[sqlalchemy] AttributeError: Neither 'QueryableAttribute' object nor 'Comparator' object has an attribute '__visit_name__'

[Dane K Barney]

I am using SQLAlchemy 1.4.2 and have been encountering this strange error 
message which I've managed to boil down to this minimal example:

import sqlalchemy as sa
from sqlalchemy.orm import declarative_base, relationship

Base = declarative_base()

class Parent(Base):
    __tablename__ = "parent"
    id = sa.Column(sa.Integer, primary_key=True)


class Child(Base):
    __tablename__ = "child"
    id = sa.Column(sa.Integer, primary_key=True)
    parent_id = sa.Column(sa.Integer, sa.ForeignKey("parent.id"))
    parent = relationship("Parent")


statement = sa.select([Child.id]).join(Child.parent).where(Parent.id == 
sa.bindparam("id"))

statement = statement.params(id=10)


The call to statement.params(...) is throwing the following stacktrace. Can 
anyone tell me what I'm doing wrong?

Traceback (most recent call last):
  File "test_sqlalchemy_error.py", line 20, in <module>
    statement = statement.params(id=10)
  File ".venv/lib/python3.7/site-packages/sqlalchemy/sql/elements.py", line 
346, in params
    return self._replace_params(False, optionaldict, kwargs)
  File ".venv/lib/python3.7/site-packages/sqlalchemy/sql/elements.py", line 
363, in _replace_params
    return cloned_traverse(self, {}, {"bindparam": visit_bindparam})
  File ".venv/lib/python3.7/site-packages/sqlalchemy/sql/visitors.py", line 
742, in cloned_traverse
    obj = clone(obj, deferred_copy_internals=deferred_copy_internals)
  File ".venv/lib/python3.7/site-packages/sqlalchemy/sql/visitors.py", line 
735, in clone
    newelem._copy_internals(clone=clone, **kw)
  File ".venv/lib/python3.7/site-packages/sqlalchemy/sql/selectable.py", 
line 5208, in _copy_internals
    clone=clone, omit_attrs=("_from_obj",), **kw
  File ".venv/lib/python3.7/site-packages/sqlalchemy/sql/traversals.py", 
line 718, in _copy_internals
    result = meth(attrname, self, obj, **kw)
  File ".venv/lib/python3.7/site-packages/sqlalchemy/sql/traversals.py", 
line 777, in visit_setup_join_tuple
    for (target, onclause, from_, flags) in element
  File ".venv/lib/python3.7/site-packages/sqlalchemy/sql/traversals.py", 
line 777, in <genexpr>
    for (target, onclause, from_, flags) in element
  File ".venv/lib/python3.7/site-packages/sqlalchemy/sql/visitors.py", line 
736, in clone
    meth = visitors.get(newelem.__visit_name__, None)
  File ".venv/lib/python3.7/site-packages/sqlalchemy/orm/attributes.py", 
line 308, in __getattr__
    replace_context=err,
  File ".venv/lib/python3.7/site-packages/sqlalchemy/util/compat.py", line 
198, in raise_
    raise exception
AttributeError: Neither 'QueryableAttribute' object nor 'Comparator' object 
associated with Child.parent has an attribute '__visit_name__'


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http://www.sqlalchemy.org/

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