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I'm setting up a testing environment for work, using fixtures to save
and load test data and I got a little stumped by something I ran into.
I had exported one of the database tables we use to a json file that I
was going to import into a fresh new database to test with. When I
imported it everything seemed fine, except when looking at the actual
page. So this is what I found:
[[!format sql """
SELECT * FROM app_table;
=> 3 rows of data
"""]]
[[!format py """
from app.models import Table
Table.objects.count()
=> 3
Table.objects.all()
=> []
"""]]
This is weird. So I looked at the `django.db.connection.queries`
property and I realized that it was doing a join since the model
subclasses another:
[[!format py """
from django.db import models
from app.models import SuperTable
class Table(SuperTable):...
"""]]
Which, of course, means that in order to get the complete `Table`
instance, the related `SuperTable` instance is also required, but in
order to do a `COUNT` of `app_table` it isn't necessary. And that's
where the inconsistency came from, now that I've also copied the
contents of `SuperTable` everything is fine again.
[[!meta date="2012-04-24 15:51:00"]]
[[!tag python django coding]]
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