Re: [Sqlalchemy-users] many to many question on select_by

Wed, 28 Jun 2006 10:21:15 -0700

dennis -

im not getting these results.  can you attach a more complete test program ?

my result for the query in question is:

s.query(Drawing).select_by(name='test')

SELECT drawings.id AS drawings_id
FROM tags, drawings, drawing_tags
WHERE tags.name = ? AND (drawings.id = drawing_tags.drawing_id AND tags.id = drawing_tags.tag_id) ORDER BY drawings.oid

which is the correct query (and also no endless loop....but of course thats a bug id like to see how youre getting it to do that)

On Jun 28, 2006, at 12:20 PM, Dennis Muhlestein wrote:



On 6/28/06, Dennis Muhlestein <[EMAIL PROTECTED]> wrote:
I've set up a simple many-to-many relation almost exactly as the 0.2.4 docs specify for using a secondary table:


drawing=Table( Column('id', <SNIP all the columns /> )
tags=Table ( 'tags', engine,
                Column ( 'id', Integer, primary_key=True,nullable=False ),
                Column ( 'name', VARCHAR(20), nullable=False,index='ix_tags_name' ) )
                
drawing_tags = Table ( 'drawing_tags', engine,
                Column ( 'drawing_id', Integer, ForeignKey(' drawings.id'),primary_key=True,nullable=False ),
                Column ( 'tag_id', Integer, ForeignKey(' tags.id'), primary_key=True,nullable=False ) )

class Tag(object):
    pass
class Drawing(object):
    pass
mapper(Drawing,drawing,
    properties={
        'tags':relation(Tag,secondary=drawing_tags)
    }
    )    
mapper(Tag,tags,properties={'drawings':relation(Drawing,secondary=drawing_tags)})

The following works:

d=s.query(Drawing).get( <whatever_id> )
d.tags
[ the, list, of, tags ]

The following also works
t=s.query(Tag).get( <whatever_id> )
t.drawings
[ the, list, of, drawings ]

The last one here doesn't quite work though:
d=s.query(Drawing).select_by( name == <whatever tag name> )

for name I've tried name, tag_name and a few others.  the query can't resolve those properties. The docs were a little unclear as to whether we needed = or == for the operator so I tried both but neither worked.
The only thing that worked was to use tags.c.name == <whatever_id> but then the query is as follows:

SELECT drawings.id, <snipped columns />
        FROM tags, drawings
        WHERE tags.name = <whatever_name> ORDER BY drawings.id

Notice that the from clause isn't doing the join on drawing_tags.  The resulting data set contains all the drawings instead of the joined drawings on the association table.

So, am I missing something here?  Has a bug been introduced or am I doing something wrong.

Thanks
Dennis



An added Note:
if I do s.query(Drawing).select_by(name='test') I get:

  File "build/bdist.linux-i686/egg/sqlalchemy/orm/query.py", line 128, in search_for_prop
  File "build/bdist.linux-i686/egg/sqlalchemy/orm/query.py", line 128, in search_for_prop
  File "build/bdist.linux-i686/egg/sqlalchemy/orm/query.py", line 128, in search_for_prop
  File "build/bdist.linux-i686/egg/sqlalchemy/orm/query.py", line 128, in search_for_prop
  File "build/bdist.linux-i686/egg/sqlalchemy/orm/query.py", line 119, in search_for_prop
  File "build/bdist.linux-i686/egg/sqlalchemy/orm/mapper.py", line 166, in _get_props
RuntimeError: maximum recursion depth exceeded

Thoughts, I'm sure I've missed some dumb little detail somwhere.

-Dennis
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