Flask之闪现flash原理及使用

# -*- coding: utf-8 -*-
from flask import Flask, flash, redirect, render_template, request, url_for

app = Flask(__name__)
app.secret_key = 'GuHanZheIsCool'      # 使用闪现必须设置secret_key哦~文末讲了原因。

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


@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        # Perform login validation
        username = request.form.get('username')
        password = request.form.get('password')

        if username == 'admin' and password == 'GuHanZhe':
            flash('Login successful!', 'success')
            return redirect(url_for('index'))
        else:
            flash('Invalid credentials!', 'error')

    return render_template('login.html')


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

<!-- index.html -->
{% with messages = get_flashed_messages() %}
    {% if messages %}
        <ul class="messages">
            {% for message in messages %}
                <li>{{ message }}</li>
            {% endfor %}
        </ul>
    {% endif %}
{% endwith %}



<!-- login.html -->
<form action="{{ url_for('login') }}" method="POST">
    {% with messages = get_flashed_messages(category_filter=['error']) %}
    {% if messages %}
    <ul class="errors">
        {% for message in messages %}
        <li>{{ message }}</li>
        {% endfor %}
    </ul>
    {% endif %}
    {% endwith %}

    <!-- Form fields -->
    <input type="text" name="username"><br>
    <input type="text" name="password"><br>
    <button type="submit">Login</button>
</form>

from flask import Flask, session

app = Flask(__name__)
app.secret_key = 'GuHanZheIsCool'


@app.route('/x1')
def view_x1():
    session['msg'] = '孤寒者真帅~'
    return '视图函数x1'


@app.route('/x2')
def view_x2():
    msg = session.pop('msg')
    print(msg)
    return '视图函数x2'


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