On Jun 17, 2013, at 08:58 , Chris Withers <[email protected]> wrote:
> Hi All,
>
> I seems to commonly need to do a query which should return zero or one mapped
> objects.
>
> .one() isn't what I want as no returned object is ok.
>
> .first() isn't what I want as if my query would return more than one object,
> I have the query wrong and so want an exception.
>
> Is there something already available that meets this need?
This will requrie you to run a query which limits the result to max 2 rows so
you can check if more than one result would be returned. I would just create a
simple wrapper function:
def one_optional(query):
rows = query.limit(2).all()
count = len(rows)
if count == 0:
return None
elif count == 1:
return rows[0]
else:
raise RuntimeError('More than one result found.')
Wichert.
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