#13073: Duplicate rows when checking ID
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Reporter: jnadro52 | Owner: nobody
Status: new | Milestone:
Component: Database layer (models, ORM) | Version: 1.1
Keywords: | Stage: Unreviewed
Has_patch: 0 |
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Hello:
I hope that this is a legitimate bug and I'm not wasting your time with
something that is a slight misunderstanding of how the Django database
layer works. Here we go...
I have two tables... a table that holds football matchups (texans vs.
giants, for example) and a table that caches the statistics for the game.
The table that caches the statistics would have a row per team, so this is
what the data would look like:
{{{
ID team opponent matchup_id
1 texans giants 1
2 giants texans 1
}}}
So now I want to retrieve these two rows by matchup ID. Lets say the
model names are "matchup" and "cache". So, I attempted to go retrieve
them like so:
{{{
caches = cache.objects.filter(matchup=1)
}}}
When I do so, I do get two objects returned, but they are both the same
cache row that is returned. So I would get a QuerySet containing two
objects, both of which would have the same primary key.
What really confused me is that if I added a .distinct() method call to
the end of that call, I would get the expected results. If it is the case
where there is a join occurring I would understand getting duplicates,
even though I would think there should be no join in this call, since i am
just checking a foreign key. The kicker is that I always get row id 2 and
never row id 1 when I make this call without the distinct call as well.
If this were a cross-join, I should get multiple duplicates of all rows
that meet the criteria, but I do not.
I hope I explained this well enough, please feel free to contact me at my
given email if you have any questions.
--
Ticket URL: <http://code.djangoproject.com/ticket/13073>
Django <http://code.djangoproject.com/>
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