Merge branch '293-add-helper-function-to-filter-a-queryset-by-a-rule' into 'master'

Resolve "Add helper function to filter a queryset by a rule"

Closes #293

See merge request AlekSIS/official/AlekSIS!318

aleksis/core/util/core_helpers.py

@@ -9,7 +9,7 @@ from typing import Any, Callable, Optional, Sequence, Union
 from uuid import uuid4
 
 from django.conf import settings
-from django.db.models import Model
+from django.db.models import Model, QuerySet
 from django.http import HttpRequest
 from django.shortcuts import get_object_or_404
 from django.utils import timezone
@@ -17,6 +17,8 @@ from django.utils.functional import lazy
 
 from django_global_request.middleware import get_request
 
+from cache_memoize import cache_memoize
+
 from aleksis.core.util import messages
 
 
@@ -357,3 +359,20 @@ def handle_uploaded_file(f, filename: str):
     with open(filename, "wb+") as destination:
         for chunk in f.chunks():
             destination.write(chunk)
+
+
+@cache_memoize(3600)
+def queryset_rules_filter(
+    obj: Union[HttpRequest, Model], queryset: QuerySet, perm: str
+) -> QuerySet:
+    """Filter queryset by user and permission."""
+
+    wanted_objects = set()
+    if isinstance(obj, HttpRequest) and hasattr(obj, "user"):
+        obj = obj.user
+
+    for item in queryset:
+        if obj.has_perm(perm, item):
+            wanted_objects.add(item.pk)
+
+    return queryset.filter(pk__in=wanted_objects)

aleksis/core/util/predicates.py

 from django.contrib.auth.backends import ModelBackend
 from django.contrib.auth.models import User
+from django.contrib.contenttypes.models import ContentType
 from django.db.models import Model
 from django.http import HttpRequest
 
@@ -8,7 +9,7 @@ from guardian.shortcuts import get_objects_for_user
 from rules import predicate
 
 from ..models import Group
-from .core_helpers import get_site_preferences
+from .core_helpers import get_site_preferences, queryset_rules_filter
 from .core_helpers import has_person as has_person_helper
 
 
@@ -57,15 +58,17 @@ def has_any_object(perm: str, klass):
     """Check if has any object.
 
     Build predicate which checks whether a user has access
-    to objects with the provided permission.
+    to objects with the provided permission or rule.
     """
     name = f"has_any_object:{perm}"
 
     @predicate(name)
     def fn(user: User) -> bool:
-        objs = get_objects_for_user(user, perm, klass)
-        return len(objs) > 0
-
+        ct_perm = ContentType.objects.get(app_label=perm.split('.', 1)[0], permission__codename=perm.split('.', 1)[1])
+        if ct_perm and ct_perm.model_class() == klass:
+            return get_objects_for_user(user, perm, klass).exists()
+        else:
+            return queryset_rules_filter(user, klass.objects.all(), perm).exists()
     return fn