Django Expressions

Django template tag and filter for evaluating Python expressions.

Demo

As a template tag {% expr "<expression>" %}

{% expr "[a for a in range(n)]" %}

Save the result to a variable using as var at the end of the tag:

{% expr "[a for a in range(n)]" as result %}
{{ result }}

As a filter "<expression>" | expr:

{{ "{k: v.name for k, v in employees_dict.values() }" | expr }}

To chain an expression after another filter, define a lambda expression as the filter argument value | expr:"lambda x: <expression>":

{{ employees_list | first | expr:"lambda x: x.first_name + ' ' + x.last_name" }}

Installation

1. Install dependencies

   pip install django_expr
   

2. Add django_expr to INSTALLED_APPS in your settings.py

   INSTALLED_APPS = [
       "django_expr",
       ...
   ]
   

3. Inside templates, load the tags with {% load expr %}:

   {% load expr %}
   {% expr "[{k: not v} for k, v in ({'a': 'b', 'c': 0}).items()]" %}
   

4. If you want to automatically include the expr tag and filter, add the tags as a 'builtin' in settings.py:

TEMPLATES = [
    {
        ...,
        'OPTIONS': {
            'context_processors': [
                ...
            ],
            'builtins': [
                'django_expr.templatetags.expr',
            ]
        },
    },
]