title: SQLalchemy AttributeError: 'str' object has no attribute '_sa_instance_state'
body: <p>I'm trying to add an item to my database with SQLAlchemy + Python, but keep getting an error.</p>
  
  <p>My database_setup.py:</p>
  
  <pre><code>class company(Base):
      __tablename__ = 'company'
      compID = Column(Integer, primary_key = True)
      name = Column(String(80), nullable = False)
  
  class item(Base):
      __tablename__ = 'items'
      itemID = Column(Integer, primary_key = True)
      name = Column(String(80), nullable = False)
      category = Column(String(250))
      description = Column(String(250))
      price = Column(String(8))
      compID = Column(Integer, ForeignKey('company.compID'))
      company = relationship(company)
  </code></pre>
  
  <p>after importing sqlalchemy to my terminal, I define an item to insert:</p>
  
  <pre><code>JawboneUP3 = item(
      itemID="1",
      name="Jawbone UP3",
      description="The latest UP!", 
      category="tracker",
      price="$174.99",
      company="Jawbone"
  )
  </code></pre>
  
  <p>and draw a session to add and commit:</p>
  
  <pre><code>session.add(JawboneUP3)
  session.commit()
  </code></pre>
  
  <p>When I submit, I keep getting this error:</p>
  
  <pre><code>Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 1399, in add
      self._save_or_update_state(state)
    File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 1417, in _save_or_update_state
      halt_on=self._contains_state):
    File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/mapper.py", line 2037, in cascade_iterator
      parent_dict, visited_states, halt_on))
    File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/properties.py", line 932, in cascade_iterator
      get_all_pending(state, dict_)
    File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/attributes.py", line 761, in get_all_pending
     ret = [(instance_state(current), current)]
  AttributeError: 'str' object has no attribute '_sa_instance_state'
  </code></pre>
  
  <p>I have added a 'Jawbone' object to my company table, that I understand my 'JawboneUP3' should relate back to. This object was added correctly through a browser form that I enabled via my webserver script. I believe I should be able to add items right from the terminal though.</p>