This started occurring just after the qs-rf branch was merged into trunk.
Essentially, my Connection models has two separate FKs to the Port model (called start and end), the Port model has a FK to the device model, and the Device model has a FK to the building model.
When I want to get a list of all connections that start and end in the same building, I do the following:
Connection.objects.filter(start__device__building=building_name, end__device__building=building_name)
This works correctly for the most part. However, if I add .select_related() onto the end of the line, it all goes wrong. The following is the output from runtest.py in the attachment, which should show the problem:
>>> from test import runtest
Begin list of normal filter
10 FROM router/4 TO switch/7
11 FROM switch/7 TO server/1
(end list)
Begin list of filter using select_related
10 FROM switch/4 TO switch/7
11 FROM server/7 TO server/1
(end list)
As you can see, in the first list, the start of the first connection is device "router", port 4 and the end is device "switch", port 7. When the exact same query is done with select_related on the end, the port numbers are the same, but the start device has for some reason been changed to be equal to the end device. From what I read in the documentation, select_related should not affect the output at all, so I believe this must be a bug.
Attached is my whole test app where you can see for yourself what is happening.
