[sqlalchemy] how to make many-to-many links against the same class with an association table

[Julien Iguchi-Cartigny]

Hi,

I've two classes CourseSet and CanonicalCourse (with the same parent)
which need to be connected in a many-to-many relationship.  But these
classes are mapped on the same table,  thus definition of the
association table seems redondant:

assoc_course_set_canonical_table = Table(
    'CM_COURSE_SET_CANON_ASSOC_T', Base.metadata,
    Column('CANON_COURSE', Integer,
        ForeignKey('CM_MEMBER_CONTAINER_T.MEMBER_CONTAINER_ID')),
    Column('COURSE_SET', Integer,
        ForeignKey('CM_MEMBER_CONTAINER_T.MEMBER_CONTAINER_ID'))
)

But i can't define the relationship between. I've the error:

Could not determine join condition between parent/child tables on
relationship CourseSet.canonicalCourses.  Specify a 'primaryjoin'
expression.  If 'secondary' is present, 'secondaryjoin' is needed as
well.

I must have miss something: i've tried several possibilities with
primaryjoin and secondaryjoin but nothing work. Is it because i'm
refering at the same foreign key in the associative table ?

Thank you.

Julien.

PS: The code for my two classes ('#' comments the two lines with the problem)

class CourseSet(AbstractContainer):
    parent_id = Column('PARENT_COURSE_SET', Integer,
        ForeignKey('CM_MEMBER_CONTAINER_T.ENTERPRISE_ID'))
    children = relationship("CourseSet", backref=backref('parent',
        remote_side=AbstractContainer.eid))
#    canonicalCourses = relationship("CanonicalCourse",
#        secondary="assoc_course_set_canonical_table")

    @classproperty
    def __mapper_args__(self):
        args = dict()
        args.update(AbstractContainer.__mapper_args__)
        args.update({'polymorphic_identity':
            'org.sakaiproject.coursemanagement.impl.CourseSetCmImpl'})
        return args

class CanonicalCourse(AbstractContainer):

    @classproperty
    def __mapper_args__(self):
        args = dict()
        args.update(AbstractContainer.__mapper_args__)
        args.update({'polymorphic_identity':
            'org.sakaiproject.coursemanagement.impl.CanonicalCourseCmImpl'})
        return args

PS: the parents of these classes:

class AbstractPersistent(object):
    version = Column('VERSION', Integer)
    last_modified_by = Column('LAST_MODIFIED_BY', String(255))
    last_modified_date = Column('LAST_MODIFIED_DATE', Date)
    created_by = Column('CREATED_BY', String(255))
    created_date = Column('CREATED_DATE', Date)

class AbstractNamed(AbstractPersistent):
    eid = Column('ENTERPRISE_ID', String(255))
    title = Column('TITLE', String(255))
    description = Column('DESCRIPTION', String(255))

class AbstractContainer(Base,AbstractNamed):
    __tablename__ = 'CM_MEMBER_CONTAINER_T'
    id = Column('MEMBER_CONTAINER_ID',Integer,primary_key=True)
    discriminator = Column('CLASS_DISCR', String(100))
    __mapper_args__ = {'polymorphic_on': discriminator }



-- 
"Trouble-a-cat limited"

-- 
You received this message because you are subscribed to the Google Groups 
"sqlalchemy" group.
To post to this group, send email to sqlalch...@googlegroups.com.
To unsubscribe from this group, send email to 
sqlalchemy+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/sqlalchemy?hl=en.