Collating snippets into derivable class

Author: rhaver

simple_history/admin.py

@@ -3,7 +3,7 @@
 from django.conf import settings
 from django.contrib import admin
 from django.contrib.admin import helpers
-from django.contrib.admin.utils import unquote
+from django.contrib.admin.utils import quote, unquote
 from django.contrib.auth import get_permission_codename
 from django.core.exceptions import PermissionDenied
 from django.shortcuts import get_object_or_404, render
@@ -286,35 +286,38 @@ def enforce_history_permissions(self):
         )
 
 
-class SimpleHistoryShowDeletedFilter(admin.SimpleListFilter):
-    title = "Entries"
-    parameter_name = "entries"
+class SimpleHistoryWithDeletedAdmin(SimpleHistoryAdmin):
+    class SimpleHistoryShowDeletedFilter(admin.SimpleListFilter):
+        title = "Entries"
+        parameter_name = "entries"
 
-    def lookups(self, request, model_admin):
-        return (("deleted_only", "Only Deleted"),)
+        def lookups(self, request, model_admin):
+                return (("deleted_only", "Only Deleted"),)
 
-    def queryset(self, request, queryset):
-        if self.value():
-            return queryset.model.history.filter(history_type="-").distinct()
-        return queryset
+        def queryset(self, request, queryset):
+            if self.value():
+                return queryset.model.history.filter(history_type="-").distinct()
+            return queryset
 
-
-class YourModelAdmin(SimpleHistoryAdmin):
     def get_changelist(self, request, **kwargs):
         def url_from_result_maker(history=False):
             def custom_url_for_result(self, result):
                 pk = getattr(result, self.pk_attname)
-                from django.urls import reverse
-                from django.contrib.admin.utils import quote
                 route_type = 'history' if history else 'change'
                 route = f'{self.opts.app_label}_{self.opts.model_name}_{route_type}'
                 return reverse(f'admin:{route}',
                                args=(quote(pk),),
                                current_app=self.model_admin.admin_site.name)
             return custom_url_for_result
+
         changelist = super().get_changelist(request, **kwargs)
         if request.GET.get('entries', None) == 'deleted_only':
             changelist.url_for_result = url_from_result_maker(history=True)
         else:
             changelist.url_for_result = url_from_result_maker(history=False)
         return changelist
+
+    def get_list_filter(self, request):
+        return [self.SimpleHistoryShowDeletedFilter] + [
+            f for f in super().get_list_filter(request)
+        ]