Now we're getting somewhere:
expressions = []
for tag in tag_list:
expressions += [Tag.tag==tag]
documents =
session.query(Document).join(Document.tags).filter(and_(*expressions))
Thanks to a Storm example I found. :)
On Mar 19, 8:12 am, Stodge <sto...@gmail.com> wrote:
> Ok so far I have this:
>
> expressions = []
> for tag in tag_list:
> expressions += session.query(Document).filter(Tag.tag==tag)
> documents =
> session.query(Document).join(Document.tags).filter(and_(*expressions))
>
> Doesn't work but it's progress! :)
>
> On Mar 18, 2:37 pm, Stodge <sto...@gmail.com> wrote:
>
> > Thanks that worked beautifully.
>
> > On a similar note, how would I match documents with only the tags that
> > I specify in the list? My naive attempt is:
>
> > for tag in tag_list:
> > session.query(Document).join(Document.tags).filter_by(tag=tag)
>
> > But that doesn't work.
>
> > On Mar 15, 10:54 am, "Michael Bayer" <mike...@zzzcomputing.com> wrote:
>
> > > Stodgewrote:
> > > > I have two classes with a third table:
>
> > > > document_tags = Table('document_tags', metadata,
> > > > Column('document_id', Integer, ForeignKey('documents.id')),
> > > > Column('tag_id', Integer, ForeignKey('tags.id'))
> > > > )
>
> > > > class Document(Base):
> > > > __tablename__ = 'documents'
>
> > > > id = Column(Integer, primary_key=True)
> > > > title = Column(String)
> > > > filename = Column(String)
> > > > tags = relation('Tag', secondary=document_tags, backref='tags')
>
> > > > def __init__(self, title, filename):
> > > > self.title = title
> > > > self.filename = filename
>
> > > > class Tag(Base):
> > > > __tablename__ = 'tags'
>
> > > > id = Column(Integer, primary_key=True)
> > > > tag = Column(String)
>
> > > > def __init__(self, tag):
> > > > self.tag = tag
>
> > > > I want to find all documents with tags in a given list of tags:
>
> > > > documents =
> > > > session.query(Document).filter(Document.tags.in_(tag_list))
>
> > > > except I get the familiar message that the "in_()" operator is not
> > > > currently implemented for many-to-one-relations.
>
> > > > I've searched and found some alternatives but I can't get any to work.
> > > > Is there an easy example that will make this work? Thanks
>
> > > if the error message says "many-to-one" then that's a bug. Your relation
> > > is many-to-many.
>
> > > in this case the syntactically easiest method is to use any().
> > > Document.tags.any(Tag.id.in_([t.id for t in tag_list])).
>
> > > A join could be more performant, which would be:
>
> > > query.join(Document.tags).filter(Tag.id.in_([t.id for t in tag_list]))
>
> > > > --
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>
>
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