Strange behavior with complex Q object filter queries in Django
- by HWM-Rocker
Hi I am trying to write a tagging system for Django, but today I encountered a strange behavior in filter or the Q object (django.db.models.Q).
I wrote a function, that converts a search string into a Q object. The next step would be to filter the TaggedObject with these query. But unfortunately I get a strange behavior.
when I search (id=20) =
Q: (AND: ('tags__tag__id', 20))
and it returns 2 Taged Objects with the ID 1127 and 132
when I search (id=4) =
Q: (AND: ('tags__tag__id', 4))
and it returns also 2 Objects, but this time 1180 and 1127
until here is everything fine, but when i make a little bit more complex query like (id=4) or (id=20) =
Q: (OR: ('tags__tag__id', 4), ('tags__tag__id', 20))
then it returns 4(!) Objects 1180, 1127, 1127, 132
But the object with the ID 1127 is returned twice, but thats not the behaviour I want. Do I have to live with it, and uniqify that list or can I do something different. The representation of the Q object looks fine for me.
But the worst is now, when I search for (id=20) and (id=4) =
Q: (AND: ('tags__tag__id', 20), ('tags__tag__id', 4)) then it returns no object at all. But why? The representation should be ok and the object with the id 1127 is tagged by both. What am I missing?
Here are also the relevant parts of the classes, that are involved:
class TaggedObject(models.Model):
"""
class that represent a tagged object
"""
tags = generic.GenericRelation('ObjectTagBridge',
blank=True, null=True)
class ObjectTagBridge(models.Model):
"""
Help to connect a generic object to a Tag.
"""
# pylint: disable-msg=W0232,R0903
content_type = models.ForeignKey(ContentType)
object_id = models.PositiveIntegerField()
content_object = generic.GenericForeignKey('content_type', 'object_id')
tag = models.ForeignKey('Tag')
class Tag(models.Model):
...
Thanks for your help
