Can only define secondary relationship using association table object but not name

Question

Trying to create an association relationship between the classes Note and Document. The problem I'm facing is that my secondary relationship only works when I use the association table object and not that table name. What I mean is that the relationship:

notes = relationship(u'Note', secondary=t_Documented, backref='documents')

works but the following does NOT work:

notes = relationship(u'Note', secondary='Documented', backref='documents')

When querying, I get the error:

sqlalchemy.exc.InvalidRequestError: When initializing mapper Mapper|Document|Document, expression 'Documented' failed to locate a name ("name 'Documented' is not defined"). If this is a class name, consider adding this relationship() to the class after both dependent classes have been defined.

I would rather use the name as my model is generated using sqlacodegen.

Moreover, SQLAlchemy docs say I can use the name (http://docs.sqlalchemy.org/en/rel_0_9/orm/relationships.html#many-to-many) with caveta "with the declarative extension in use". I Googled the term which led me to this. Question is how in my case can I augment the Base.

# model.py
# coding: utf-8
from sqlalchemy import Column, Date, DateTime, ForeignKey, ForeignKeyConstraint, Index, Integer, Numeric, String, Table, Text, text
from sqlalchemy.orm import backref, relationship
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()
metadata = Base.metadata

t_Documented = Table(
    'Documented', metadata,
    Column('id', Integer, primary_key=True),
    Column('note_id', ForeignKey(u'MySchema.Note.id'), nullable=False),
    Column('document_id', ForeignKey(u'MySchema.Document.id'), nullable=False, index=True),
    Column('inserted', DateTime, nullable=False, server_default=text("'0000-00-00 00:00:00'")),
    Column('updated', DateTime, nullable=False, server_default=text("'0000-00-00 00:00:00'")),
    Index('Documented_AK1', 'note_id', 'document_id'),
    schema='MySchema'
)

class Note(Base):
    __tablename__ = 'Note'
    __table_args__ = {u'schema': 'MySchema'}

    id = Column(Integer, primary_key=True)

class Document(Note):
    __tablename__ = 'Document'
    __table_args__ = {u'schema': 'MySchema'}

    id = Column(ForeignKey(u'MySchema.Note.id'), primary_key=True)
    title = Column(String(100), nullable=False)
    author = Column(String(100), nullable=False)

    notes = relationship(u'Note', secondary='Documented', backref='documents')

Using SQLAlchemy 0.9.4 and Python 2.6.6. Connector is MySQLDB and I'm using MySQL database.

Answer 1

your table has a schema of "MySchema" so that has to be part of it:

notes = relationship(u'Note', secondary='MySchema.Documented', backref='documents')