Michael Bayer wrote:
> On Apr 27, 2007, at 11:17 AM, Dave Harrison wrote:
>> Hi all,
>>
>> I've got a situation where I have a table of data that is common,
>> with the
>> subtables just adding an extra couple of fields. Using multiple
>> inheritance I
>> fit it together as below (pretty much the same as the documented
>> example).
>>
>> What I'm having problems with is then accessing those child tables
>> as properties
>> of the person table mapping. I'm get the following error,
>>
>> """
>> Cant determine relation direction for 'example' on mapper 'Mapper|
>> Person|person'
>> with primary join 'person.id = example.person_id' - foreign key
>> columns are not
>> present in neither the parent nor the child's mapped
>> tablesset([Column('person_id',Integer(),ForeignKey('person.id'))])
>> """
>>
>>
>
> the surprise here is that you established the relationship to the
> subclass, when the join condition is expressed in the superclass'
> table. theres all kinds of logic that is "limiting" the search for
> joins and foreign key relationships to between just the "local"
> tables (i.e. not to the joined inherited/inheriting tables) since we
> have a lot of test cases with very intricate self-referential
> relationships that blow up easily. so this innocent example led to
> the need to make all those searches look in both places separately
> and pick the one that fits better. this is in r2564.
>
>> P.S that error should read "foreign key columns are present in
>> neither ..."
>
> also in r2564.
Thanks Michael, much appreciated. By the way, congratulations on a fantastic
project.
Cheers
Dave
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