当在view.py中创建组时，我想为group.users的许多用户创建[引用from_json（在model.py中）]
然而，一旦用户不重要，但很多用户就是那个问题
'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
这是我的视图模型。创建组时，Group已从模型
引用from_json@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
此处的调试日志
<!--
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'
答案 0 :(得分：0)
由我自己解决。
何时
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的类型是unicode。
所以，
>>> users=['ju1115kr']
>>> type(users)
>>> unicode
>>> for i in users:
>>> print i
[
'
j
u
1
1
1
5
k
r
'
]
所以我修好了
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 ]