How to customize collection element in symfony2 forms

Question

I have a simple form related to a user in which i'm adding a collection of phone numbers (another form).

I can get it working with javascript but i want to customize the rendering of each phone input.

The same thing is working with a simple field by doing this :

{% block _elementId_widget %}
    {{ block('form_widget_simple') }}
    <input type="button" class="btn" id="btnInvertNames" value="{{ "form.invertNames"|trans }}" />
{% endblock %}

To add a button after the widget, but not working with collections..

Answer 1

A solution i found is to write a new "Form Type" and to customize its template :

Look here for documentation