On Jun 5, 2008, at 11:42 AM, Tomer wrote:
>
> Worked like magic!! Thanks!
>
> BTW, why wasn't SQLA able to determine this automatically like it
> usually does?
when you join PersistentImage->PersistentImage, theres two ways to
join on foreign keys between those (remember that a PersistentImage is
also an Image). So SQLA reports that this is ambiguous.
>
>
> On Jun 5, 11:30 am, Michael Bayer <[EMAIL PROTECTED]> wrote:
>> On Jun 5, 2008, at 11:18 AM, Tomer wrote:
>>
>>
>>
>>
>>
>>> Hi,
>>
>>> I have two tables: Image and PersistentImage, where the latter
>>> inherits the former. In addition, PersistentImage has a foreign
>>> key to
>>> itself (ie, all PersistentImage objects form a hierarchy among
>>> themselves). I haven't been able to get this to work - first it
>>> complained about wanting a primaryjoin, then it seemed to get
>>> confused
>>> between the parent/children relation among PersistentImage objects
>>> and
>>> the inheritance between PersistentImage and Image. Here are my
>>> mappers:
>>
>>> mapper(
>>> Image,
>>> imageTable,
>>> polymorphic_on=imageTable.c.type,
>>> polymorphic_identity='Image'
>>> )
>>
>>> mapper(
>>> PersistentImage,
>>> persistentImageTable,
>>> inherits=Image,
>>> polymorphic_identity='PersistentImage',
>>> properties={
>>> 'children': relation(PersistentImage, backref='parent')
>>> })
>>
>>> And here are the actual table definitions:
>>
>>> imageTable = Table('Images', metadata,
>>> Column('id', Integer, primary_key=True),
>>> Column('name', String(256), nullable=False),
>>> Column('type', String(30), nullable=False)
>>> )
>>
>>> persistentImageTable = Table('PersistentImages', metadata,
>>> Column('id', Integer, ForeignKey('Images.id'), primary_key=True),
>>> Column('parentId', Integer, ForeignKey('PersistentImages.id')),
>>> Column('userId', Integer, ForeignKey('Users.id'), nullable=False)
>>> )
>>
>> here it is:
>>
>> mapper(PersistentImage, persistentImageTable, inherits=Image,
>> inherit_condition=persistentImageTable.c.id==imageTable.c.id,
>> polymorphic_identity='PersistentImage',
>> properties={
>> 'children':relation(PersistentImage,
>> primaryjoin
>> =persistentImageTable.c.parentId==persistentImageTable.c.id,
>> backref=backref('parent',
>> primaryjoin
>> =persistentImageTable.c.parentId==persistentImageTable.c.id,
>> remote_side=[persistentImageTable.c.id])
>> )
>> })
>>
>> SQLA would probably slightly happier if you had the "parentId"
>> foreign
>> key referencing Images.id instead of PersistentImages.id but this
>> should not be required.
> >
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