Jinja2 template variable if None Object set a default value

How to make a variable in jijna2 default to “” if object is None instead of doing something like this?

      {% if p %}   
        {{ p.User['first_name']}}
      {% else %}
        NONE
      {%endif %}

So if object p is None I want to default the values of p (first_name and last_name) to “”.
Basically

nvl(p.User[first_name'], "")

Error receiving:

Error:  jinja2.exceptions.UndefinedError
    UndefinedError: 'None' has no attribute 'User'