python - Flask_login 中的 current_user 返回 NoneType

Question

在我的 forms.py 应用程序中，我有以下几行:

from flask_wtf import FlaskForm
from wtforms import SelectField, StringField, SubmitField, TextAreaField, PasswordField, BooleanField
from wtforms.validators import DataRequired
from flask_login import current_user

class LogForm(FlaskForm):
    #game, title, log, submit
    game = SelectField(u'Select Game', default='', coerce=str, choices=[(game.game_name, game.game_name) for game in current_user.games])
    game.choices = [(game.game_name, game.game_name) for game in current_user.games]
    title = StringField('Title', validators=[DataRequired()])
    log = TextAreaField('Game log', validators=[DataRequired()])
    submit = SubmitField('Update')

class RegisterForm(FlaskForm):
    username = StringField('Username', validators=[DataRequired()])
    email = StringField('Email', validators=[DataRequired()])
    password = PasswordField('Password', validators=[DataRequired()])

class LoginForm(FlaskForm):
    username = StringField('Username', validators=[DataRequired()])
    password = PasswordField('Password', validators=[DataRequired()])
    remember_me = BooleanField("Remember me")
    submit = SubmitField("Sign in")

当我运行代码时，出现以下错误:

>>> from app import db
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/AdityaD/iCloud Drive (Archive)/Desktop/flask_devlog/app/__init__.py", line 15, in <module>
    from app import routes, models
  File "/Users/AdityaD/iCloud Drive (Archive)/Desktop/flask_devlog/app/routes.py", line 7, in <module>
    from app.forms import LoginForm, LogForm
  File "/Users/AdityaD/iCloud Drive (Archive)/Desktop/flask_devlog/app/forms.py", line 7, in <module>
    print(current_user.id)
  File "/Users/AdityaD/iCloud Drive (Archive)/Desktop/flask_devlog/env/lib/python3.6/site-packages/werkzeug/local.py", line 347, in __getattr__
    return getattr(self._get_current_object(), name)
AttributeError: 'NoneType' object has no attribute 'id'

以下是 models.py 文件的相关部分，供引用

from app import db
from datetime import datetime
from werkzeug.security import generate_password_hash, check_password_hash
from flask_login import UserMixin
from app import login 

@login.user_loader
def load_user(id):
    return User.query.get(int(id))

class User(UserMixin, db.Model):
    __tablename__ = "User"
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(64))
    hashed_password = db.Column(db.String(128))
    games = db.relationship('Game', backref='creator', lazy=True)

    def set_password(self, password):
        self.hashed_password = generate_password_hash(password)

    def check_password(self, password):
        return check_password_hash(self.hashed_password, password)

    def __repr__(self):
        return f'<User {self.username}>'

我尝试将包含类似 if current_user is None 的 if 语句放入 LogForm 表单中，但它仍然不起作用。为什么会出现这种情况？救命!

编辑:在表单语句返回之前添加 is_authenticated 检查 AttributeError: 'NoneType' 对象没有属性 'is_authenticated'

Answer 1

要使flask_login正常工作，您需要确保您的代码具有以下方法，以便flask_login实际上可以根据给定的id登录用户

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

此外，为了让您的表单正确生成 game.choices 字段，您需要通过登录用户来确保您拥有 current_user 对象。

为了帮助您调试，请尝试 print(current_user) 如果您得到 AnonymousUser 对象，则表示您的用户未正确登录。