Thanks so much for the help. For the record, setting an __init__ argument on
the association argument did the trick.
Ben
On 2 Aug 2011, at 01:47, Michael Bayer <mike...@zzzcomputing.com> wrote:
>
> On Aug 1, 2011, at 8:34 PM, somewhatofftheway wrote:
>
>> Hi,
>>
>> I'm trying to convert a 'simple' many-to-many relationship to an
>> association object in order to allow the relationship to have
>> attributes. I've followed the code in examples/association/
>> proxied_association.py fairly closely (or so I thought) but it isn't
>> working for me.
>>
>> As an example, let's say I am trying to create a relationship between
>> an RSS feed and the pages from the feed but I want a feed_date on the
>> relationship. Currently, my code look something like this:
>>
>> class Page (Base):
>> __tablename__ = 'pages'
>> id = Column(Integer, primary_key=True)
>>
>> posts = relationship("Post", cascade="all, delete-orphan",
>> backref='pages')
>> feeds = association_proxy("feeds", "feed")
>>
>>
>> class Post(Base)
>> __tablename__ = 'pages_feeds'
>> page_id = Column(Integer, ForeignKey('pages.id'),
>> primary_key=True)
>> feed_id = Column(Integer, ForeignKey('feeds.id'),
>> primary_key=True)
>> feed = relationship(Feed, lazy='joined')
>>
>> I haven't changed the Feed class at all.
>>
>> When I do something along the lines of:
>>
>> page = Page()
>> feed = Feed()
>> page.feeds.append(feed)
>>
>> the query that is issued is as follows:
>>
>> IntegrityError: (IntegrityError) pages_feeds.feed_id may not be NULL
>> u'INSERT INTO pages_feeds (page_id) VALUES (?)' (1,)
>>
>> So, clearly I have missed out the part of the config that explains
>> that adds in the second foreign key. Could anybody point me to where
>> please?
>
> you need a constructor and/or creator that generates Post() with the "feed"
> attached to it, like def __init__(self, feed): self.feed = feed, then the
> assoc proxy with creator=Post.
>
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