Now that I've got the ActiveMapper code working to my satisfaction,
I'm trying to add inheritance. This is proving to be no small task.
At the moment, I'm modelling things as follows:
class A(ActiveMapper):
class mapping:
a_id= column( Integer, primary_key=True )
a_field= column( Unicode(40) )
class B(A):
class mapping:
b_id= column( Integer, foreign_key="a.a_id", primary_key=True )
b_field= column( Unicode(40) )
(Note: these are totally fictitious classes. I'm actually working on
an Identity provider for TurboGears.)
In the __init__ method for the ActiveMapperMeta class, I check to
determine whether the class inherits from another class with a mapper
and if so, the new mapper is created using the inherits keyword
argument. This seems to work just fine when I'm creating new objects,
however, retrieving those objects seems problematic.
Let's say I want to retrieve a B; I use the following code:
b= B.get(1)
Instead of my glorious B, I get:
Traceback (most recent call last):
File "<console>", line 1, in ?
File "/Users/jeff/Projects/Web/sqlalchemy/lib/sqlalchemy/mapping/
mapper.py", line 272, in get
return self._get(key, ident)
File "/Users/jeff/Projects/Web/sqlalchemy/lib/sqlalchemy/mapping/
mapper.py", line 286, in _get
params["pk_"+primary_key.key] = ident[i]
IndexError: tuple index out of range
So I ask, "what gives?" Everything works fine if I execute:
b= B.select()[0]
But that's not very helpful.
--
Jeff Watkins
http://newburyportion.com/
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