Adapt a view if an app is installed with Django

Question

I have a web app with a project that works alone (it's index, login.. pages).

I would need to change the index page if a new app is installed (e.g: add a link, a table in the template with my app models..). Have it dynamic.

The removal of the app must let the project intact and just remove the link.

How can I do that? Is it possible?

score 15 · Answer 1 · answered Apr 03 '17 at 16:38

You can use the Django's application registry:

In [1]: from django.apps import apps
In [2]: apps.is_installed("django.contrib.admin")
Out[2]: True

An application can actually be enabled by using a dotted Python path to either its package or the application's configuration class (preferred). Simply checking if "app_name" is in settings.INSTALLED_APPS will fail in the latter case.

scytale · Accepted Answer · 2012-07-17T13:11:02.777

5

def my_view(request):
    from django.conf import settings
    app_installed = 'app_name' in settings.INSTALLED_APPS

    return render_to_response(template_name, {'app_installed': app_installed})

template:

{% if app_installed %}
    ...
{% endif %}

edited Jul 17 '12 at 13:11

answered Jul 17 '12 at 13:03

scytale

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1

This will fail if the application was enabled using an application configuration class. It's better to [use the application registry](http://stackoverflow.com/a/43189917/244297). – Eugene Yarmash Apr 03 '17 at 16:44
1

The docs say _Your code should never access `INSTALLED_APPS` directly. Use `django.apps.apps` instead._ https://docs.djangoproject.com/en/3.0/ref/settings/#std:setting-INSTALLED_APPS – Michael Scheper Feb 18 '20 at 03:47

score 5 · Answer 3 · answered Apr 08 '16 at 16:58

Or use a custom context processor.

In installed_apps.py

from django.conf import settings

def installed_apps(request):
    return {
       'app_installed' : 'app_name' in settings.INSTALLED_APPS
    }

In settings.py:

TEMPLATE_CONTEXT_PROCESSORS = (
    ...
    'installed_apps.installed_apps'
)

score 1 · Answer 4 · answered May 21 '18 at 14:34

simple_tag version:

The tricky part is that you can't pass arguments to your simple_tag when it's used in a conditional. Therefor, you create a new variable specifically for your installed app with as is_myapp_installed.

In templatetags/my_filters.py:

from django import template
register = template.Library()

@register.simple_tag
def is_app_installed(app):
  from django.apps import apps
  return apps.is_installed(app)

In template:

{% load my_filters %}
   ...
{% is_app_installed "myapp" as is_myapp_installed %}    
{% if is_myapp_installed %}
   ...
{% endif %}

Adapt a view if an app is installed with Django

4 Answers4