From 187e13c5259d347cd6f34522246a191b3a4a0c47 Mon Sep 17 00:00:00 2001
From: Jacob Nesbitt <jjnesbitt2@gmail.com>
Date: Wed, 6 Mar 2024 12:07:22 -0500
Subject: [PATCH] Change collation on asset path field

---
 .../migrations/0006_asset_path_collation.py   | 24 +++++++++++++++++++
 dandiapi/api/models/asset.py                  |  2 +-
 dandiapi/api/tests/test_asset.py              | 19 +++++++++++++++
 3 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 dandiapi/api/migrations/0006_asset_path_collation.py

diff --git a/dandiapi/api/migrations/0006_asset_path_collation.py b/dandiapi/api/migrations/0006_asset_path_collation.py
new file mode 100644
index 000000000..300e0b6e8
--- /dev/null
+++ b/dandiapi/api/migrations/0006_asset_path_collation.py
@@ -0,0 +1,24 @@
+# Generated by Django 4.1.13 on 2024-03-06 17:04
+from __future__ import annotations
+
+from django.db import migrations, models
+
+import dandiapi.api.models.asset
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('api', '0005_null_charfield'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='asset',
+            name='path',
+            field=models.CharField(
+                db_collation='C.utf8',
+                max_length=512,
+                validators=[dandiapi.api.models.asset.validate_asset_path],
+            ),
+        ),
+    ]
diff --git a/dandiapi/api/models/asset.py b/dandiapi/api/models/asset.py
index b967d9b5c..5330562b6 100644
--- a/dandiapi/api/models/asset.py
+++ b/dandiapi/api/models/asset.py
@@ -134,7 +134,7 @@ class Status(models.TextChoices):
         INVALID = 'Invalid'
 
     asset_id = models.UUIDField(unique=True, default=uuid.uuid4)
-    path = models.CharField(max_length=512, validators=[validate_asset_path])
+    path = models.CharField(max_length=512, validators=[validate_asset_path], db_collation='C.utf8')
     blob = models.ForeignKey(
         AssetBlob, related_name='assets', on_delete=models.CASCADE, null=True, blank=True
     )
diff --git a/dandiapi/api/tests/test_asset.py b/dandiapi/api/tests/test_asset.py
index 715c5fc82..14588dec9 100644
--- a/dandiapi/api/tests/test_asset.py
+++ b/dandiapi/api/tests/test_asset.py
@@ -369,6 +369,25 @@ def test_asset_rest_list_ordering(api_client, version, asset_factory, order_para
     assert result_paths == ordering
 
 
+@pytest.mark.django_db()
+def test_asset_path_ordering(api_client, version, asset_factory):
+    # The default collation will ignore special characters, including slashes, on the first pass. If
+    # there are ties, it uses these characters to break ties. This means that in the below example,
+    # removing the slashes leads to a comparison of 'az' and 'aaz', which would obviously sort the
+    # latter before the former. However, with the slashes, it's clear that 'a/z' should come before
+    # 'aa/z'. This is fixed by changing the collation of the path field, and as such this test
+    # serves as a regression test.
+    a = asset_factory(path='a/z')
+    b = asset_factory(path='aa/z')
+    version.assets.add(a)
+    version.assets.add(b)
+
+    asset_listing = Asset.objects.filter(versions__in=[version]).order_by('path')
+    assert asset_listing.count() == 2
+    assert asset_listing[0].pk == a.pk
+    assert asset_listing[1].pk == b.pk
+
+
 @pytest.mark.django_db()
 def test_asset_rest_retrieve(api_client, version, asset, asset_factory):
     version.assets.add(asset)