Jonathan Vanasco <jonat...@findmeon.com> writes:
> in postgresql i have a boolean field that allows Null values.
>
> i'd like to query for the items that are not 'true'
>
> filter( tablename.is_deleted != True )
>
> creates this sql:
> is_deleted != True
>
> however this is incorrect and doesn't match the resultset i want. it
To be fair, it is correct in terms of doing what you asked, though if
you want it to include NULLs I agree it doesn't do what you want...
> needs to read :
> is_deleted IS NOT True
There are "is" and "isnot" operators in sqlalchemy.sql.operators, but I'm
not entirely sure how to trigger from within an expression (and they don't
seem to be column operators, but I'm probably missing something simple).
However, you should be able to use the generic "op" method, as in:
filter(tablename.is_deleted.op("IS NOT")(True))
Alternatively, you could explicitly manage the handling of NULL
entries:
from sqlalchemy.sql.functions import coalesce
filter(coalesce(tablename.is_deleted, False) != True)
This way you avoid the treatment of NULLs in the comparison entirely. This
method also extrapolates to other cases more readily since it works with
non-boolean fields as well.
-- David
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