SQLAlchemy的：类型错误：unhashable类型创建实例，SQLAlchemy的

Question

试图更新代码，我得到一个错误：在Python 2.7 https://github.com/thrisp/flask-security至3.3

给出以下最基础的情况下

test.py：

from flask import Flask 
from flask.ext.sqlalchemy import SQLAlchemy 
from flask.ext.security import Security, UserMixin, RoleMixin, \ 
    SQLAlchemyUserDatastore 

app = Flask(__name__) 
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite://' 

db = SQLAlchemy(app) 
db.drop_all() 

roles_users = db.Table('roles_users', 
     db.Column('user_id', db.Integer(), db.ForeignKey('user.id')), 
     db.Column('role_id', db.Integer(), db.ForeignKey('role.id'))) 

class Role(db.Model, RoleMixin): 
     id = db.Column(db.Integer(), primary_key=True) 
     name = db.Column(db.String(80), unique=True) 
     description = db.Column(db.String(255)) 

class User(db.Model, UserMixin): 
    id = db.Column(db.Integer, primary_key=True) 
    email = db.Column(db.String(255), unique=True) 
    password = db.Column(db.String(255)) 
    last_login_at = db.Column(db.DateTime()) 
    current_login_at = db.Column(db.DateTime()) 
    last_login_ip = db.Column(db.String(100)) 
    current_login_ip = db.Column(db.String(100)) 
    login_count = db.Column(db.Integer) 
    active = db.Column(db.Boolean()) 
    confirmed_at = db.Column(db.DateTime()) 
    roles = db.relationship('Role', secondary=roles_users, 
          backref=db.backref('users', lazy='dynamic')) 


db.create_all() 
app.security = Security(app, datastore=SQLAlchemyUserDatastore(db, User, Role)) 
ds = app.extensions['security'].datastore 

def create_roles(): 
    for role in ('admin', 'editor', 'author'): 
     ds.create_role(name=role) 
    ds.commit() 

create_roles() 

def create_users(count=None): 
    users = [('matt@lp.com', 'password', ['admin'], True), 
      ('joe@lp.com', 'password', ['editor'], True), 
      ('dave@lp.com', 'password', ['admin', 'editor'], True), 
      ('jill@lp.com', 'password', ['author'], True), 
      ('tiya@lp.com', 'password', [], False)] 
    count = count or len(users) 

    for u in users[:count]: 
     pw = u[1] 
     ds.create_user(email=u[0], password=pw, 
         roles=u[2], active=u[3]) 
    ds.commit() 

create_users(1) 

导致错误：

Traceback (most recent call last): 
File "test.py", line 62, in <module> 
create_users(1) 
File "test.py", line 59, in create_users 
roles=u[2], active=u[3]) 
File "/media/lxch/686e26f8-c6d4-4448-8fe4-c19802726dcb/projects/current/public/flask-security/flask_security/datastore.py", line 164, in create_user 
user = self.user_model(**self._prepare_create_user_args(**kwargs)) 
File "<string>", line 4, in __init__ 
File "/home/lxch/.virtualenvs/p3/lib/python3.3/site-packages/sqlalchemy/orm/state.py", line 200, in _initialize_instance 
return manager.original_init(*mixed[1:], **kwargs) 
File "/home/lxch/.virtualenvs/p3/lib/python3.3/site-packages/sqlalchemy/ext/declarative/base.py", line 425, in _declarative_constructor 
setattr(self, k, kwargs[k]) 
File "/home/lxch/.virtualenvs/p3/lib/python3.3/site-packages/sqlalchemy/orm/attributes.py", line 303, in __set__ 
instance_dict(instance), value, None) 
File "/home/lxch/.virtualenvs/p3/lib/python3.3/site-packages/sqlalchemy/orm/attributes.py", line 1001, in set 
lambda adapter, i: adapter.adapt_like_to_iterable(i)) 
File "/home/lxch/.virtualenvs/p3/lib/python3.3/site-packages/sqlalchemy/orm/attributes.py", line 1036, in _set_iterable 
collections.bulk_replace(new_values, old_collection, new_collection) 
File "/home/lxch/.virtualenvs/p3/lib/python3.3/site-packages/sqlalchemy/orm/collections.py", line 803, in bulk_replace 
constants = existing_idset.intersection(values or()) 
File "/home/lxch/.virtualenvs/p3/lib/python3.3/site-packages/sqlalchemy/util/_collections.py", line 558, in intersection 
result._members.update(self._working_set(members).intersection(other)) 
TypeError: unhashable type: 'Role' 

我正在试图理解为什么以及到底是什么：

类型错误：unhashable类型：“角色”

知道的任何见解。

Answer 1

类似的问题在这里讨论：Unhashable Type error when modifying SqlAlchemy Models

溶液（或至少解决方法）是在你的角色类来定义哈希功能，这样的事情：

def __hash__(self): 
    return hash(self.name)