python - How to filter on calculated column of a query and meanwhile preserve mapped entities -


i have query selects entity , calculated fields 

q = session.query(recipe,func.avg(recipe.somefield).join(.....)

i use select in way assumes can subscript result "recipe" string:

for entry in q.all():    recipe=entry.recipe # access keyedtuple recipe attribute    ...

now need wrap query in additional select, filter calculated field avg:

q=q.subquery();  q=session.query(q).filter(q.c.avg_1 > 1)

and cannot access entry.recipe anymore! there way make sqlalchemy adapt query enclosing one, aliased(adapt_on_names=true) orselect_from_entity()`? tried using given error

as michael bayer mentioned in relevant google group thread, such adaptation done via query.from_self() method. problem in case didn't know how refer column want filter on

this due fact, calculated i.e. there no table refer to!

i might resort using literals(.filter('avg_1>10')), 'd prefer stay in more orm-style

so, came - explicit column expression

row_number_column = func.row_number().over(     partition_by=recipe.id ).label('row_number')  query = query.add_column(     row_number_column ) query = query.from_self().filter(row_number_column == 1)

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