How do I use 'is not None' in Django Templates?

Question

I want to customize the greeting on my homepage so it's whether:

When logged in and entered first name:

John! Where do you want to go?

else:

Where do you want to go?

This is my template:

 {% if user.is_authenticated and not firstname_of_logged_user == None%}
 <h1 class="text-center" id="extraglow">{{firstname_of_logged_user}}! where do 
 you want to go?</h1></label>
{%else%}
<h1 class="text-center" id="extraglow">where do you want to go?</h1></label>
                                {%endif%}

However, it doesn't seem to pick up the "not None" part because if the user is logged in but didn't enter first name it shows like this:

! where do you want to go?

and if I say:

firstname_of_logged_user is not None

it says an error:

Unused 'is' at end of if expression.

Seems like an easy thing but it's not working. What's wrong? Cheers!

Answer 1

The if template tag has supported the is operator since Django 1.10 (release notes).

You can now do {% if x is None %} and {% if x is not None %}.

Answer 2

You can use the != operator instead of not. However, things can be simplified even further to:

{% if user.is_authenticated and firstname_of_logged_user %}

The above will check whether or not firstname_of_logged_user is truthy in your template.

Answer 3

The is operator is not supported. Just use {% if var != None %}. This is not exactly the same but it will be sufficient for most cases.

See supported operators here.

If you actually want to use the is operator, you would have to implement it as a custom template tag.

For instance:

@register.filter(name='is')
def do_is(lhs, rhs):
    return lhs is rhs

Thus you will be able to use it as:

{% if var1|is:var2 or not var3|is:var4 %}
    ...
{% else %}
    ...
{% endif %}