This code was floating around in a pastebin, and was linked to me from IRC. I’m not sure who originally wrote it, but it’s useful and I wanted to make sure it gets saved so that it can eventually be the basis of a Symfony2 cookbook article.

[code lang="php"]{% block collection_widget %}
{% spaceless %}
<div class="collection">
{% if prototype is defined %}
{% set attr = attr|merge({'data-prototype': block('collection_item_widget') }) %}
{% endif %}
<div {{ block('widget_container_attributes') }}>
{{ form_errors(form) }}
<ul>
{% for rows in form %}
<li>
{% set fieldNum = 1 %}
{% for row in rows %}
<div class="field{{ fieldNum }}">
{{ form_label(row) }}
{{ form_widget(row, { 'attr': { 'class': 'test' }}) }}
</div>
{% set fieldNum = fieldNum + 1 %}
{% endfor %}
<a class="remove" title="Remove" href="javascript:void()">
<span>Delete</span>
</a>
<div class="clear"></div>
</li>
{% endfor %}
</ul>
{{ form_rest(form) }}
</div>
<div class="clear"></div>
<a class="add" title="Add" href="javascript:void()">
<div style="display: none;"></div>
<span>Add</span>
</a>
</div>
<div class="clear"></div>
{% endspaceless %}
{% endblock collection_widget %}

{% block collection_item_widget %}
{% spaceless %}
<li>
{% set fieldNum = 1 %}
{% for row in prototype %}
<div class="field{{ fieldNum }}">
{{ form_label(row) }}
{{ form_widget(row, { 'attr': { 'class': 'test' }}) }}
</div>
{% set fieldNum = fieldNum + 1 %}
{% endfor %}
<a class="remove" title="Remove" href="javascript:void()">
<span>Delete</span>
</a>
<div class="clear"></div>
</li>
{% endspaceless %}
{% endblock collection_item_widget %}[/code]

Also, here’s a github gist link to the same code.