Add allowed_campaign_count field to Channel model and implement counter cache logic

twitch/apps.py

@@ -39,6 +39,7 @@ class TwitchConfig(AppConfig):
 
         # Register post_save signal handlers that dispatch image download tasks
         # when new Twitch records are created.
+        from django.db.models.signals import m2m_changed  # noqa: I001, PLC0415
         from django.db.models.signals import post_save  # noqa: PLC0415
 
         from twitch.models import DropBenefit  # noqa: PLC0415
@@ -46,6 +47,7 @@ class TwitchConfig(AppConfig):
         from twitch.models import Game  # noqa: PLC0415
         from twitch.models import RewardCampaign  # noqa: PLC0415
         from twitch.signals import on_drop_benefit_saved  # noqa: PLC0415
+        from twitch.signals import on_drop_campaign_allow_channels_changed  # noqa: PLC0415
         from twitch.signals import on_drop_campaign_saved  # noqa: PLC0415
         from twitch.signals import on_game_saved  # noqa: PLC0415
         from twitch.signals import on_reward_campaign_saved  # noqa: PLC0415
@@ -54,3 +56,8 @@ class TwitchConfig(AppConfig):
         post_save.connect(on_drop_campaign_saved, sender=DropCampaign)
         post_save.connect(on_drop_benefit_saved, sender=DropBenefit)
         post_save.connect(on_reward_campaign_saved, sender=RewardCampaign)
+        m2m_changed.connect(
+            on_drop_campaign_allow_channels_changed,
+            sender=DropCampaign.allow_channels.through,
+            dispatch_uid="twitch_drop_campaign_allow_channels_counter_cache",
+        )

twitch/migrations/0021_channel_allowed_campaign_count_cache.py

@@ -0,0 +1,83 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from django.db import migrations
+from django.db import models
+
+if TYPE_CHECKING:
+    from django.db.backends.base.schema import BaseDatabaseSchemaEditor
+    from django.db.migrations.state import StateApps
+
+    from twitch.models import Channel
+    from twitch.models import DropCampaign
+
+
+def backfill_allowed_campaign_count(
+    apps: StateApps,
+    schema_editor: BaseDatabaseSchemaEditor,
+) -> None:
+    """Populate Channel.allowed_campaign_count from the M2M through table."""
+    del schema_editor
+
+    Channel: type[Channel] = apps.get_model("twitch", "Channel")
+    DropCampaign: type[DropCampaign] = apps.get_model("twitch", "DropCampaign")
+    through_model: type[Channel] = DropCampaign.allow_channels.through
+
+    counts_by_channel = {
+        row["channel_id"]: row["campaign_count"]
+        for row in (
+            through_model.objects.values("channel_id").annotate(
+                campaign_count=models.Count("dropcampaign_id"),
+            )
+        )
+    }
+
+    channels: list[Channel] = list(
+        Channel.objects.all().only("id", "allowed_campaign_count"),
+    )
+    for channel in channels:
+        channel.allowed_campaign_count = counts_by_channel.get(channel.pk, 0)
+
+    if channels:
+        Channel.objects.bulk_update(
+            channels,
+            ["allowed_campaign_count"],
+            batch_size=1000,
+        )
+
+
+def noop_reverse(
+    apps: StateApps,
+    schema_editor: BaseDatabaseSchemaEditor,
+) -> None:
+    """No-op reverse migration for cached counters."""
+    del apps
+    del schema_editor
+
+
+class Migration(migrations.Migration):
+    """Add cached channel campaign counts and backfill existing rows."""
+
+    dependencies = [
+        ("twitch", "0020_rewardcampaign_tw_reward_ends_starts_idx"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="channel",
+            name="allowed_campaign_count",
+            field=models.PositiveIntegerField(
+                default=0,
+                help_text="Cached number of drop campaigns that allow this channel.",
+            ),
+        ),
+        migrations.AddIndex(
+            model_name="channel",
+            index=models.Index(
+                fields=["-allowed_campaign_count", "name"],
+                name="tw_chan_cc_name_idx",
+            ),
+        ),
+        migrations.RunPython(backfill_allowed_campaign_count, noop_reverse),
+    ]

