Django Admin action with intermediate page example

admin.py

# your_app/admin.py

# ... imports

@admin.register(User)
class UserAdmin(admin.ModelAdmin):
    actions = ['broadcast']  # register method as action
    
    def broadcast(self, request, queryset):
        if 'apply' in request.POST:  # if user pressed 'apply' on intermediate page
            # Cool thing is that params will have the same names as in forms.py
            broadcast_message_text = request.POST["broadcast_text"] 
            bot_id = request.POST["bot"]
            
            # Get data from models using the params - maybe not the best way, sorry
            bot_token = Bot.objects.filter(id=bot_id).first().token
            user_ids = [u.user_id for u in queryset]
            
            # Run background task that will send broadcast messages
            broadcast_message.delay(bot_token, user_ids, broadcast_message_text)
            
            # Show alert that everything is cool
            self.message_user(request, "Broadcasting of %s messages has been started" % len(user_ids))
            
            # Return to previous page
            return HttpResponseRedirect(request.get_full_path())

        # Create form and pass the data which objects were selected before triggering 'broadcast' action
        # We create an intermediate page right here 
        form = BroadcastForm(initial={'_selected_action': queryset.values_list('id', flat=True)})

        # We need to create a template of intermediate page with form - but this is really easy
        return render(request, "admin/broadcast_message.html", {'items': queryset, 'form': form})

what should the form look like? E.g. what should be the type of items field?

They could be just regular Django objects which were declared in models.py file.