Flask-Login @login-required 装饰器在会话过期后不会重定向到登录页面

Question

UPDATE更新

It appears that the Flask redirect (response code 302) below is being passed as the response to the _dash-update-component request:下面的 Flask 重定向（响应代码 302）似乎作为对_dash-update-component请求的响应传递：

b'<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">\n<title>Redirecting...</title>\n<h1>Redirecting...</h1>\n<p>You should be redirected automatically to target URL: <a href="/login">/login</a>.  If not click the link.'

This explains the SyntaxError thrown by dash_renderer below, so this led me to add the following in server.py :这解释了下面 dash_renderer 抛出的 SyntaxError，所以这导致我在server.py添加以下内容：

@server.after_request
def check_response(response):

    redirecting = 'Redirecting...' in response.get_data().decode('utf-8')
    dash_response = request.path=='/_dash-update-component'

    return make_response('', 204) if redirecting and dash_response else response

Now I can emulate a Dash-like PreventUpdate by returning a "204 No-Content" response to the dash component, but then I am not receiving the additional request for the redirect back to the login page.现在我可以通过向 dash 组件返回“204 No-Content”响应来模拟类似 Dash 的PreventUpdate ，但是我没有收到重定向回登录页面的额外请求。 Commenting out the after_request function and then tracking the requests seen by before_request , it's actually shown that the login() route is invoked and render_template('login.html') is returned, but it's simply not rendered in the browser....注释掉after_request函数，然后跟踪before_request看到的请求，实际上表明调用了login()路由并返回了render_template('login.html') ，但它根本没有在浏览器中呈现......

ORIGINAL POST BELOW下面的原始帖子

I've spent the better part of the last few days attempting to overhaul our login procedures to add some quality of life update and modifications.过去几天，我大部分时间都在尝试修改我们的登录程序，以增加一些生活质量的更新和修改。 For the purposes of this question, I'm interested in logging out our users after a certain period of inactivity in the main Dash application.出于这个问题的目的，我有兴趣在主 Dash 应用程序中一段时间不活动后注销我们的用户。

My approach was to register routes for our Login page, and then point a Flask route for /dashapp to the response returned by app.index() where app points to the Dash application.我的方法是为我们的登录页面注册路由，然后将/dashapp的 Flask 路由指向app.index()返回的响应，其中app指向 Dash 应用程序。 Once they are logged into the Dash application, I have a before_request decorator that will update the session modified attribute and the session expiration (5 seconds for the purposes of testing).一旦他们登录到 Dash 应用程序，我就有了一个before_request装饰器，它将更新会话修改属性和会话过期时间（用于测试目的是 5 秒）。 I've also applied the @login_required decorator to this invoked function, so that login_manager.unauthorized_handler is invoked if the user is no longer authenticated when triggering the before_request decorator.我还申请了@login_required装饰这个调用的功能，使login_manager.unauthorized_handler如果触发，当用户不再验证调用before_request装饰。 I think my logic is sound here, but I am still having issues which I will describe below.我认为我的逻辑在这里是合理的，但我仍然遇到问题，我将在下面描述。

I am able to login my users and redirect them to the main Dash application at /dashapp , and I can use the application without issues.我能够登录我的用户并将他们重定向到位于/dashapp的主 Dash 应用程序，并且我可以/dashapp使用该应用程序。 Now when I wait the 5 seconds to allow for the session to expire, clicking on a component in my Dash application that triggers a dash callback produces the following error in the console:现在，当我等待 5 秒钟以允许会话过期时，单击 Dash 应用程序中触发 dash 回调的组件会在控制台中产生以下错误：

dash_renderer.v1_7_0m1602118443.min.js:20 SyntaxError: Unexpected token < in JSON at position 0 dash_renderer.v1_7_0m1602118443.min.js:20 SyntaxError: Unexpected token < in JSON at position 0

I'm aware that some function is expecting a JSON response, and has apparently received an HTML response instead, but I can't pin down what that is.我知道某些函数需要 JSON 响应，并且显然收到了 HTML 响应，但我无法确定那是什么。 It's also preventing my redirection back to the login page that I expected to be invoked when the user was no longer authenticated and triggered the before_request decorator.它还阻止我重定向回登录页面，当用户不再通过身份验证并触发before_request装饰器时，我希望调用该before_request 。

My code structure is below (not that config.py is simply my SQL connection):我的代码结构如下（不是那个config.py只是我的 SQL 连接）：

application.py应用程序.py

from dash.dependencies import Input, Output, State
import dash_core_components as dcc
import dash_html_components as html

from server import app, server as application, User, login_manager
from flask_login import logout_user, current_user, login_user, login_required
from flask import session, redirect, render_template, url_for, request
from views import main

app.layout = html.Div([

    dcc.Location(id='url', refresh=False),

    html.Div(id='page-content')

])

@application.route('/login')
def login():

    return render_template('login.html')

@application.route('/login', methods=['POST'])
def login_post():
    
    if current_user.is_authenticated:

        return redirect('/dashapp')

    user = User.query.filter_by(username=request.form['username']).first()

    #Check if user exists
    if user:

        #Check if password is correct
        if user.password==request.form['password']:

            login_user(user, remember=False)
            return redirect('/dashapp')

