{% if user.is_authenticated %}
<span class="user_name">{{ user.username }}</span> | 
<a href='{% url logout %}?next={{request.get_full_path}}'>Wyloguj</a>
{% else %}
{% url login as login_url %}
{% ifnotequal login_url request.path %}
    <a href='{{ login_url }}?next={{request.get_full_path}}'>Logowanie</a>
{% endifnotequal %}

{% endif %}