{% load i18n %}
{% load template_filters %}

<a class="button blue icon-calendar {% if obj|in_calendar:request.user %}removecalendar {% else %}addcalendar {% endif %}" href="{{ obj.get_calendar_url }}">{% if obj|in_calendar:request.user %}{% trans 'Из расписания' %}{% else %}{% trans 'В расписание' %}{% endif %}</a>