{% for message in app.flashes('danger') %}
    <div class="alert alert-danger alert-dismissible fade show" role="alert">
        {{ message }}
        <button type="button" class="close" data-dismiss="alert" aria-label="Close">
            <span aria-hidden="true">&times;</span>
        </button>
    </div>
{% endfor %}

{{ form_start(form) }}
    {{ form_row(form.name) }}
    <button class="btn btn-info">{{ button | default('Valider') }}</button>
{{ form_end(form) }}