修改SqlAlchemy模型时出现Unhashable Type错误

本文介绍了修改SqlAlchemy模型时出现Unhashable Type错误的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我正在使用实际上是从文档中复制来的最基本的烧瓶应用程序，并且收到了一个非常烦人的错误.我已经能够找到它，但不知道如何解决.我知道在实现flask-security时会出现问题，但该错误来自sqlalchemy内部.有什么建议吗?

I am using the most basic flask app practically copied from documentations, and am receiving an extremely annoying error. I've been able to trace it down but don't know how to solve it. I know the problem arises when implementing flask-security, but the error comes from inside sqlalchemy. Any advice?

from flask import Flask from flask.ext.sqlalchemy import SQLAlchemy import logging app = Flask(__name__) app.config['DEBUG'] = True app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///:memory:' # db = SQLAlchemy(app) 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): id = db.Column(db.Integer(), primary_key=True) name = db.Column(db.String(80), unique=True) description = db.Column(db.String(255)) def __init__(self, name, desc): self.name = name self.description = desc def __repr__(self): return '<Role: {}>'.format(str(self.name)) class User(db.Model): id = db.Column(db.Integer, primary_key=True) username = db.Column(db.String(255), unique=True) password = db.Column(db.String(255)) roles = db.relationship('Role', secondary=roles_users, backref=db.backref('users', lazy='dynamic')) def __init__(self, username, password): self.username = username self.password = password def __repr__(self): return '<User: {}>'.format(str(self.username)) def main(): db.create_all() adminRole = Role('Admin', 'Unrestricted') adminUser = User('admin', 'adminpassword') adminUser.roles = [adminRole] db.session.add(adminUser) db.sessionmit() app.run(debug=True) if __name__ == '__main__': LOG_FILENAME = 'test.log' logging.basicConfig(filename=LOG_FILENAME,level=logging.DEBUG,) logging.debug('This message should go to the log file') try: main() except: logging.exception('Got exception on main handler') raise

上面的代码可以正常工作.使用Flask-Security并将RoleMixin子类化(将 eq 和 ne 函数添加到模型中)时出现问题.

The above code works completely fine. The problem comes when using Flask-Security and subclassing RoleMixin (which adds the eq and ne functions to the model. Once the class becomes this:

class Role(db.Model): id = db.Column(db.Integer(), primary_key=True) name = db.Column(db.String(80), unique=True) description = db.Column(db.String(255)) def __init__(self, name, desc): self.name = name self.description = desc def __repr__(self): return '<Role: {}>'.format(str(self.name)) def __eq__(self, other): return (self.name == other or self.name == getattr(other, 'name', None)) def __ne__(self, other): return not self.__eq__(other)

我收到以下错误:

ERROR:root:Got exception on main handler Traceback (most recent call last): File "test.py", line 66, in <module> main() File "test.py", line 53, in main adminUser.roles = [adminRole] File "C:\Users\ramabodhi\Envs\test\lib\site-packages\sqlalchemy\orm\attributes.py", line 220, in __set__ instance_dict(instance), value, None) File "C:\Users\ramabodhi\Envs\test\lib\site-packages\sqlalchemy\orm\attributes.py", line 975, in set lambda adapter, i: adapter.adapt_like_to_iterable(i)) File "C:\Users\ramabodhi\Envs\test\lib\site-packages\sqlalchemy\orm\attributes.py", line 1010, in _set_iterable collections.bulk_replace(new_values, old_collection, new_collection) File "C:\Users\ramabodhi\Envs\test\lib\site-packages\sqlalchemy\orm\collections.py", line 782, in bulk_replace constants = existing_idset.intersection(values or ()) File "C:\Users\ramabodhi\Envs\test\lib\site-packages\sqlalchemy\util\_collections.py", line 592, in intersection result._members.update(self._working_set(members).intersection(other)) TypeError: unhashable type: 'Role' DEBUG:root:This message should go to the log file ERROR:root:Got exception on main handler Traceback (most recent call last): File "test.py", line 66, in <module> main() File "test.py", line 53, in main adminUser.roles = [adminRole] File "C:\Users\ramabodhi\Envs\test\lib\site-packages\sqlalchemy\orm\attributes.py", line 220, in __set__ instance_dict(instance), value, None) File "C:\Users\ramabodhi\Envs\test\lib\site-packages\sqlalchemy\orm\attributes.py", line 975, in set lambda adapter, i: adapter.adapt_like_to_iterable(i)) File "C:\Users\ramabodhi\Envs\test\lib\site-packages\sqlalchemy\orm\attributes.py", line 1010, in _set_iterable collections.bulk_replace(new_values, old_collection, new_collection) File "C:\Users\ramabodhi\Envs\test\lib\site-packages\sqlalchemy\orm\collections.py", line 782, in bulk_replace constants = existing_idset.intersection(values or ()) File "C:\Users\ramabodhi\Envs\test\lib\site-packages\sqlalchemy\util\_collections.py", line 592, in intersection result._members.update(self._working_set(members).intersection(other)) TypeError: unhashable type: 'Role'

我在python 3.3 Windows 7上，我所有的软件包都是最新的.

I am on python 3.3 windows 7 and all my packages are up to date.

推荐答案

对此我有一个解决方案"，但我想确保它是可行的解决方案，而不是不稳定的hack.

I have a "solution" for this, but I want to make sure its a viable solution and not an unstable hack.

我意识到向类中添加 ne 和 eq 函数需要添加 hash 函数，以使模型能够可散列的.所以现在可以正常工作了:

I realize that adding the ne and eq functions to the class requires the hash function to be added in order for the model to be hashable. So this is now working:

class Role(db.Model): id = db.Column(db.Integer(), primary_key=True) name = db.Column(db.String(80), unique=True) description = db.Column(db.String(255)) def __init__(self, name, desc): self.name = name self.description = desc def __repr__(self): return '<Role: {}>'.format(str(self.name)) def __eq__(self, other): return (self.name == other or self.name == getattr(other, 'name', None)) def __ne__(self, other): return not self.__eq__(other) def __hash__(self): return hash(self.name)

让我知道我是否做得正确，谢谢！

Let me know if I've done this properly, thanks!