传递数据

# ... 
# same as above

@app.route('/welcome/<name>')
def welcome(name):
    return render_template('main.html', name=name)

@app.route('/login', methods=['GET', 'POST'])
def login():
    if request.method == 'POST':
        # ...
        # check for valid login, assign username
        if valid:
            return redirect(url_for('main_page', name=username))
        else:
            return redirect(url_for('login_error'))
    else:
        return render_template('login.html')