Flask viele bis viele Spalte macht AttributeError: 'NoneType' Objekt hat kein Attribut '_sa_instance_state'

Question

Wenn Gruppe in view.py macht, möchte ich viele Benutzer für group.users [refer from_json (in model.py)]

jedoch einmal Benutzer spielt keine Rolle, aber viele Anwender ist, dass Problem

'AttributeError: 'NoneType' object has no attribute '_sa_instance_state'' 

model.py

user_group_relationship = db.Table('user_group_relationship', 
          db.Column('user_id', db.Integer, 
          db.ForeignKey('users.id'), nullable=False), 
          db.Column('group_id', db.Integer, 
          db.ForeignKey('groups.id'), nullable=False), 
          db.PrimaryKeyConstraint('user_id',`enter code here`'group_id')) 

class User(db.Model): 
    __tablename__ = 'users' 
    id = db.Column(db.Integer, primary_key=True) 
    username = db.Column(db.String(64), unique=True, index=True) 
    realname = db.Column(db.Text) 
    password_hash = db.Column(db.String(128)) 
    confirmed = db.Column(db.Boolean) 
    picture = db.Column(db.Text) 
    groups = db.relationship('Group', 
      secondary=user_group_relationship, 
      backref=db.backref('user', lazy='dynamic'), 
      lazy='dynamic') 
    news = db.relationship('News', backref='author', lazy='dynamic') 
    comments = db.relationship('Comment', backref='author', lazy='dynamic') 


class Group(db.Model): 
    __tablename__ = 'groups' 
    id = db.Column(db.Integer, primary_key=True) 
    name = db.Column(db.String(64), unique=True, index=True) 
    description = db.Column(db.Text) 
    created_at = db.Column(db.DateTime, index=True, default=datetime.utcnow) 

    users = db.relationship('User', 
      secondary=user_group_relationship, 
      passive_deletes=True, 
      backref=db.backref('group', lazy='dynamic'), 
       lazy='dynamic') 
    news = db.relationship('News', backref='house', lazy='dynamic') 

    def from_json(json_group) 
     name = json_group.get('name') 
     if name is None or name == '': 
      raise ValidationError('group does not have a name') 
     description = json_group.get('description') 
     group = Group(name, description) 
     users = json_group.get('users') 

     if type(users) == list and users is not None and len(users) >= 1: 
     group.users = [ User.query.filter_by(id=user_id).first() for user_id in users]\ 
      if User.query.filter_by(id=user_id).count() != 0 ] 
    return group 

Hier ist meine Ansicht Modell. Wenn Gruppe erstellen, hat Gruppe from_json von Modell beziehen

@api.route('/groups', methods=['POST']) 
@auth.login_required 
@cross_origin(expose_headers='Location') 
def post_group(): 
    group = Group.from_json(request.json) 
    if Group.query.filter_by(name=group.name).count() != 0: 
     return forbidden('Already name is exist') 
    db.session.add(group) 
    db.session.commit() 
    resp = make_response() 
    resp.headers['Location'] = url_for('api.get_group', group_id=group.id) 
    return resp 

Hier Debug Log

<!-- 

Traceback (most recent call last): 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/flask/app.py", line 1820, in wsgi_app 
    response = self.make_response(self.handle_exception(e)) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/flask_cors/extension.py", line 188, in wrapped_function 
    return cors_after_request(app.make_response(f(*args, **kwargs))) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/flask/app.py", line 1403, in handle_exception 
    reraise(exc_type, exc_value, tb) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/flask/app.py", line 1817, in wsgi_app 
    response = self.full_dispatch_request() 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request 
    rv = self.handle_user_exception(e) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/flask_cors/extension.py", line 188, in wrapped_function 
    return cors_after_request(app.make_response(f(*args, **kwargs))) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/flask/app.py", line 1381, in handle_user_exception 
    reraise(exc_type, exc_value, tb) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request 
    rv = self.dispatch_request() 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/flask/app.py", line 1461, in dispatch_request 
    return self.view_functions[rule.endpoint](**req.view_args) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/flask_httpauth.py", line 62, in decorated 
    return f(*args, **kwargs) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/flask_cors/decorator.py", line 127, in wrapped_function 
    resp = make_response(f(*args, **kwargs)) 
    File "/home/ju1115kr/afoccert/app/api_1_0/groups.py", line 60, in post_group 
    group = Group.from_json(request.json) 
    File "/home/ju1115kr/afoccert/app/models.py", line 181, in from_json 
    group.users = [ User.query.filter_by(id=user_id).first() for user_id in users] 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/sqlalchemy/orm/attributes.py", line 224, in __set__ 
    instance_dict(instance), value, None) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/sqlalchemy/orm/dynamic.py", line 139, in set 
    self._set_iterable(state, dict_, value) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/sqlalchemy/orm/dynamic.py", line 161, in _set_iterable 
    collection_history=collection_history) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/sqlalchemy/orm/dynamic.py", line 99, in fire_append_event 
    value = fn(state, value, initiator or self._append_token) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/sqlalchemy/orm/attributes.py", line 1190, in emit_backref_from_collection_append_event 
    passive=PASSIVE_NO_FETCH) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/sqlalchemy/orm/dynamic.py", line 202, in append 
    self.fire_append_event(state, dict_, value, initiator) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/sqlalchemy/orm/dynamic.py", line 99, in fire_append_event 
    value = fn(state, value, initiator or self._append_token) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/sqlalchemy/orm/unitofwork.py", line 46, in append 
    sess._save_or_update_state(item_state) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 1606, in _save_or_update_state 
    halt_on=self._contains_state): 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/sqlalchemy/orm/mapper.py", line 2610, in cascade_iterator 
    visited_states, halt_on)) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/sqlalchemy/orm/relationships.py", line 1528, in cascade_iterator 
    get_all_pending(state, dict_) 
    File "/home/ju1115kr/venv/lib/python2.7/site-packages/sqlalchemy/orm/dynamic.py", line 185, in get_all_pending 
    c.all_items 
AttributeError: 'NoneType' object has no attribute '_sa_instance_state' 

Answer 1

von mir gelöst.

Wenn

users = json_group.get('users') 

    if type(users) == list and users is not None and len(users) >= 1: 
    group.users = [ User.query.filter_by(id=user_id).first() for user_id in users]\ 
     if User.query.filter_by(id=user_id).count() != 0 ] 

users ‚s Typ Unicode ist. so,

>>> users=['ju1115kr'] 


>>> type(users) 
>>> unicode 
>>> for i in users: 
>>>  print i 
    [ 
    ' 
    j 
    u 
    1 
    1 
    1 
    5 
    k 
    r 
    ' 
    ] 

so fixiert ich es

user_list = [ str(user) for user in users.strip('[]').split(',') ] 
if type(user_list) == list and user_list is not None and len(user_list) >= 1: 
    group.users = [ User.query.filter_by(id=user_id).first() for user_id in user_list]\ 
     if User.query.filter_by(id=user_id).count() != 0 ]