feat(scopes): denormalize full_name and use it for sorting

The full_name attribute on the Scopes was dynamically generated on access.
This is rather inefficient, as it may cause a bunch of DB hits, especially
in deep hierarchies.

Additionally, most of the time we want scopes to be sorted in a
meaningful manner (namely, by hierarchical name). MPTTModel supports
this, but as the ordering may differ between languages, we cannot use
that functionality. This is a secondary use of the denormalized full_name.

This also required a fix in the case insensitive ordering code, as
localized fields were not treated correctly yet (casting directly to
text instead of extracting the correct language and using that to sort)

emeis/core/filters.py

@@ -1,8 +1,12 @@
 from django.conf import settings
+from django.contrib.postgres.fields.hstore import KeyTransform
+from django.core.exceptions import FieldDoesNotExist
 from django.db.models import TextField
 from django.db.models.functions import Cast, Lower
+from django.utils import translation
 from django_filters import FilterSet
 from django_filters.filters import CharFilter
+from localized_fields.fields import LocalizedField
 from rest_framework import filters
 
 from emeis.core.models import ACL, Scope, User
@@ -94,8 +98,18 @@ def _make_ordering_field(self, field, view):
         desc = field.startswith("-")
         field_name = field[1:] if desc else field
 
+        field_col = field_name
+        try:
+            model_field = view.queryset.model._meta.get_field(field_name)
+            if isinstance(model_field, LocalizedField):
+                field_col = KeyTransform(translation.get_language(), field_name)
+        except FieldDoesNotExist:
+            # This happens with metainfo__foobar style lookups,
+            # which we don't need to worry about here
+            pass
+
         if field_name in self._get_case_insensitive_fields(view):
-            field_expr = Lower(Cast(field_name, output_field=TextField()))
+            field_expr = Lower(Cast(field_col, output_field=TextField()))
             return field_expr.desc() if desc else field_expr
         return field
 

emeis/core/migrations/0010_scope_full_name.py

@@ -0,0 +1,32 @@
+# Generated by Django 3.2.15 on 2022-09-23 09:13
+
+from django.db import migrations
+import localized_fields.fields.char_field
+
+from emeis.core import models
+
+
+def set_full_name(apps, schema_editor):
+    scope_model = apps.get_model("emeis_core.scope")
+    for scope in scope_model.objects.all().iterator():
+        # explicitly trigger the set_full_name signal handler
+        models.set_full_name(instance=scope, sender=set_full_name)
+        scope.save()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("emeis_core", "0009_alter_scope_parent"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="scope",
+            name="full_name",
+            field=localized_fields.fields.char_field.LocalizedCharField(
+                blank=True, null=True, required=[], verbose_name="scope name"
+            ),
+        ),
+        migrations.RunPython(set_full_name, migrations.RunPython.noop),
+    ]

emeis/core/models.py

@@ -5,6 +5,8 @@
 from django.contrib.auth.models import AbstractBaseUser, UserManager
 from django.contrib.auth.validators import UnicodeUsernameValidator
 from django.db import models
+from django.db.models.signals import pre_save
+from django.dispatch import receiver
 from django.utils import timezone
 from django.utils.translation import gettext_lazy as _
 from localized_fields.fields import LocalizedCharField, LocalizedTextField
@@ -158,6 +160,11 @@ def is_authenticated(self):
 
 class Scope(MPTTModel, UUIDModel):
     name = LocalizedCharField(_("scope name"), blank=False, null=False, required=False)
+
+    full_name = LocalizedCharField(
+        _("scope name"), blank=True, null=True, required=False
+    )
+
     description = LocalizedTextField(
         _("scope description"), null=True, blank=True, required=False
     )
@@ -170,19 +177,25 @@ class Scope(MPTTModel, UUIDModel):
     )
     is_active = models.BooleanField(default=True)
 
-    def full_name(self, sep="\u00bb", language=None):
-        """Return full name of the scope, including parent scopes."""
-        own_name = str(self.name) if language is None else self.name[language]
+    def __str__(self):
+        return f"{type(self).__name__} ({self.full_name}, pk={self.pk})"
 
-        if self.parent:
-            parent_name = self.parent.full_name(sep, language)
-            return f"{parent_name} {sep} {own_name}"
 
-        return own_name
+@receiver(pre_save, sender=Scope)
+def set_full_name(instance, sender, **kwargs):
+    sep = "\u00bb"
 
-    def __str__(self):
-        name = self.full_name()
-        return f"{type(self).__name__} ({name}, pk={self.pk})"
+    languages = [lang for lang, _ in settings.LANGUAGES]
+
+    instance.full_name = {lang: instance.name[lang] for lang in languages}
+
+    parent = instance.parent
+    while parent:
+        instance.full_name = {
+            lang: f"{parent.name[lang]} {sep} {instance.full_name[lang]}"
+            for lang in languages
+        }
+        parent = parent.parent
 
 
 class Role(SlugModel):

emeis/core/serializers.py

@@ -1,4 +1,3 @@
-from django.conf import settings
 from django.contrib.auth.models import AnonymousUser
 from generic_permissions.validation import ValidatorMixin
 from rest_framework_json_api import serializers
@@ -74,14 +73,6 @@ class Meta:
 
 
 class ScopeSerializer(BaseSerializer):
-    full_name = serializers.SerializerMethodField()
-
-    def get_full_name(self, instance):
-        return {
-            language: instance.full_name(language=language)
-            for language, _ in settings.LANGUAGES
-        }
-
     class Meta:
         model = Scope
         fields = BaseSerializer.Meta.fields + (
@@ -92,6 +83,7 @@ class Meta:
             "full_name",
             "is_active",
         )
+        read_only_fields = ["full_name"]
 
 
 class PermissionSerializer(BaseSerializer):