this is a many-to-one self-referential relationship. the
"remote_side" attribute is needed on both relations() to establish
this, and the uselist=False is not needed (its hiding the actual error
here). See the docs on "self-referential mappings".
On May 28, 2008, at 6:11 PM, kremlan wrote:
>
> My goal is to have a one-to-one relation defined using the same name
> as the foreign key column underneath. I have 'contacts' table with
> 'created_by' and 'updated_by' columns which are FKs to contacts.id.
>
> contacts = Table('contacts', meta,
> Column('id', Integer, primary_key=True),
> Column('first_name', String(25)),
> Column('middle_name', String(25)),
> Column('last_name', String(25)),
> # etc...
> Column('created_at', DateTime),
> Column('updated_at', DateTime),
> Column('created_by', Integer),
> Column('updated_by', Integer),
> ForeignKeyConstraint(['created_by'], ['contacts.id']),
> ForeignKeyConstraint(['updated_by'], ['contacts.id'])
> )
>
>
> mapper(Contact, contacts, properties={
> '_created_by': contacts.c.created_by,
> '_updated_by': contacts.c.updated_by,
> 'created_by': relation(Contact,
> primaryjoin=contacts.c.created_by==contacts.c.id, uselist=False),
> 'updated_by': relation(Contact,
> primaryjoin=contacts.c.updated_by==contacts.c.id, uselist=False),
> })
>
> The primaryjoin is necessary due to the multiple FKs back to contacts.
>
> This follows the pattern suggested here:
> http://groups.google.pl/group/sqlalchemy/browse_thread/thread/e20bb32241ced699
>
> No errors occur but the 'created_by' column in the table is not
> actually updated upon flush/commit. Instead the _created_by attribute
> is updated.
>
>
> >
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