How it works

Added in 1.0.1

Chassis is a thin assembly layer over Django Admin. You declare capabilities. Services turn those declarations into URLs, template context, and permission checks. Templates and static files render the result.

Two mixins

The public entry points are ChassisAdminSiteMixin and ChassisAdminMixin.

ChassisAdminSiteMixin + AdminSite
  ├── dashboard_component_classes / dashboard_blocks → DashboardService
  ├── navbar_button_classes / user_menu_item_classes → AdminNavbarService
  ├── chassis_page_classes → AdminPageService
  ├── sidebar_items → AdminSidebarService
  └── wraps third-party ModelAdmin classes in ChassisAdminMixin

ChassisAdminMixin + ModelAdmin
  └── options: list[AdminOption]
        ├── SearchOption, FiltersOption, DateHierarchyOption, tabs
        ├── RowActionsOption, ListActionsOption, ObjectActionsOption
        ├── RelatedFieldsOption, RelatedEntitiesOption
        └── ImportOption, ExportOption

Both mixins must precede the Django class in the MRO so their hooks can wrap super().

Internal ModelAdmin composition

django_chassis.mixins.admin remains the public module for ChassisAdminMixin. Its implementation is assembled from focused classes in django_chassis.mixins.core:

AdminCoreMixin — shared options and typed access to the next ModelAdmin
AdminPermissionsMixin and AdminAuditMixin — access and CRUD audit hooks
AdminChangeListMixin and AdminObjectPageMixin — list and object pages
AdminActionsMixin and AdminImportExportMixin — actions and data flows
AdminPresentationMixin — dynamic fields, columns, and widgets

These classes are implementation parts. Applications continue to inherit only ChassisAdminMixin; its public import paths and position in the application MRO do not change.

Model managers

Django model Manager and QuerySet classes live in django_chassis.models.managers. Model modules contain model declarations and attach the imported manager; they do not define query infrastructure inline.

Frozen options

A ModelAdmin does not subclass a dozen mixins for search, badges, and export. It appends frozen dataclasses to options. ChassisAdminMixin looks up each type, applies it to Django Admin attributes (search_fields, list_filter, …), and feeds the rest to templates.

Missing option types fall back to the mixin default. Today that default is RowActionsOption() — a view button on every changelist.

Settings is not an AdminOption. It is a separate dataclass on chassis_settings for collapsed fieldsets and whether the standard add button is shown.

Services

Site-level work is not done in views. The site constructs services:

Service	Responsibility
`DashboardService`	Component registry, layout validation, SSR context, live JSON
`AdminNavbarService`	Theme item, custom buttons, page groups, user menu
`AdminPageService`	Page routes and navbar/dashboard groups
`AdminSidebarService`	Resolve model/page references, permissions, active state

You can replace a service class on the site (dashboard_service_class, …) or override get_*_service().

Request path

Django routes the request to the Chassis AdminSite.
each_context injects brand, sidebar, navbar, and footer into every Admin template.
Index (/): DashboardService maps dashboard_blocks onto component slugs and renders admin/chassis/dashboard/index.html. Live widgets poll dashboard/live/ with If-None-Match.
Changelist: ChassisAdminMixin.changelist_view reads options, builds tabs / search / filters / list actions, and renders admin/chassis/change_list.html.
Change form: changeform_view adds object-action buttons and related entity tables (admin/chassis/change_form.html).
Custom page: AdminPage.dispatch checks the access contract, then view() / render().
Object action / import / export: extra URLs from ChassisAdminMixin.get_urls().

A missing option type is not an error. The mixin uses the class-level default (RowActionsOption()) or skips that chrome (no search fieldset without SearchOption).

Templates

'django_chassis' must sit before 'django.contrib.admin' in INSTALLED_APPS. Chassis ships a full overlay of Admin templates plus a parallel admin/tabler/ family. Domain apps should not copy those templates.

See Theming.

What Chassis does not do

It does not own your models.
It does not replace Django permissions; it checks them.
It does not invent a new admin URL scheme. Custom pages and dashboard actions are extra routes on the same AdminSite.

Two mixins​

Internal ModelAdmin composition​

Model managers​

Frozen options​

Services​

Request path​

Templates​

What Chassis does not do​

See also​