__name__iregex', 'Delhi'),in_stock__icontains='A-in') ) \

Update it to:

.filter((Q(entry_query) & Q(in_stock__icontains='A-in')) | (Q('city__name__iregex', 'Delhi') &Q(in_stock__icontains='A-in')) ) \
share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.