{{ form_start(form) }}
<div class="row">
<div class="col-md-12">
{{ form_widget(form) }}
</div>
</div>
<br/>
<div class="row">
<div class="col-md-12">
<button class="btn btn-primary">{{ button_label|default('Save') }}</button>
</div>
</div>
<br/>
{{ form_end(form) }}