Proper autogenerate of __str__() implementation also for sqlalchemy classes?

I would like to display / print my sqlalchemy classes nice and clean.

In Is there a way to auto generate a __str__() implementation in python? the answer You can iterate instance attributes using vars, dir, ...:... helps in the case of simple classes.

When I try to apply it to a Sqlalchemy class (like the one from Introductory Tutorial of Python’s SQLAlchemy - see below), I get - apart from the member variables also the following entry as a member variable:

_sa_instance_state=<sqlalchemy.orm.state.InstanceState object at 0x000000004CEBCC0>

How can I avoid that this entry appears in the __str__ representation?

For the sake of completeness, I put the solution of the linked stackoverflow question below, too.

import osimport sysfrom sqlalchemy import Column, ForeignKey, Integer, Stringfrom sqlalchemy.ext.declarative import declarative_basefrom sqlalchemy.orm import relationshipfrom sqlalchemy import create_engineBase = declarative_base()class Person(Base):    __tablename__ = 'person'    # Here we define columns for the table person    # Notice that each column is also a normal Python instance attribute.    id = Column(Integer, primary_key=True)    name = Column(String(250), nullable=False)

As mentioned, this is the solution from Is there a way to auto generate a __str__() implementation in python?:

def auto_str(cls):    def __str__(self):        return '%s(%s)' % (            type(self).__name__,', '.join('%s=%s' % item for item in vars(self).items())        )    cls.__str__ = __str__    return cls@auto_strclass Foo(object):    def __init__(self, value_1, value_2):        self.attribute_1 = value_1         self.attribute_2 = value_2

Applied:

>>> str(Foo('bar', 'ping'))'Foo(attribute_2=ping, attribute_1=bar)'