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Debugging 405 Method Not Allowed in Django Nominopolitan Bulk Actions

The Problem: 405 on Toggle All Selection

When attempting to use the "toggle all selection" checkbox in the Django Nominopolitan list view, a 405 Method Not Allowed error was encountered for the POST request to /sample/bigbook/toggle-all-selection/. This indicated that while the URL was being matched, the HTTP POST method was not permitted for the associated view.

Initial Investigation & The "Pretence"

The JavaScript frontend correctly sends a POST request. The Django URL configuration in nominopolitan/mixins/url_mixin.py for this endpoint explicitly included http_method_names=["post"]:

path(
    f"{cls.url_base}/toggle-all-selection/",
    cls.as_view(
        role=Role.LIST, # The "pretence"
        http_method_names=["post"],
        template_name_suffix="_toggle_all_selection",
    ),
    name=f"{cls.url_base}-toggle-all-selection",
)

The toggle_all_selection_view method in nominopolitan/mixins/bulk_mixin.py was the intended handler. However, debug messages from this view were not appearing, suggesting the view method itself was never reached.

The core issue stemmed from the role=Role.LIST assignment. While seemingly logical (as the action relates to the list view), neapolitan's Role.LIST enum is designed to handle GET requests for listing ({"get": "list"}). It does not define a POST handler.

The Flow of Failure

  1. Frontend (JavaScript): Sends POST request to /sample/bigbook/toggle-all-selection/.
  2. Django URL Dispatcher: Matches the URL to the path defined in UrlMixin.get_urls.
  3. neapolitan.views.CRUDView.as_view():
    • Receives role=Role.LIST.
    • Consults Role.LIST.handlers(), which only specifies {"get": "list"}.
    • Dynamically sets self.get = self.list on the view instance.
    • Crucially, it does NOT set self.post because Role.LIST.handlers() lacks a post entry. The http_method_names=["post"] parameter is noted by Django's generic View but doesn't override neapolitan's Role-based method mapping.
  4. CRUDView.dispatch():
    • Receives the POST request.
    • Checks for a self.post method.
    • Finds no self.post method (as it was never set by as_view() for Role.LIST).
    • Returns 405 Method Not Allowed.

The toggle_all_selection_view method is never executed because the request is rejected at the dispatch level.

The Solution: Speaking neapolitan's Language

The neapolitan framework provides a clear pattern for extending its functionality with custom actions, as demonstrated by BulkEditRole. Instead of trying to force custom POST actions into existing Role enums (like Role.LIST) that don't have POST handlers, the solution is to define dedicated "Role-like" objects for these custom actions.

We implemented the Single Enum for Core Bulk Actions approach. We created a new enum called BulkActions in nominopolitan/mixins/bulk_mixin.py. This enum has members for each bulk action (TOGGLE_SELECTION, CLEAR_SELECTION, TOGGLE_ALL_SELECTION). Each enum member defines its own handlers() and URL patterns, similar to how neapolitan.Role itself is structured.

This solution ensures that neapolitan's as_view method receives a role object that correctly defines a POST handler for the specific action, allowing the dispatch method to route the request to the intended view function and resolve the 405 error. This adheres to the framework's design philosophy, leading to more maintainable and robust code.