On May 17, 2009, at 2:13 PM, Nathan Harmston wrote:
>
> Hmm....I tried it again with echo=debug and some output but it seems
> that my query returns no results (although when I try it on its own it
> returns the right ones). When I try to just use it with only one name
> in bar_table, it works perfectly but with multiple names it doesnt
> work. Can column_property handle this kind of thing? or should I be
> looking for something else?
do you mean multiple rows in bar_table with the same foo_id? no, that
wont work, your database should actually be raising an error. For a
one-to-many relationship you'll have to map bar_table in a class and
link to it via relation().
>
>
> foo_table = Table("foo", metadata,
> Column("foo_id", Integer, primary_key=True),
> Column("data", Text, nullable=False)
> )
>
> bar_table = Table("bar", metadata,
> Column("bar_id", Integer, primary_key=True),
> Column("foo_id", Integer, ForeignKey("foo.foo_id")),
> Column("name", Text)
> )
>
> class Foo(object):
> pass
>
> mapper(Foo, foo_table, properties={ "names" :
> column_property(select([bar_table.c.name], foo_table.c.foo_id ==
> bar_table.c.foo_id).label("names")) } )
>
> session = Session()
> for i in session.query(Foo):
> print i, i.names
>
> 2009-05-17 19:06:42,031 INFO sqlalchemy.engine.base.Engine.0x...2e70
> BEGIN
> 2009-05-17 19:06:42,033 INFO sqlalchemy.engine.base.Engine.0x...2e70
> SELECT (SELECT bar.name
> FROM bar
> WHERE foo.foo_id = bar.foo_id) AS names, foo.foo_id AS foo_foo_id,
> foo.data AS foo_data
> FROM foo
> 2009-05-17 19:06:42,033 INFO sqlalchemy.engine.base.Engine.0x...2e70
> []
>
> Many thanks again,
>
> Nathan
>
>
> 2009/5/15 Michael Bayer <[email protected]>:
>>
>> put echo='debug' to see what the results are.
>>
>> On May 15, 2009, at 8:08 AM, Nathan Harmston wrote:
>>
>>>
>>> Hi,
>>>
>>> I am trying to use a column property, I have a class Foo:
>>>
>>> class Foo(object):
>>> pass
>>>
>>> which is mapped to a table foo_table and it has multiple names which
>>> are stored in bar_table with foo_id as the primary key in Foo and
>>> ForeignKey in bar_table.
>>>
>>> I am trying to use a column property to access these:
>>>
>>> mapper(Foo, foo_table, properties={ "names" :
>>> column_property(select([bar_table.c.name], bar_table.c.foo_id ==
>>> foo_table.c.foo_id).label("names")) } )
>>>
>>> so when I try to query any of the objects I just get no results
>>> back,
>>> but when I try it without the column property I get something back.
>>>
>>> Am I just doing something incredibly stupid wrong?
>>>
>>> Many thanks in advance,
>>>
>>> Nathan
>>>
>>>>
>>
>>
>>>
>>
>
> >
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