python - Error de relación SQLAlchemy: el objeto no tiene atributo ''c''

orm python-2.6

Question

Usé sqlautocode para generar mi modelo y todas las relaciones. Estoy tratando de hacer una consulta simple como

obj = session.query(Venue).filter(Venue.symbol=="CARNEGIE_HALL").one()

Por algún motivo sigo recibiendo este mensaje de error:

File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/relationships.py", line 331, in _annotate_present_fks
          secondarycols = util.column_set(self.secondary.c)
      AttributeError: ''Event'' object has no attribute ''c''

Si comento las definiciones de relación, entonces la consulta anterior funciona. Las definiciones de relación generadas por sqlautocode me parecen correctas pero soy nuevo en SqlAlchemy. No estoy seguro de cómo solucionar esto. Intenté cambiar de relación () a relación () pero sigo teniendo el mismo error.

Usando sqlalchemy 0.8.2 y sqlautocode 0.6.

Tenga en cuenta que hay una relación de muchos a uno entre Event y Event_Type y una relación de varios a uno entre Event y Venue.

model.py

DeclarativeBase = declarative_base()
metadata = DeclarativeBase.metadata
metadata.bind = engine

Event = Table(u''Event'', metadata,
    Column(u''id'', INTEGER(), primary_key=True, nullable=False),
    Column(u''venue_id'', INTEGER(), ForeignKey(''Venue.id''), nullable=False),
    Column(u''event_type_id'', INTEGER(), ForeignKey(''Event_Type.id''), nullable=False),
)

Venue = Table(u''Venue'', metadata,
    Column(u''id'', INTEGER(), ForeignKey(''Obj.id''), primary_key=True, nullable=False),
    Column(u''venue_type_id'', INTEGER(), ForeignKey(''Venue_Type.id''), nullable=False),
    Column(u''name'', VARCHAR(length=100), nullable=False),
    Column(u''symbol'', VARCHAR(length=50), nullable=False),
)

class Event(DeclarativeBase):
    __table__ = Event


    #relation definitions
    Event_Type = relation(''EventType'', primaryjoin=''Event.event_type_id==EventType.id'')
    Venue = relation(''Venue'', primaryjoin=''Event.venue_id==Venue.id'')


class EventType(DeclarativeBase):
    __tablename__ = ''Event_Type''

    __table_args__ = {}

    #column definitions
    code = Column(u''code'', VARCHAR(length=50), nullable=False)
    description = Column(u''description'', VARCHAR(length=250))
    id = Column(u''id'', INTEGER(), primary_key=True, nullable=False)
    name = Column(u''name'', VARCHAR(length=100), nullable=False)

    #relation definitions
    Venues = relation(''Venue'', primaryjoin=''EventType.id==Event.event_type_id'', secondary=Event, secondaryjoin=''Event.venue_id==Venue.id'')


class Venue(DeclarativeBase):
    __table__ = Venue


    #relation definitions
    Event_Types = relation(''EventType'', primaryjoin=''Venue.id==Event.venue_id'', secondary=Event, secondaryjoin=''Event.event_type_id==EventType.id'')

Registro de errores

  mod_wsgi (pid=10861): Exception occurred processing WSGI script ''/home/uname/web/html/foo/app/main.py''.
  Traceback (most recent call last):
    File "/home/uname/web/html/foo/app/main.py", line 208, in application
      return callback(environ, start_response)
    File "/home/uname/web/html/foo/app/main.py", line 68, in monitor
      obj = session.query(Venue).filter(Venue.symbol=="CARNEGIE_HALL").one()
    File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/session.py", line 1106, in query
      return self._query_cls(entities, self, **kwargs)
    File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 115, in __init__
      self._set_entities(entities)
    File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 124, in _set_entities
      self._set_entity_selectables(self._entities)
    File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 157, in _set_entity_selectables
      ent.setup_entity(*d[entity])
    File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/query.py", line 2728, in setup_entity
      self._with_polymorphic = ext_info.with_polymorphic_mappers
    File "/usr/lib64/python2.6/site-packages/sqlalchemy/util/langhelpers.py", line 614, in __get__
      obj.__dict__[self.__name__] = result = self.fget(obj)
    File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/mapper.py", line 1426, in _with_polymorphic_mappers
      configure_mappers()
    File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/mapper.py", line 2121, in configure_mappers
      mapper._post_configure_properties()
    File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/mapper.py", line 1243, in _post_configure_properties
      prop.init()
    File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/interfaces.py", line 231, in init
      self.do_init()
    File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/properties.py", line 1028, in do_init
      self._setup_join_conditions()
    File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/properties.py", line 1102, in _setup_join_conditions
      can_be_synced_fn=self._columns_are_mapped
    File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/relationships.py", line 115, in __init__
      self._annotate_fks()
    File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/relationships.py", line 311, in _annotate_fks
      self._annotate_present_fks()
    File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/relationships.py", line 331, in _annotate_present_fks
      secondarycols = util.column_set(self.secondary.c)
  AttributeError: ''Event'' object has no attribute ''c''

Answer 1

no puedes decir esto

Venues = relation(''Venue'', primaryjoin=''EventType.id==Event.event_type_id'', secondary=Event, secondaryjoin=''Event.venue_id==Venue.id'')

necesitarías decir esto:

Venues = relation(''Venue'', primaryjoin=''EventType.id==Event.event_type_id'', secondary=Event.__table__, secondaryjoin=''Event.venue_id==Venue.id'')

"secundario" solo espera un objeto Table, no una clase mapeada.

También tenga en cuenta que SQLAlchemy recomienda el patrón de objeto de asociación , en lugar de realizar configuraciones "secundarias" sofisticadas, para mantener este tipo de cosas más claras.