Very odd behaviour when merging multiple SearchQuerySets with the pipe operator

[Salvatore Iovene]

Hi,

I have multiple search index, and a complex search form. According to the user selection in the search form, I apply filters to my search indexes.

At the end, I merge the results with the pipe operator.

I found that I can make a search that results in empty results in each individual SearchQuerySet for each individual search index, but when I merge them, the result is the complete set of my indexed objects.

Easy to see it in the following pdb session:

> /var/www/astrobin/astrobin/forms.py(567)search()

-> print "len(sqs) = %d" % len(sqs)

(Pdb)

len(sqs) = 0

> /var/www/astrobin/astrobin/forms.py(568)search()

-> print "len(user_sqs) = %d" % len(user_sqs)

(Pdb)

len(user_sqs) = 0

> /var/www/astrobin/astrobin/forms.py(569)search()

-> print "len(image_sqs) = %d" % len(user_sqs)

(Pdb)

len(image_sqs) = 0

> /var/www/astrobin/astrobin/forms.py(570)search()

-> print "len(gear_sqs) = %d" % len(user_sqs)

(Pdb)

len(gear_sqs) = 0

> /var/www/astrobin/astrobin/forms.py(572)search()

-> sqs = sqs | user_sqs | image_sqs | gear_sqs

(Pdb)

> /var/www/astrobin/astrobin/forms.py(573)search()

-> print "len(sqs) = %d" % len(sqs)

(Pdb)

len(sqs) = 1

(where 1 is the total number of objects in my Image search index.

So, why did merging the querysets return an object when all of them had no results?

Am I doing something wrong?

I run django-haystack 2.6.1.

Thanks!

Salvatore