Re: Challenging relationship: many-to-many, custom join, mapped dictionary, can it work???

On May 15, 2008, at 11:23 AM, Allen Bierbaum wrote:

> # ---- WOULD LIKE --------- #
> # Can this be done using
> # - Custom join condition on input_output_type
> # - column_mapped_collection
> #

it can be done.  Try working first with two separate relation()s using  
a secondary join that filters on "input" or "output" (theres an  
example of something similar in the docs); then add  
column_mapped_collection in.

Alternatively, use just one relation, and build dict-like proxies on  
top of it (i.e. class descriptors which return a custom object that  
has a __getitem__ method, which then reads back to the main relation  
to get data).  This the more manual route but is not terribly  
complex.  A not quite the same thing example of this can be seen at: 
http://www.sqlalchemy.org/trac/browser/sqlalchemy/trunk/examples/dynamic_dict/dynamic_dict.py 
  .

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