Thanks for that... I didn't manage to get it to work straight off, but
it seems like I'm close.
Tried a couple things just to force it to behave as I wanted.
# defined the selectable
selectable = select( [ sql.column( 'x' ), sql.column('y')],
from_obj =
[ func.foo_props(bindparam( 'x' )) ] ,
bind=...
).alias( 't')
# mapping
mapper( FooProps , selectable , primary_key = [ selectable.c.x ] )
this fails with:
InvalidRequestError: Could not find any Table objects in mapped table
'SELECT x,y FROM foo_props(%(param_1)s)'
#in sqlalchemy.orm.mapper the find_tables() call defaults to
include_aliases = False, forced it to be true:
def _configure_pks(self):
self.tables =
sqlutil.find_tables(self.mapped_table,include_aliases=True)
(include_selectable = True worked also)
then define the relationship:
mapper( Foo , foo_table, properties = dict( props =
relation( FooProps,
primaryjoin = foo_table.c.x = selectable.c.x, foreignkey =
[ selectable.c.x ] )))
So now when I invoke the relationship
a.foo
there a call:
SELECT t.x, t.y
FROM (SELECT x,y
FROM foo_props(%(x)s)) AS t
WHERE %(param_1)s = t.x
but only the param_1 is defined in the parameters to the call. I can
hack it by just setting the initial bindparam('x') to be
bindparam('param1'),
but that's not really ideal obviously
SELECT t.x, t.y
FROM (SELECT x,y
FROM foo_props(%(param_1)s)) AS t
WHERE %(param_1)s = t.x
so what I'm wondering is how to get that 'x' value taken from my
instance a (a.x, in other words) and supplied as a parameter to the
query in a safer way.
eg. relationship( ..., extra_params( x=Foo.c.x ) )
Or from the other direction maybe a way of specifying the bindparam
key for the relationship foreignkey value itself ( and then specify it
to match the bindparam argument ).
eg. relationship( ..., foreign_keys = dict( x= selectable.c.x ))
though not sure how that'd work for compound fks.
Probably just missing something obvious...
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