I think I jumped the gun a bit this morning with my excitement.
The results are wrong in that they return all of the identifiers in my
names table.
species_sentences_secondary = sentences_table.join(entities_table,
and_(sentences_table.c.sentence_id == entities_table.c.sentence_id,
entities_table.c.deleted == 0 ))
print dir(species_sentences_secondary), species_sentences_secondary.c
mapper(Zone, zones_table, properties={ "species":relation(Taxa,
primaryjoin=zones_table.c.zone_id ==
species_sentences_secondary.c.sentences_zone_id,
secondary=entities_species_normalised_table,
viewonly=True
)
is my mapper ...... ( I m sorry the naming has changed but I've been
updating my code from toy code to real app code)
a Zone has many sentences a Sentence has many entities (some of these
entities are normalised and has one row in
entities_species_normalised, which links to one Taxa)
I want to get a list of species mentioned in that Zone...........but I
just can't get it right............I have tried everything I can think
of, but I just can't see the final step to finish it off.
Many thanks in advance
Nathan
2009/5/20 Nathan Harmston <iwanttobeabad...@googlemail.com>:
> The problem was solved by using a join query and then specifying both
> foreign keys and the secondary argument to the relation.
>
> Many thanks,
>
> Nathan
>
>
> secondary = sentences_table.join(tag_table.join(processed_tags_table,
> processed_tags_table.c.tag_id == tag_table.c.tag_id),
> sentences_table.c.sentence_id ==
> tag_table.c.sentence_id)
>
> mapper(Zone, zones_table, properties={
> "species":relation(Name,
>
> primaryjoin=zones_table.c.zone_id == secondary.c.sentences_zone_id,
>
> foreign_keys = [ secondary.c.sentences_zone_id, names_table.c.name_id
> ],
>
> secondary=processed_tags_normalised_table,
> viewonly=True)
>
>
> 2009/5/19 Michael Bayer <mike...@zzzcomputing.com>:
>>
>>
>> On May 18, 2009, at 8:06 PM, Michael Bayer wrote:
>>
>>>
>>> if you want to make a chained join like that, use just primaryjoin(),
>>> dont use "secondary", and set viewonly=True.
>>
>> I might be off on the "dont use secondary" advice. if you do use
>> "secondary", "secondary" is the "middle" table, so in this case it
>> seems like it would be "tags_table" and the target would be
>> "processed_tag_table".
>>
>>> As an alternative to the above approach, you can also try using
>>> traditional relations between each class and use the association proxy
>>> to simplify access from one end to the other.
>>
>> this advice stlll holds though (as does use viewonly=True).
>>
>>
>> >>
>>
>
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To post to this group, send email to sqlalchemy@googlegroups.com
To unsubscribe from this group, send email to
sqlalchemy+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/sqlalchemy?hl=en
-~----------~----~----~----~------~----~------~--~---
