How to add custom view to django admin interface?

Problem here that your div is not inside main-content. I suggest extending admin/index.html

Put in app/templates/admin/index.html

{% extends "admin/index.html" %}
{% load i18n static %}

{% block content %}
<div id="content-main">

{% if app_list %}
    {% for app in app_list %}
        <div class="app-{{ app.app_label }} module">
        <table>
        <caption>
            <a href="{{ app.app_url }}" class="section" title="{% blocktrans with name=app.name %}Models in the {{ name }} application{% endblocktrans %}">{{ app.name }}</a>
        </caption>
        {% for model in app.models %}
            <tr class="model-{{ model.object_name|lower }}">
            {% if model.admin_url %}
                <th scope="row"><a href="{{ model.admin_url }}">{{ model.name }}</a></th>
            {% else %}
                <th scope="row">{{ model.name }}</th>
            {% endif %}

            {% if model.add_url %}
                <td><a href="{{ model.add_url }}" class="addlink">{% trans 'Add' %}</a></td>
            {% else %}
                <td>&nbsp;</td>
            {% endif %}

            {% if model.admin_url %}
                {% if model.view_only %}
                <td><a href="{{ model.admin_url }}" class="viewlink">{% trans 'View' %}</a></td>
                {% else %}
                <td><a href="{{ model.admin_url }}" class="changelink">{% trans 'Change' %}</a></td>
                {% endif %}
            {% else %}
                <td>&nbsp;</td>
            {% endif %}
            </tr>
        {% endfor %}
        </table>
        </div>
    {% endfor %}

    <!-- here you could put your div -->
    <div class="app-sonstiges module">
    ....
    </div>
    <!-- here you could put your div -->
{% else %}
    <p>{% trans "You don't have permission to view or edit anything." %}</p>
{% endif %}
</div>
{% endblock %}

The another approach is to add custom app to app_list. But it is far more ugly. So I suggest overriding template.

I assume you are overriding get_urls in AdminSite.

If you need a custom page to handle user input (from form), you may want to give django-etc 1.3.0+ a try:

    from etc.admin import CustomModelPage

    class MyPage(CustomModelPage):
    
        title = 'My custom page'  # set page title

        # Define some fields you want to proccess data from.
        my_field = models.CharField('some title', max_length=10)

        def save(self):
            # Here implement data handling.
            super().save()

    # Register the page within Django admin.
    MyPage.register()

Note: I combined instructions in this answer and this answer:

• Implemented MyAdminSite with get_urls and get_app_list

    def get_urls(self):
        urls = super().get_urls()
        my_urls = [
            path("my-func", self.my_func, name="myfunc"),
        ]
        return my_urls + urls

    def get_app_list(self, request, **kwargs):
        """Show some links in the admin UI.

        See also https://stackoverflow.com/a/56476261"""
        app_list = super().get_app_list(request, kwargs)
        app_list += [
            {
                "name": "Other actions",
                "app_label": "other_actions_app",
                "models": [
                    {
                        "name": "my name",
                        "object_name": "my object name"my_admin:myfunc"),
                        "view_only": True,
                    }
                ],
            }
        ]
        return app_list

• Set admin_site = MyAdminSite(name="my_admin")
• Used @admin.register(MyObject, site=admin_site) with the site parameter but using admin from django.contrib
• Did not change settings (still uses django.contrib.admin)
• Put this line in my overall urls.py to load my registered:

admin_site._registry.update(admin.site._registry)

I know this seems weird, but it's the only thing that really worked for me, so I wanted to write it down in case it's useful for others.

You can add custom URLs to the Django admin by creating a fictitious model, registering it in admin.py, and overriding the get_urls method. You can also create a separate view and add it to the standard urls.py.

1. Create a dummy model (models.py)

Django Admin requires a model to be registered, but you can create a dummy one that won't be saved to the database:

from django.db import models

class DummyModel(models.Model):
    class Meta:
        managed = False

2. Create custom views (views.py)

In this file, we define the functions that will process requests:

from django.http import HttpResponse
from django.contrib.admin.views.decorators import staff_member_required

@staff_member_required
def custom_admin_view(request):
    return HttpResponse("Это кастомная страница в Django Admin.")

3. Add custom URLs to Django Admin (admin.py)

Register a dummy model and override the get_urls method:

from django.contrib import admin
from django.urls import path
from .models import DummyModel
from .views import custom_admin_view

@admin.register(DummyModel)
class CustomAdmin(admin.ModelAdmin):
    def get_urls(self):
        return [path('custom-view/', custom_admin_view, name="yourapp_dummymodel_changelist")]  # name="yourapp_yourmodel_changelist"

The (name="yourapp_yourmodel_changelist") should be specified as I indicated in the comment. This is necessary in order to replace the link on the main page so that View is used when klick on link.

Sorry for my English