API: Release Pagination

this also fixes the index on releases (since they are always ordered
in the context of a particular project, this should be part of the
index)

See #146

releases/api_views.py

@@ -1,11 +1,21 @@
 from rest_framework import viewsets
 from rest_framework.exceptions import ValidationError
 
-from projects.models import Project
-from .models import Release, ordered_releases
+from bugsink.api_pagination import AscDescCursorPagination
+
+from .models import Release
 from .serializers import ReleaseListSerializer, ReleaseDetailSerializer, ReleaseCreateSerializer
 
 
+class ReleasePagination(AscDescCursorPagination):
+    # Cursor pagination requires an indexed, mostly-stable ordering field. We use `digest_order`: We require
+    # ?project=<id> and have a composite (project_id, date_released) index, so ORDER BY date_released after filtering by
+    # project is fast and cursor-stable. (also note that date_released generally comes in in-order).
+    base_ordering = ("date_released",)
+    page_size = 250
+    default_direction = "desc"
+
+
 class ReleaseViewSet(viewsets.ModelViewSet):
     """
     LIST requires: ?project=<id>
@@ -15,6 +25,7 @@ class ReleaseViewSet(viewsets.ModelViewSet):
     queryset = Release.objects.all()
     serializer_class = ReleaseListSerializer
     http_method_names = ["get", "post", "head", "options"]
+    pagination_class = ReleasePagination
 
     def filter_queryset(self, queryset):
         queryset = super().filter_queryset(queryset)
@@ -26,10 +37,7 @@ class ReleaseViewSet(viewsets.ModelViewSet):
         if not project_id:
             raise ValidationError({"project": ["This field is required."]})
 
-        # application-ordering (as opposed to in-db); will have performance implications, but we do "correct first, fast
-        # later":
-        project = Project.objects.get(pk=project_id)
-        return ordered_releases(project=project)
+        return queryset.filter(project=project_id)
 
     def get_serializer_class(self):
         if self.action == "create":

releases/migrations/0004_fix_indexes.py

@@ -0,0 +1,29 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("projects", "0014_alter_projectmembership_project"),
+        ("releases", "0003_alter_release_project"),
+    ]
+
+    operations = [
+        migrations.RemoveIndex(
+            model_name="release",
+            name="releases_re_sort_ep_5c07c8_idx",
+        ),
+        migrations.AddIndex(
+            model_name="release",
+            index=models.Index(
+                fields=["project", "sort_epoch"], name="releases_re_project_1ceb8b_idx"
+            ),
+        ),
+        migrations.AddIndex(
+            model_name="release",
+            index=models.Index(
+                fields=["project", "date_released"],
+                name="releases_re_project_b17273_idx",
+            ),
+        ),
+    ]

releases/models.py

@@ -83,7 +83,8 @@ class Release(models.Model):
         unique_together = ("project", "version")
 
         indexes = [
-            models.Index(fields=["sort_epoch"]),
+            models.Index(fields=["project", "sort_epoch"]),
+            models.Index(fields=["project", "date_released"]),
         ]
 
     def get_short_version(self):

releases/test_api.py

@@ -1,10 +1,12 @@
 from django.test import TestCase as DjangoTestCase
 from django.urls import reverse
+from django.utils import timezone
 from rest_framework.test import APIClient
 
 from bsmain.models import AuthToken
 from projects.models import Project
-from releases.models import ordered_releases
+from releases.models import Release
+from releases.api_views import ReleaseViewSet
 
 
 class ReleaseApiTests(DjangoTestCase):
@@ -25,19 +27,6 @@ class ReleaseApiTests(DjangoTestCase):
         self.assertEqual(response.status_code, 400)
         self.assertEqual({"project": ["This field is required."]}, response.json())
 
-    def test_list_uses_ordered_releases(self):
-        # Create in arbitrary order
-        self._create("1.0.0")
-        self._create("1.0.0+build")
-        self._create("1.0.1")
-
-        response = self.client.get(reverse("api:release-list"), {"project": str(self.project.id)})
-        self.assertEqual(response.status_code, 200)
-
-        versions_from_api = [row["version"] for row in response.json()["results"]]
-        versions_expected = [r.version for r in ordered_releases(project=self.project)]
-        self.assertEqual(versions_from_api, versions_expected)
-
     def test_create_new_returns_201_and_detail_shape(self):
         response = self._create("1.2.3", timestamp="2024-01-01T00:00:00Z")
         self.assertEqual(response.status_code, 201)
@@ -90,3 +79,58 @@ class ReleaseApiTests(DjangoTestCase):
         self.assertEqual(put_response.status_code, 405)
         self.assertEqual(patch_response.status_code, 405)
         self.assertEqual(delete_response.status_code, 405)
+
+
+class ReleasePaginationTests(DjangoTestCase):
+    def setUp(self):
+        self.client = APIClient()
+        token = AuthToken.objects.create()
+        self.client.credentials(HTTP_AUTHORIZATION=f"Bearer {token.token}")
+        self.old_size = ReleaseViewSet.pagination_class.page_size
+        ReleaseViewSet.pagination_class.page_size = 2
+
+    def tearDown(self):
+        ReleaseViewSet.pagination_class.page_size = self.old_size
+
+    def _make_releases(self, project, deltas):
+        base = timezone.now().replace(microsecond=0)
+        releases = []
+        for i, delta in enumerate(deltas):
+            rel = Release.objects.create(
+                project=project,
+                version=f"v{i}",
+                date_released=base + delta,
+            )
+            releases.append(rel)
+        return releases
+
+    def _ids(self, resp):
+        return [row["id"] for row in resp.json()["results"]]
+
+    def test_date_released_desc_two_pages(self):
+        proj = Project.objects.create(name="P")
+        releases = self._make_releases(
+            proj, [timezone.timedelta(days=i) for i in range(5)]
+        )
+
+        r1 = self.client.get(
+            reverse("api:release-list"), {"project": str(proj.id), "order": "desc"}
+        )
+        self.assertEqual(self._ids(r1), [str(releases[4].id), str(releases[3].id)])
+
+        r2 = self.client.get(r1.json()["next"])
+        self.assertEqual(self._ids(r2), [str(releases[2].id), str(releases[1].id)])
+
+    def test_date_released_asc_two_pages(self):
+        proj = Project.objects.create(name="P2")
+        releases = self._make_releases(
+            proj, [timezone.timedelta(days=i) for i in range(5)]
+        )
+
+        r1 = self.client.get(
+            reverse("api:release-list"), {"project": str(proj.id), "order": "asc"}
+        )
+        self.assertEqual(self._ids(r1), [str(releases[0].id), str(releases[1].id)])
+
+        r2 = self.client.get(r1.json()["next"])
+        self.assertEqual(self._ids(r2), [str(releases[2].id), str(releases[3].id)])