Stodge wrote:
> 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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