Django templates: If false?

Question

How do I check if a variable is False using Django template syntax?

{% if myvar == False %}

Doesn\'t seem to work.

Answer 1

In old version you can only use the ifequal or ifnotequal

{% ifequal YourVariable ExpectValue %}
    # Do something here.
{% endifequal %}

Example:

{% ifequal userid 1 %}
  Hello No.1
{% endifequal %}

{% ifnotequal username 'django' %}
  You are not django!
{% else %}
  Hi django!
{% endifnotequal %}

As in the if tag, an {% else %} clause is optional.

The arguments can be hard-coded strings, so the following is valid:

{% ifequal user.username "adrian" %} ... {% endifequal %} An alternative to the ifequal tag is to use the if tag and the == operator.

ifnotequal Just like ifequal, except it tests that the two arguments are not equal.

An alternative to the ifnotequal tag is to use the if tag and the != operator.

However, now we can use if/else easily

{% if somevar >= 1 %}
{% endif %}

{% if "bc" in "abcdef" %}
  This appears since "bc" is a substring of "abcdef"
{% endif %}

Complex expressions

All of the above can be combined to form complex expressions. For such expressions, it can be important to know how the operators are grouped when the expression is evaluated - that is, the precedence rules. The precedence of the operators, from lowest to highest, is as follows:

• or
• and
• not
• in
• ==, !=, <, >, <=, >=

More detail

https://docs.djangoproject.com/en/dev/ref/templates/builtins/

Answer 2

Look at the yesno helper

Eg:

{{ myValue|yesno:"itwasTrue,itWasFalse,itWasNone" }}

Answer 3

Just ran into this again (certain I had before and came up with a less-than-satisfying solution).

For a tri-state boolean semantic (for example, using models.NullBooleanField), this works well:

{% if test.passed|lower == 'false' %} ... {% endif %}

Or if you prefer getting excited over the whole thing...

{% if test.passed|upper == 'FALSE' %} ... {% endif %}

Either way, this handles the special condition where you don't care about the None (evaluating to False in the if block) or True case.

Answer 4

You could write a custom template filter to do this in a half-dozen lines of code:

from django.template import Library

register = Library()

@register.filter
def is_false(arg): 
    return arg is False

Then in your template:

{% if myvar|is_false %}...{% endif %}

Of course, you could make that template tag much more generic... but this suits your needs specifically ;-)