[Sqlalchemy-tickets] Issue #4298: regression in strategy pathing (zzzeek/sqlalchemy)

[Michael B. <iss...@bi...>]

New issue 4298: regression in strategy pathing
https://bitbucket.org/zzzeek/sqlalchemy/issues/4298/regression-in-strategy-pathing

Michael Bayer:

due to #4287

```
#!python


from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.ext.declarative import declared_attr

Base = declarative_base()


class A(Base):
    __tablename__ = 'a'

    id = Column(Integer, primary_key=True)
    data = Column(String)
    bs = relationship("B")


class B(Base):
    __tablename__ = 'b'

    id = Column(Integer, primary_key=True)
    aid = Column(ForeignKey('a.id'))
    cs = relationship("C")


class C(Base):
    __tablename__ = 'c'

    id = Column(Integer, primary_key=True)
    bid = Column(ForeignKey('b.id'))

e = create_engine("sqlite://", echo=True)
Base.metadata.create_all(e)

s = Session(e)
s.add(A(bs=[B(cs=[C()])]))
s.commit()
s.close()

a1 = s.query(A).options(Load(A).lazyload("*")).first()
a1.bs[0].cs


```


```
#!python

Traceback (most recent call last):
  File "test.py", line 40, in <module>
    a1.bs[0].cs
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/orm/attributes.py", line 242, in __get__
    return self.impl.get(instance_state(instance), dict_)
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/orm/attributes.py", line 599, in get
    value = self.callable_(state, passive)
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/orm/strategies.py", line 631, in _load_for_state
    session, state, primary_key_identity, passive)
  File "<string>", line 1, in <lambda>
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/orm/strategies.py", line 713, in _emit_lazyload
    state.load_options, effective_path
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/ext/baked.py", line 185, in _add_lazyload_options
    cache_key = opt._generate_cache_key(cache_path)
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/orm/strategy_options.py", line 92, in _generate_cache_key
    chopped = self._chop_path(loader_path, path)
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/orm/strategy_options.py", line 389, in _chop_path
    elif c_token.is_mapper and p_token.is_mapper and \
AttributeError: 'str' object has no attribute 'is_mapper'

```