@login_manager.unauthorized_handler
def unauthorized():
    
    if request.path!='/login':
        return redirect('/login')

@application.route('/logout')
@login_required
def logout():

    logout_user()
    return redirect('/login')

@application.route('/dashapp')
@login_required
def main_page():

    return app.index()

@app.callback(
    Output('page-content', 'children'),
    [Input('url', 'pathname')])
def display_page(pathname):

    if current_user.is_authenticated:
        content = main.get_layout()
    else:
        content = dcc.Location(pathname='/login', id='redirect-id')

    return content

if __name__ == '__main__':
    app.run_server()

views/login.html视图/登录.html

<html>
  <head>
    <title>Flask Intro - login page</title>
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link href="static/bootstrap.min.css" rel="stylesheet" media="screen">
  </head>
  <body>
    <div class="container">
      <h1>Please login</h1>
      <br>
      <form action="" method="post">
        <input type="text" placeholder="Username" name="username" value="{{
          request.form.username }}">
         <input type="password" placeholder="Password" name="password" value="{{
          request.form.password }}">
        <input class="btn btn-default" type="submit" value="Login">
      </form>
      {% if error %}
        <p class="error"><strong>Error:</strong> {{ error }}
      {% endif %}
    </div>
  </body>
</html>

server.py服务器.py

import dash, os, datetime
from flask_login import LoginManager, UserMixin, current_user, login_required
from config import connection_string
import dash_bootstrap_components as dbc
from credentials import db, User as base
from flask import session, g, redirect, url_for, request, flash, render_template
import flask

external_stylesheets = [dbc.themes.BOOTSTRAP]

app_flask = flask.Flask(__name__)

app = dash.Dash(
    __name__,
    server=app_flask,
    external_stylesheets=external_stylesheets,
    update_title=None,
    url_base_pathname='/'
)

app.title = 'Login Testing Interface'
server = app_flask
app.config.suppress_callback_exceptions = True

server.config.update(
    SECRET_KEY=os.urandom(12),
    SQLALCHEMY_DATABASE_URI=connection_string,
    SQLALCHEMY_TRACK_MODIFICATIONS=False
)

db.init_app(server)

#Setup the LoginManager for the server
login_manager = LoginManager()
login_manager.init_app(server)
login_manager.login_view = 'login'

#Create User class with UserMixin
class User(UserMixin, base):

    def get_id(self):

        return self.user_id

#Reload the user object
@login_manager.user_loader
def load_user(user_id):

    return User.query.get(user_id)

@server.before_request
@login_required
def check_authentication():

    session.permanent = True
    server.permanent_session_lifetime = datetime.timedelta(seconds=5)
    session.modified = True
    g.user = current_user

main.py主文件

from dash.dependencies import Input, Output, State
import dash_core_components as dcc
import dash_html_components as html
import dash_bootstrap_components as dbc

from flask_login import current_user

from server import app, server

def get_layout():

    return html.Div([

        dcc.Location(id='url-main', refresh=False),

        dbc.Button('Click me', id='test-click', n_clicks_timestamp=0),

        html.Div(id='testing')

    ])

@app.callback(
    Output('testing', 'children'),
    [Input('test-click', 'n_clicks_timestamp')])
def update_test_div(clicks):

    return f'Last clicked: {clicks}'

credentials.py凭证.py

from flask_sqlalchemy import SQLAlchemy
from config import engine

db = SQLAlchemy()

db.Model.metadata.reflect(engine)

class User(db.Model):

    __table__ = db.Model.metadata.tables['my_sql_table_with_user_details']

Thank you in advance for any guidance here!在此先感谢您的任何指导！

Answer 1

I suggest writing your login and login post route as a single fuunction我建议将您的登录和登录后路由写为单个功能

@app.route('/login', methods=['POST','GET'])
def login():
    if current_user.is_authenticated :
        return redirect('/')
    if request.method == 'POST':
        user_name = request.form.get('username')
        password_entered =request.form.get('password')
        
        present_user=User.query.filter_by(username=user_name).first()
        if present_user.password == password_entered:
            login_user(present_user)
            next_page= request.args.get('next')
            print(next_page)
            return redirect(next_page)  if next_page else redirect('/')
        else:
            flash('Incorrect  Password',category='danger')
            return render_template('user_login.html')
    else:
        return render_template('user_login.html')

If you redirected from the login_required function to the Login page, you might notice that the link /url on top says如果您从login_required函数重定向到登录页面，您可能会注意到顶部的 /url 链接说

/login?next=%2FpathofFunction /login?next=%2FpathofFunction

When we write当我们写

next_page= request.args.get('next') next_page= request.args.get('next')

We get the remaining URL after ?next and then redirect the user to where it came from我们在 ?next 之后得到剩余的 URL，然后将用户重定向到它来自的位置

Flask-Login @login-required 装饰器在会话过期后不会重定向到登录页面

问题描述

1 个解决方案

解决方案1
1 2020-11-22 04:37:51

Flask-Login @login-required 装饰器在会话过期后不会重定向到登录页面

问题描述

1 个解决方案

解决方案1 1 2020-11-22 04:37:51

解决方案1
1 2020-11-22 04:37:51