Show custom fields

product.html

{{ form_open('cart/add_to_cart', {'class': 'buy-btn-form'}, {'id': product.id, 'variant_id': '', 'cartkey': cart('cartkey')}) }}

    {% for option in options %}
        {% if option.id in product.available_options %}
            {% if option.type == 'textarea' %}
                <label>{{ option.name }}</label>
                <textarea class="form-control" name="option[{{ option.id }}]"></textarea>
            {% elseif option.type == 'textfield' %}
                <label>{{ option.name }}</label>
                <input class="form-control" name="option[{{ option.id }}]">
            {% endif %}
        {% endif %}
    {% endfor %}
    
    .......

{{ form_close() }}