twitch/models.py

@@ -2,12 +2,15 @@ import logging
 from collections import OrderedDict
 from typing import TYPE_CHECKING
 from typing import Any
+from typing import Self
 
 import auto_prefetch
 from django.conf import settings
 from django.contrib.postgres.indexes import GinIndex
 from django.db import models
+from django.db.models import F
 from django.db.models import Prefetch
+from django.db.models import Q
 from django.urls import reverse
 from django.utils import timezone
 from django.utils.html import format_html
@@ -347,6 +350,11 @@ class Channel(auto_prefetch.Model):
         auto_now=True,
     )
 
+    allowed_campaign_count = models.PositiveIntegerField(
+        help_text="Cached number of drop campaigns that allow this channel.",
+        default=0,
+    )
+
     class Meta(auto_prefetch.Model.Meta):
         ordering = ["display_name"]
         indexes = [
@@ -355,12 +363,47 @@ class Channel(auto_prefetch.Model):
             models.Index(fields=["twitch_id"]),
             models.Index(fields=["added_at"]),
             models.Index(fields=["updated_at"]),
+            models.Index(
+                fields=["-allowed_campaign_count", "name"],
+                name="tw_chan_cc_name_idx",
+            ),
         ]
 
     def __str__(self) -> str:
         """Return a string representation of the channel."""
         return self.display_name or self.name or self.twitch_id
 
+    @classmethod
+    def for_list_view(
+        cls,
+        search_query: str | None = None,
+    ) -> models.QuerySet[Channel]:
+        """Return channels for list view with campaign counts.
+
+        Args:
+            search_query: Optional free-text search for username/display name.
+
+        Returns:
+            QuerySet optimized for channel list rendering.
+        """
+        queryset: models.QuerySet[Self, Self] = cls.objects.only(
+            "twitch_id",
+            "name",
+            "display_name",
+            "allowed_campaign_count",
+        )
+
+        normalized_query: str = (search_query or "").strip()
+        if normalized_query:
+            queryset = queryset.filter(
+                Q(name__icontains=normalized_query)
+                | Q(display_name__icontains=normalized_query),
+            )
+
+        return queryset.annotate(
+            campaign_count=F("allowed_campaign_count"),
+        ).order_by("-campaign_count", "name")
+
 
 # MARK: DropCampaign
 class DropCampaign(auto_prefetch.Model):

twitch/signals.py

@@ -3,6 +3,8 @@ from __future__ import annotations
 import logging
 from typing import Any
 
+from django.db.models import Count
+
 logger = logging.getLogger("ttvdrops.signals")
 
 
@@ -63,3 +65,65 @@ def on_reward_campaign_saved(
         from twitch.tasks import download_reward_campaign_image  # noqa: PLC0415
 
