我正在尝试学习Flask，但似乎UserMixin无法使用。

Question

更准确地说，我目前正在学习Flask，来自Corey Schafers的教程系列，并处于登录验证阶段，一切都看起来很好，但在尝试登录后，我得到了这个错误：

AttributeError
AttributeError: 'User' object has no attribute 'is_active'

Traceback (most recent call last)
File "C:\Users\panda\Desktop\HDD\Programs\Python3\Lib\site-packages\flask\app.py", line 2463, in __call__
return self.wsgi_app(environ, start_response)
File "C:\Users\panda\Desktop\HDD\Programs\Python3\Lib\site-packages\flask\app.py", line 2449, in wsgi_app
response = self.handle_exception(e)
File "C:\Users\panda\Desktop\HDD\Programs\Python3\Lib\site-packages\flask\app.py", line 1866, in handle_exception
reraise(exc_type, exc_value, tb)
File "C:\Users\panda\Desktop\HDD\Programs\Python3\Lib\site-packages\flask\_compat.py", line 39, in reraise
raise value
File "C:\Users\panda\Desktop\HDD\Programs\Python3\Lib\site-packages\flask\app.py", line 2446, in wsgi_app
response = self.full_dispatch_request()
File "C:\Users\panda\Desktop\HDD\Programs\Python3\Lib\site-packages\flask\app.py", line 1951, in full_dispatch_request
rv = self.handle_user_exception(e)
File "C:\Users\panda\Desktop\HDD\Programs\Python3\Lib\site-packages\flask\app.py", line 1820, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "C:\Users\panda\Desktop\HDD\Programs\Python3\Lib\site-packages\flask\_compat.py", line 39, in reraise
raise value
File "C:\Users\panda\Desktop\HDD\Programs\Python3\Lib\site-packages\flask\app.py", line 1949, in full_dispatch_request
rv = self.dispatch_request()
File "C:\Users\panda\Desktop\HDD\Programs\Python3\Lib\site-packages\flask\app.py", line 1935, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "C:\Users\panda\Desktop\HDD\Documents\Code\Python\Flask\flaskblog\routes.py", line 60, in login
login_user(user, remember=form.remember.data)
File "C:\Users\panda\Desktop\HDD\Programs\Python3\Lib\site-packages\flask_login\utils.py", line 158, in login_user
if not force and not user.is_active:

我的代码中定义了 User 类，代码如下：

from datetime import datetime
from flaskblog import db, login_manager
from flask_login import UserMixin



@login_manager.user_loader
def load_user(user_id):
    return User.query.get(int(user_id))


class User(UserMixin, db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(20), unique=True, nullable=False)
    email = db.Column(db.String(120), unique=True, nullable=False)
    image_file = db.Column(db.String(20), nullable=False, default='default.jpg')
    password = db.Column(db.String(60), nullable=False)
    posts = db.relationship('Post', backref='author', lazy=True)


    def __repr__(self):
        return f"User('{self.username}', '{self.email}', '{self.image_file}')"

我的init.py文件长这样：

。

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_bcrypt import Bcrypt
from flask_login import LoginManager

app = Flask(__name__)
app.secret_key = '5791628bb0b13ce0c676dfde280ba245'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///site.db'
db = SQLAlchemy(app)
login_manager = LoginManager(app)


bcrypt = Bcrypt(app)
from flaskblog import routes

我的路由到登录页面的代码如下：

from flaskblog.models import User, Post
from flask import render_template, url_for, flash, redirect
from flaskblog.forms import RegistrationForm, LoginForm
from flaskblog import app, db, bcrypt
from flask_login import login_user

@app.route("/login", methods=['GET', 'POST'])
def login():

    form = LoginForm()
    if form.validate_on_submit():
        user = User.query.filter_by(email=form.email.data).first()
        if user and bcrypt.check_password_hash(user.password, form.password.data):
            login_user(user, remember=form.remember.data)
            return redirect(url_for('home'))
        else:
            flash('Login Unsuccessful. Please check email and password', 'danger')
    return render_template('login.html', title='Login', form=form)

最奇怪的是，即使在我编辑类“User”并使其包含方法“is_active”，错误仍然继续出现。

from datetime import datetime
from flaskblog import db, login_manager
from flask_login import UserMixin



@login_manager.user_loader
def load_user(user_id):
    return User.query.get(int(user_id))


class User(UserMixin, db.Model):


    def is_active():
        return True


    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(20), unique=True, nullable=False)
    email = db.Column(db.String(120), unique=True, nullable=False)
    image_file = db.Column(db.String(20), nullable=False, default='default.jpg')
    password = db.Column(db.String(60), nullable=False)
    posts = db.relationship('Post', backref='author', lazy=True)


    def __repr__(self):
        return f"User('{self.username}', '{self.email}', '{self.image_file}')"

同样的问题也发生在多个操作系统和多台计算机上，如果这对您有帮助的话。

- Vlastimil Urban

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请添加实际的错误描述，而不是链接到图像。 - Devesh Kumar Singh

我应该复制 Flask 调试器的整个输出还是只复制错误本身？ - Vlastimil Urban

无论你认为对回答者有帮助的内容，请同时查看https://stackoverflow.com/help/how-to-ask。 - Devesh Kumar Singh

我也一直在看Corey的教程，但是我在使用current_user时遇到了一些奇怪的问题，无法更新他的属性！ - BHA Bilel

Answer 1

我认为你的继承顺序是错误的。

尝试以这种方式创建你的类：

class User(db.Model, UserMixin):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(20), unique=True, nullable=False)
    email = db.Column(db.String(120), unique=True, nullable=False)
    image_file = db.Column(db.String(20), nullable=False, default='default.jpg')
    password = db.Column(db.String(60), nullable=False)
    posts = db.relationship('Post', backref='author', lazy=True)

请查看答案，以更详细地了解：Python中的super()如何处理多重继承？

如果可以，请告诉我。

---

编辑1：

没有看到LoginManager的初始化。根据flask_login包中的文档，应该像这样写：

login_manager = LoginManager(app)

- Sharath

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谢谢，但不幸的是这对我没有任何改变。 - Vlastimil Urban

你能同时将错误堆栈跟踪添加到问题中吗？ - Sharath

已使用LoginManager编辑了代码。看到你的代码中缺少这个。 - Sharath