Django ExtendedActionsMixin allows ModelAdmin classes to execute actions with empty queryset and filtered queryset

README.md

ExtendedActionsMixin

This is a Django mixin that allows ModelAdmin classes to execute actions without selecting any objects on the change list of the Django Admin.

To implement it you need to include the Mixin as usual (see https://docs.djangoproject.com/en/1.10/topics/class-based-views/mixins/) and define a class attribute called extended_actions containing a list of string with the name of the actions that you want to be exectued with empty queryset.

If in the action you want to use the same queryset that the user is seeing, you can use the get_filtered_queryset method also provided by the mixin

Example:

@admin.register(Contact)
class ContactAdmin(ExtendedActionsMixin, admin.ModelAdmin):
    list_display = ('name', 'country', 'state')
    actions = ('export',)
    extended_actions = ('export',)
    
    def export(self, request, queryset):
        if not queryset:
            # if not queryset use the queryset filtered by the URL parameters
            queryset = self.get_filtered_queryset(request)

        # As usual do something with the queryset

admin.py

class ExtendedActionsMixin:
    # actions that can be executed with no items selected on the admin change list.
    # The filtered queryset displayed to the user will be used instead
    extended_actions = []

    def changelist_view(self, request, extra_context=None):
        # if a extended action is called and there's no checkbox selected, select one with
        # invalid id, to get an empty queryset
        if "action" in request.POST and request.POST["action"] in self.extended_actions:
            if not request.POST.getlist(admin.helpers.ACTION_CHECKBOX_NAME):
                post = request.POST.copy()
                post.update({admin.helpers.ACTION_CHECKBOX_NAME: 0})
                request._set_post(post)  # pylint:disable=protected-access
        return super().changelist_view(request, extra_context)

    def get_changelist_instance(self, request):
        """
        Returns a simple ChangeList view instance of the current ModelView.
        (It's a simple instance since we don't populate the actions and list filter
        as expected since those are not used by this class)
        """
        list_display = self.get_list_display(request)
        list_display_links = self.get_list_display_links(request, list_display)
        list_filter = self.get_list_filter(request)
        search_fields = self.get_search_fields(request)
        list_select_related = self.get_list_select_related(request)

        change_list = self.get_changelist(request)

        return change_list(
            request,
            self.model,
            list_display,
            list_display_links,
            list_filter,
            self.date_hierarchy,
            search_fields,
            list_select_related,
            self.list_per_page,
            self.list_max_show_all,
            self.list_editable,
            self,
            self.sortable_by,
        )

    def get_filtered_queryset(self, request):
        """
        Returns a queryset filtered by the URLs parameters
        """
        change_list = self.get_changelist_instance(request)
        return change_list.get_queryset(request)
        

        return change_list(
            request,
            self.model,
            list_display,
            list_display_links,
            list_filter,
            self.date_hierarchy,
            search_fields,
            list_select_related,
            self.list_per_page,
            self.list_max_show_all,
            self.list_editable,
            self,
            self.sortable_by,
            self.search_help_text,  ### <- Here the new line
        )