         _dispatch(download_reward_campaign_image, instance.pk)
+
+
+def _refresh_allowed_campaign_counts(channel_ids: set[int]) -> None:
+    """Recompute and persist cached campaign counters for the given channels."""
+    if not channel_ids:
+        return
+
+    from twitch.models import Channel  # noqa: PLC0415
+    from twitch.models import DropCampaign  # noqa: PLC0415
+
+    through_model: type[Channel] = DropCampaign.allow_channels.through
+    counts_by_channel: dict[int, int] = {
+        row["channel_id"]: row["campaign_count"]
+        for row in (
+            through_model.objects
+            .filter(channel_id__in=channel_ids)
+            .values("channel_id")
+            .annotate(campaign_count=Count("dropcampaign_id"))
+        )
+    }
+
+    channels = list(
+        Channel.objects.filter(pk__in=channel_ids).only("pk", "allowed_campaign_count"),
+    )
+    for channel in channels:
+        channel.allowed_campaign_count = counts_by_channel.get(channel.pk, 0)
+
+    if channels:
+        Channel.objects.bulk_update(channels, ["allowed_campaign_count"])
+
+
+def on_drop_campaign_allow_channels_changed(  # noqa: PLR0913, PLR0917
+    sender: Any,  # noqa: ANN401
+    instance: Any,  # noqa: ANN401
+    action: str,
+    reverse: bool,  # noqa: FBT001
+    model: Any,  # noqa: ANN401
+    pk_set: set[int] | None,
+    **kwargs: Any,  # noqa: ANN401
+) -> None:
+    """Keep Channel.allowed_campaign_count in sync for allow_channels M2M changes."""
+    if action == "pre_clear" and not reverse:
+        # post_clear does not expose removed channel IDs; snapshot before clearing.
+        instance._pre_clear_channel_ids = set(  # pyright: ignore[reportAttributeAccessIssue]  # noqa: SLF001
+            instance.allow_channels.values_list("pk", flat=True),  # pyright: ignore[reportAttributeAccessIssue]
+        )
+        return
+
+    if action not in {"post_add", "post_remove", "post_clear"}:
+        return
+
+    channel_ids: set[int] = set()
+    if reverse:
+        channel_pk: int | None = getattr(instance, "pk", None)
+        if isinstance(channel_pk, int):
+            channel_ids.add(channel_pk)
+    elif action == "post_clear":
+        channel_ids = set(getattr(instance, "_pre_clear_channel_ids", set()))
+    else:
+        channel_ids = set(pk_set or set())
+
+    _refresh_allowed_campaign_counts(channel_ids)

twitch/tests/test_migrations.py

@@ -0,0 +1,86 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+import pytest
+from django.db import connection
+from django.db.migrations.executor import MigrationExecutor
+from django.db.migrations.state import StateApps
+
+if TYPE_CHECKING:
+    from django.db.migrations.state import StateApps
+
+    from twitch.models import Channel
+    from twitch.models import DropCampaign
+    from twitch.models import Game
+
+
+@pytest.mark.django_db(transaction=True)
+def test_0021_backfills_allowed_campaign_count() -> None:  # noqa: PLR0914
+    """Migration 0021 should backfill cached allowed campaign counts."""
+    migrate_from: list[tuple[str, str]] = [
+        ("twitch", "0020_rewardcampaign_tw_reward_ends_starts_idx"),
+    ]
+    migrate_to: list[tuple[str, str]] = [
+        ("twitch", "0021_channel_allowed_campaign_count_cache"),
+    ]
+
+    executor = MigrationExecutor(connection)
+    executor.migrate(migrate_from)
+    old_apps: StateApps = executor.loader.project_state(migrate_from).apps
+
+    Game: type[Game] = old_apps.get_model("twitch", "Game")
+    Channel: type[Channel] = old_apps.get_model("twitch", "Channel")
+    DropCampaign: type[DropCampaign] = old_apps.get_model("twitch", "DropCampaign")
+
+    game = Game.objects.create(
+        twitch_id="migration_backfill_game",
+        name="Migration Backfill Game",
+        display_name="Migration Backfill Game",
+    )
+    channel1 = Channel.objects.create(
+        twitch_id="migration_backfill_channel_1",
+        name="migrationbackfillchannel1",
+        display_name="Migration Backfill Channel 1",
+    )
+    channel2 = Channel.objects.create(
+        twitch_id="migration_backfill_channel_2",
+        name="migrationbackfillchannel2",
+        display_name="Migration Backfill Channel 2",
+    )
+    _channel3 = Channel.objects.create(
+        twitch_id="migration_backfill_channel_3",
+        name="migrationbackfillchannel3",
+        display_name="Migration Backfill Channel 3",
+    )
+    campaign1 = DropCampaign.objects.create(
+        twitch_id="migration_backfill_campaign_1",
+        name="Migration Backfill Campaign 1",
+        game=game,
+        operation_names=["DropCampaignDetails"],
+    )
+    campaign2 = DropCampaign.objects.create(
+        twitch_id="migration_backfill_campaign_2",
+        name="Migration Backfill Campaign 2",
+        game=game,
+        operation_names=["DropCampaignDetails"],
+    )
+
+    campaign1.allow_channels.add(channel1, channel2)
+    campaign2.allow_channels.add(channel1)
+
+    executor = MigrationExecutor(connection)
+    executor.migrate(migrate_to)
+    new_apps: StateApps = executor.loader.project_state(migrate_to).apps
+    new_channel: type[Channel] = new_apps.get_model("twitch", "Channel")
+
+    counts_by_twitch_id: dict[str, int] = {
+        channel.twitch_id: channel.allowed_campaign_count
+        for channel in new_channel.objects.order_by("twitch_id")
+    }
+
+    assert counts_by_twitch_id == {
+        "migration_backfill_channel_1": 2,
+        "migration_backfill_channel_2": 1,
+        "migration_backfill_channel_3": 0,
+    }

