channel-folders: Update unique name constraint.

This commit updates code to require unique names for only
non-archived folders in a realm, which means a folder can
use a name which is being used by an archived folder.

zerver/lib/channel_folders.py

@@ -32,7 +32,7 @@ def check_channel_folder_name(name: str, realm: Realm) -> None:
             )
         )
 
-    if ChannelFolder.objects.filter(name__iexact=name, realm=realm).exists():
+    if ChannelFolder.objects.filter(name__iexact=name, realm=realm, is_archived=False).exists():
         raise JsonableError(_("Channel folder name already in use"))
 
 

zerver/migrations/0746_alter_channelfolder_unique_together_and_more.py

@@ -0,0 +1,26 @@
+# Generated by Django 5.2.4 on 2025-07-29 09:55
+
+import django.db.models.functions.text
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("zerver", "0745_usersetting_web_left_sidebar_show_channel_folders"),
+    ]
+
+    operations = [
+        migrations.AlterUniqueTogether(
+            name="channelfolder",
+            unique_together=set(),
+        ),
+        migrations.AddConstraint(
+            model_name="channelfolder",
+            constraint=models.UniqueConstraint(
+                django.db.models.functions.text.Lower("name"),
+                models.F("realm"),
+                condition=models.Q(("is_archived", False)),
+                name="unique_realm_folder_name_when_not_archived",
+            ),
+        ),
+    ]

zerver/models/channel_folders.py

@@ -1,4 +1,6 @@
 from django.db import models
+from django.db.models import Q
+from django.db.models.functions import Lower
 from django.utils.timezone import now as timezone_now
 
 from zerver.models.realms import Realm
@@ -19,4 +21,11 @@ class ChannelFolder(models.Model):
     is_archived = models.BooleanField(default=False)
 
     class Meta:
-        unique_together = ("realm", "name")
+        constraints = [
+            models.UniqueConstraint(
+                Lower("name"),
+                "realm",
+                condition=Q(is_archived=False),
+                name="unique_realm_folder_name_when_not_archived",
+            ),
+        ]

zerver/tests/test_channel_folders.py

@@ -2,7 +2,7 @@ from typing import Any
 
 import orjson
 
-from zerver.actions.channel_folders import check_add_channel_folder
+from zerver.actions.channel_folders import check_add_channel_folder, do_archive_channel_folder
 from zerver.actions.streams import do_change_stream_folder, do_deactivate_stream
 from zerver.lib.test_classes import ZulipTestCase
 from zerver.models import ChannelFolder
@@ -41,6 +41,14 @@ class ChannelFolderCreationTest(ZulipTestCase):
         result = self.client_post("/json/channel_folders/create", params)
         self.assert_json_error(result, "Channel folder name already in use")
 
+        # Archived folder names can be reused.
+        folder = ChannelFolder.objects.get(name="Frontend", realm=realm)
+        do_archive_channel_folder(folder, acting_user=self.example_user("iago"))
+
+        result = self.client_post("/json/channel_folders/create", params)
+        self.assert_json_success(result)
+        self.assertTrue(ChannelFolder.objects.filter(realm=realm, name="Frontend").exists())
+
         # Folder names should be unique case-insensitively.
         params["name"] = "frontEND"
         result = self.client_post("/json/channel_folders/create", params)