Message Flashing

Flask provides a really simple way to give feedback to a user with the flashing system.

1. In index.html, add below block:

   
    {% with messages = get_flashed_messages() %}
      {% if messages %}
        <div class="alert alert-danger">
        <ul class=flashes>
        {% for message in messages %}
          <li>{{ message }}</li>
        {% endfor %}
        </ul>
        </div>
      {% endif %}
    {% endwith %}
   

2. In views.py, add flash messages:

@weather.route('/update/<location>', methods=['POST', 'GET'])
def update(location):
    form = UpdateForm()
    if form.validate_on_submit():
        ....
        flash('The weather is successfully updated.')
        return render_template('update.html', form=form, dt=dt,basic=basic, detail=detail, daily=daily.daily_list, alert=False)
    else:
        flash('Can not find the location in your search history. Please go back to index page, search the location first, then update if the data are wrong!')
        return render_template('update.html', form=form, alert=True)