_forms.html

{% macro render(form) -%}

<fieldset>
{% for field in form %}
{% if field.type in ['CSRFTokenField', 'HiddenField'] %}
  {{ field() }}
{% else %}
  <div class="clearfix {% if field.errors %}error{% endif %}">
    {{ field.label }}
    <div class="input">
      {% if field.name == "body" %}
        {{ field(rows=10, cols=40) }}
      {% else %}
        {{ field() }}
      {% endif %}
      {% if field.errors or field.help_text %}
        <span class="help-inline">
        {% if field.errors %}
          {{ field.errors|join(' ') }}
        {% else %}
          {{ field.help_text }}
        {% endif %}
        </span>
      {% endif %}
    </div>
  </div>
{% endif %}
{% endfor %}
</fieldset>
{% endmacro %}

book_form.html

{% import '_forms.html' as forms %}

<!-- ... -->

{% block form %}
<section>
  <h1>{{ action }} {{ data_type }}</h1>
  <form action="{{ form_action }}" method="{{ method | d("POST") }}">
    {{ forms.render(form) }}
    <input type="submit" value="Submit">
  </form>
</section>
{% endblock form %}