Silly django confusion

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:

SELECT * FROM app_table;
    => 3 rows of data

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:

from django.db import models

from app.models import SuperTable

class Table(SuperTable):
    field1 = models.CharField(max_lenth=200)

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.

1.3 KiB Raw Blame History

Silly django confusion

1.3 KiB

Raw Blame History