So I have this loop:
for t in ts.prefetch_related('u__v_set'):
bla = t.x
...
Running this code in debugsqlshell I see three (constant amount in general)
sql statements:
- one getting all t's
- second one getting related u's
- third one getting related v's
Now, in the same loop I would like to refer to some attribute of v (that
was the reason I used prefetch_related). If I do it like this:
ble = ','.join([item for item in map(lambda x: x[0],
t.u.all().values_list('v__some_attribute')) if item])
the cash is invalidated and new sql is produced for each iteration of t.
Another try:
ble = ','.join([v.some_attribute for v in reduce(lambda x, y: x|y,
[us.v_set.all() for us in t.u.all()]) if v.some_attribute])
this also invalidates cash. So how can I use this prefetched values at all?
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