Hello I don't understand why the backref 'relation_b' of relationship 'relation_a' is not properly set when declaring 'relation_a'. Below is an example that highlight this situation. I must probably miss the philosophy being relation backref. What should I do to get backref working from the beginning?
from sqlalchemy import * from sqlalchemy.orm import * from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() _relation_a_table = Table('relation_a', Base.metadata, Column('id', Integer, primary_key=True) ) _relation_b_table = Table('relation_b', Base.metadata, Column('id', Integer, primary_key=True), ForeignKeyConstraint(['id'], ['relation_a.id']) ) class RelationA(Base): __table__ = _relation_a_table class RelationB(Base): __table__ = _relation_b_table relation_a = relationship('RelationA', backref='relation_b') if __name__ == '__main__': engine = create_engine('postgresql://xxxx@localhost:5432/xxxx') Session = sessionmaker(bind=engine) session = Session() print RelationA.__dict__.has_key('relation_b') q1 = session.query(RelationA).outerjoin(RelationA.relation_b) print RelationA.__dict__.has_key('relation_b') q2 = session.query(RelationA.id).outerjoin(RelationA.relation_b) # Output: # False # True # Output when q1 (line 31) is commented out: # False # False # Traceback (most recent call last): # File "/my_path/dummy.py", line 35, in <module> # q2 = session.query(RelationA.id).outerjoin(RelationA.relation_b) # AttributeError: type object 'RelationA' has no attribute 'relation_b' -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy?hl=en. For more options, visit https://groups.google.com/groups/opt_out.