Such a mess

src/documents/consumer.py

@@ -775,7 +775,7 @@ class ConsumerPlugin(
 
         if self.metadata.tag_ids:
             for tag_id in self.metadata.tag_ids:
-                document.tags.add(Tag.objects.get(pk=tag_id))
+                document.add_nested_tags(Tag.objects.get(pk=tag_id))
 
         if self.metadata.storage_path_id:
             document.storage_path = StoragePath.objects.get(

src/documents/migrations/1063_tag_parent.py

@@ -0,0 +1,26 @@
+# Generated by Django 5.1.5 on 2025-02-10 06:02
+
+import django.db.models.deletion
+from django.db import migrations
+from django.db import models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("documents", "1062_alter_savedviewfilterrule_rule_type"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="tag",
+            name="parent",
+            field=models.ForeignKey(
+                blank=True,
+                null=True,
+                on_delete=django.db.models.deletion.CASCADE,
+                related_name="children",
+                to="documents.tag",
+                verbose_name="parent",
+            ),
+        ),
+    ]

src/documents/models.py

@@ -12,6 +12,7 @@ from celery import states
 from django.conf import settings
 from django.contrib.auth.models import Group
 from django.contrib.auth.models import User
+from django.core.exceptions import ValidationError
 from django.core.validators import MaxValueValidator
 from django.core.validators import MinValueValidator
 from django.db import models
@@ -113,10 +114,38 @@ class Tag(MatchingModel):
         ),
     )
 
+    parent = models.ForeignKey(
+        "self",
+        blank=True,
+        null=True,
+        on_delete=models.CASCADE,
+        related_name="children",
+        verbose_name=_("parent"),
+    )
+
     class Meta(MatchingModel.Meta):
         verbose_name = _("tag")
         verbose_name_plural = _("tags")
 
+    def get_all_descendants(self):
+        descendants = []
+        for child in self.children.all():
+            descendants.append(child)
+            descendants.extend(child.get_all_descendants())
+        return descendants
+
+    def get_all_ancestors(self):
+        ancestors = []
+        if self.parent:
+            ancestors.append(self.parent)
+            ancestors.extend(self.parent.get_all_ancestors())
+        return ancestors
+
+    def clean(self):
+        if self.parent == self:
+            raise ValidationError("Cannot set itself as parent.")
+        return super().clean()
+
 
 class DocumentType(MatchingModel):
     class Meta(MatchingModel.Meta):
@@ -378,6 +407,12 @@ class Document(SoftDeleteModel, ModelWithOwner):
     def created_date(self):
         return timezone.localdate(self.created)
 
+    def add_nested_tags(self, tags):
+        for tag in tags:
+            self.tags.add(tag)
+            if tag.parent:
+                self.add_nested_tags([tag.parent])
+
 
 class Log(models.Model):
     LEVELS = (

src/documents/serialisers.py

@@ -528,6 +528,11 @@ class TagSerializer(MatchingModelSerializer, OwnedObjectSerializer):
 
     text_color = serializers.SerializerMethodField()
 
+    children = SerializerMethodField()
+
+    def get_children(self, obj):
+        return TagSerializer(obj.children.all(), many=True).data
+
     class Meta:
         model = Tag
         fields = (
@@ -545,6 +550,8 @@ class TagSerializer(MatchingModelSerializer, OwnedObjectSerializer):
             "permissions",
             "user_can_change",
             "set_permissions",
+            "parent",
+            "children",
         )
 
     def validate_color(self, color):
@@ -952,6 +959,23 @@ class DocumentSerializer(
                             custom_field_instance.field,
                             doc_id,
                         )
+        if "tags" in validated_data:
+            # add all parent tags
+            all_ancestor_tags = set(validated_data["tags"])
+            for tag in validated_data["tags"]:
+                all_ancestor_tags.update(tag.get_all_ancestors())
+            validated_data["tags"] = list(all_ancestor_tags)
+            # remove any children for parents that are being removed
+            tag_parents_being_removed = [
+                tag
+                for tag in instance.tags.all()
+                if tag not in validated_data["tags"] and tag.children.count() > 0
+            ]
+            validated_data["tags"] = [
+                tag
+                for tag in validated_data["tags"]
+                if tag not in tag_parents_being_removed
+            ]
         if validated_data.get("remove_inbox_tags"):
             tag_ids_being_added = (
                 [

src/documents/signals/handlers.py

@@ -248,7 +248,7 @@ def set_tags(
             extra={"group": logging_group},
         )
 
-        document.tags.add(*relevant_tags)
+        document.add_nested_tags(relevant_tags)
 
 
 def set_storage_path(