python - 登录到我的 Flask 应用程序后，如何显示注销而不是登录/注册？

Question

我使用 Flask 和 Jinja 模板创建了一个网站。我已经创建了登录和注册表单。在我的主页的标题中，有注册和登录。登录后我想用注销替换登录/注册。如果有什么解决办法请告诉我。这将会非常有帮助。提前致谢。代码如下。

index.html

<nav class="navbar navbar-inverse navbar-fixed-top" style="background-color: 

    white; border-bottom: #dddddd solid 1px;border-top: none;border-left: none;border-right: none;">
        <div class="container-fluid">
          <div class="navbar-header">
            <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#myNavbar">
              <span class="icon-bar"></span>
              <span class="icon-bar"></span>
              <span class="icon-bar"></span> 
            </button>
            <a class="navbar-brand" href="#" style="padding: 10px 20px;margin: 20px 0;">WebSiteName</a>
          </div>
          <div class="collapse navbar-collapse" id="myNavbar">
            <!--ul class="nav navbar-nav">
              <li class="active"><a href="#">Home</a></li>
              <li><a href="#"></a></li>
              <li><a href="#">Page 2</a></li> 
              <li><a href="#">Page 3</a></li> 
            </ul-->
            <ul class="nav navbar-nav navbar-right ul1">
              <li class="li1"><a id="a1" style="color: red;" href="{{ url_for('index') }}">Home</a></li>
          <li class="li1"><a id="a1" href="{{ url_for('.index', _anchor='about') }}">About Product</a></li>
          <li class="li1"><a id="a1" href="{{ url_for('.index', _anchor='foot') }}">Contact Us</a></li>
          {% if is_authenticated == 'true' %}
          <li class="li1"><a id="a1" href="{{ url_for('logout') }}">Logout</a></li>
          {% else %}
          <li class="li1"><a id="a1" href="{{ url_for('signup') }}">Signup</a></li>
          <li class="li1"><a id="a1" href="{{ url_for('login') }}">Login</a></li>
          {% endif %}
              <!--li><a href="#"><span class="glyphicon glyphicon-user"></span> Sign Up</a></li>
              <li><a href="#"><span class="glyphicon glyphicon-log-in"></span> Login</a></li-->
            </ul>
          </div>
        </div>
      </nav>

应用程序.py

from flask import Flask, render_template, redirect, url_for, flash
from flask_bootstrap import Bootstrap
from flask_wtf import FlaskForm 
from wtforms import StringField, PasswordField, BooleanField
from wtforms.validators import InputRequired, Email, Length
from flask_sqlalchemy  import SQLAlchemy
from werkzeug.security import generate_password_hash, check_password_hash
from flask_login import LoginManager, UserMixin, login_user, login_required, logout_user, current_user

app = Flask(__name__)
app.config['SECRET_KEY'] = 'Thisissupposedtobesecret!'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///database.db'
Bootstrap(app)
db = SQLAlchemy(app)
login_manager = LoginManager()
login_manager.init_app(app)
login_manager.login_view = 'login'

class User(UserMixin, db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(15), unique=True)
    email = db.Column(db.String(50), unique=True)
    password = db.Column(db.String(80))

    def is_authenticated(self):
        """Return True if the user is authenticated."""
        return self.authenticated

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

class LoginForm(FlaskForm):
    username = StringField('Username', validators=[InputRequired(), Length(min=4, max=15)])
    password = PasswordField('Password', validators=[InputRequired(), Length(min=8, max=80)])
    remember = BooleanField('Remember me')

class RegisterForm(FlaskForm):
    email = StringField('Email', validators=[InputRequired(), Email(message='Invalid email'), Length(max=50)])
    username = StringField('Username', validators=[InputRequired(), Length(min=4, max=15)])
    password = PasswordField('Password', validators=[InputRequired(), Length(min=8, max=80)])

@app.route('/')
def index():
    return render_template('index.html')

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

    if form.validate_on_submit():
        user = User.query.filter_by(username=form.username.data).first()
        if user:
            if check_password_hash(user.password, form.password.data):
                login_user(user, remember=form.remember.data)
                return redirect(url_for('dashboard'))

        return '<h1>Invalid username or password</h1>'
        #return '<h1>' + form.username.data + ' ' + form.password.data + '</h1>'

    return render_template('login.html', form=form)

@app.route('/signup', methods=['GET', 'POST'])
def signup():
    form = RegisterForm()

    if form.validate_on_submit():
        hashed_password = generate_password_hash(form.password.data, method='sha256')
        new_user = User(username=form.username.data, email=form.email.data, password=hashed_password)
        db.session.add(new_user)
        db.session.commit()
        flash('User successfully registered')
        return redirect(url_for('login'))
        #return '<h1>' + form.username.data + ' ' + form.email.data + ' ' + form.password.data + '</h1>'


    return render_template('signup.html', form=form)

@app.route('/dashboard')
@login_required
def dashboard():
    return render_template('dashboard.html', name=current_user.username)

@app.route('/logout')
@login_required
def logout():
    logout_user()
    return redirect(url_for('index'))

if __name__ == '__main__':
    app.run(debug=True)

Answer 1

只需在模板中使用 Flask-login 中的内置 current_user 即可，如下所示:

{% if current_user.is_authenticated %}
-- place logout button here --
{% else %}
-- place login button here --
{% endif %}