Hi,
I am currently trying to make a relation between Document and Author, where
there is a many to many association which is dealt with by a secondary table
and I am trying to store the position of an author in the author list.
mapper(Paper, document_table, properties={'journal':relation(Journal,
backref='paper'),
'authors':relation(Author,
secondary=papers_to_authors_table,
collection_class=ordering_list('position'),
order_by=[papers_to_authors_table.c.position]),
'keywords':relation(Keyword,
secondary=documents_to_keywords_table)
})
papers_to_authors_table = Table('p2a_association', metadata,
Column('document', Integer,
ForeignKey('documents.document_id')),
Column('author', Integer,
ForeignKey('authors.author_id')),
Column('position', Integer)
)
However when I try to do this:
File "Worker.py", line 281, in <module>
p = Paper(title, date, authors, journal, j_volume, j_issue, keywords,
abstract, None, body, pmid, institution)
File
"/cluster/soft/Linux_2.6_64/lib/python2.5/site-packages/SQLAlchemy-0.4.8-py2.5.egg/sqlalchemy/orm/attributes.py",
line 1218, in init
oldinit(instance, *args, **kwargs)
File "/cluster/home/nathan/work/workspace/txtmining/Registry.py", line
258, in __init__
self.authors.append(a)
File
"/cluster/soft/Linux_2.6_64/lib/python2.5/site-packages/SQLAlchemy-0.4.8-py2.5.egg/sqlalchemy/orm/collections.py",
line 922, in append
fn(self, item)
File
"/cluster/soft/Linux_2.6_64/lib/python2.5/site-packages/SQLAlchemy-0.4.8-py2.5.egg/sqlalchemy/ext/orderinglist.py",
line 214, in append
self._order_entity(len(self) - 1, entity, self.reorder_on_append)
File
"/cluster/soft/Linux_2.6_64/lib/python2.5/site-packages/SQLAlchemy-0.4.8-py2.5.egg/sqlalchemy/ext/orderinglist.py",
line 202, in _order_entity
have = self._get_order_value(entity)
File
"/cluster/soft/Linux_2.6_64/lib/python2.5/site-packages/SQLAlchemy-0.4.8-py2.5.egg/sqlalchemy/ext/orderinglist.py",
line 189, in _get_order_value
return getattr(entity, self.ordering_attr)
AttributeError: 'Author' object has no attribute 'position'
So is there an easy way of performing this functionality using the ordered
list or do I need to do something else?
Many thanks in advance
nathan
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