How to render dynamic or responsive form fields using form type symfony?

Question

I have five data entries from database, mapset` that I render in twig:

 {{ form_start(form) }}
    {% for item in mapset %}
       <tr> 
         <td>{{ item.name }}</td>
         <td>{{ form_widget(form.sets) }}</td>
         <td>{{ form_widget(form.options) }}</td>
         <td>{{ form_widget(form.buttonSet) }}</td>
         <td>{{ form_widget(form.buttonItem) }}</td>
       </tr>
    {% endfor %}
  {{ form_end(form) }}

This form should render a total of 20 inputs that would look like this:

  name1  [] [] [] []
  name2  [] [] [] []
  name3  [] [] [] []
  name4  [] [] [] []
  name5  [] [] [] []

but my codes shows:

 name1  [] [] [] []
 name2
 name3
 name4
 name5

I've read a lot about dynamic form and form collection but I don't get it.

Answer 1

{# src/AppBundle/Resources/views/Task/new.html.twig #}

{# ... #}

{{ form_start(form) }}
    {# render the task's only field: description #}
    {{ form_row(form.description) }}

    <h3>Tags</h3>
    <ul class="tags">
        {# iterate over each existing tag and render its only field: name #}
        {% for tag in form.tags %}
            <li>{{ form_row(tag.name) }}</li>
        {% endfor %}
    </ul>
{{ form_end(form) }}

{# ... #}

http://symfony.com/doc/2.7/cookbook/form/form_collections.html