Working on some code I've hit that the reverse name for a
OneToOneField cannot be used, it seems, in values_list or values. I
couldn't see why there would need to be such an exclusion, given it is
a one-to-one relationship, so am wondering if it's just an oversight
in the code or a deliberate exclusion?
The portion of code that is rejecting doing e.g.
"values_list('onetoonereversename')" is in setup_joins where the if
line reads:
if not allow_many and (m2m or not direct):
The values of "m2m" and "direct" come from opts.get_field_by_name and
it seems that the reverse of a OneToOne gives the same results as the
reverse of a ForeignKey, as of course both are not m2m and are not
direct. Looking at the code later on in setup_joins it describes the
path where direct is false and m2m is false as being "One-to-many
field (ForeignKey defined on the target model)", so it looks like the
logic I've quoted above of "if not allow_many and (m2m or not direct)"
has the "not direct" clause in to reject reverse ForeignKey
relationships and in doing so also rejects reverse OneToOne
relationships (and with the latter case I suspect it need not!).
If someone a bit more knowledgeable about the query machinery could
comment on whether it does look like an oversight or is a deliberate
exclusion, then if it's the former I'll log it as a bug.
Assuming the rest of the code is ok in the case of a reverse OneToOne
then something along the lines of "if not allow_many and (m2m or (not
direct and not isinstance(getattr(field,'field',None),OneToOneField))"
instead could work to allow OneToOne reverses through in setup_joins
when allow_many is False.
Regards,
Matt
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