twitch/tests/test_views.py

@@ -494,6 +494,115 @@ class TestChannelListView:
         assert len(channels) == 1
         assert channels[0].twitch_id == channel.twitch_id
 
+    def test_channel_list_queryset_only_selects_rendered_fields(self) -> None:
+        """Channel list queryset should defer non-rendered fields."""
+        channel: Channel = Channel.objects.create(
+            twitch_id="channel_minimal_fields",
+            name="channelminimalfields",
+            display_name="Channel Minimal Fields",
+        )
+
+        queryset: QuerySet[Channel] = Channel.for_list_view()
+        fetched_channel: Channel | None = queryset.filter(
+            twitch_id=channel.twitch_id,
+        ).first()
+
+        assert fetched_channel is not None
+        assert hasattr(fetched_channel, "campaign_count")
+
+        deferred_fields: set[str] = fetched_channel.get_deferred_fields()
+        assert "added_at" in deferred_fields
+        assert "updated_at" in deferred_fields
+        assert "name" not in deferred_fields
+        assert "display_name" not in deferred_fields
+        assert "twitch_id" not in deferred_fields
+
+    def test_channel_list_queryset_uses_counter_cache_without_join(self) -> None:
+        """Channel list SQL should use cached count and avoid campaign join/grouping."""
+        sql: str = str(Channel.for_list_view().query).upper()
+
+        assert "TWITCH_DROPCAMPAIGN_ALLOW_CHANNELS" not in sql
+        assert "GROUP BY" not in sql
+        assert "ALLOWED_CAMPAIGN_COUNT" in sql
+
+    def test_channel_allowed_campaign_count_updates_on_add_remove_clear(self) -> None:
+        """Counter cache should stay in sync when campaign-channel links change."""
+        game: Game = Game.objects.create(
+            twitch_id="counter_cache_game",
+            name="Counter Cache Game",
+            display_name="Counter Cache Game",
+        )
+
+        channel: Channel = Channel.objects.create(
+            twitch_id="counter_cache_channel",
+            name="countercachechannel",
+            display_name="Counter Cache Channel",
+        )
+        campaign1: DropCampaign = DropCampaign.objects.create(
+            twitch_id="counter_cache_campaign_1",
+            name="Counter Cache Campaign 1",
+            game=game,
+            operation_names=["DropCampaignDetails"],
+        )
+        campaign2: DropCampaign = DropCampaign.objects.create(
+            twitch_id="counter_cache_campaign_2",
+            name="Counter Cache Campaign 2",
+            game=game,
+            operation_names=["DropCampaignDetails"],
+        )
+
+        campaign1.allow_channels.add(channel)
+        channel.refresh_from_db()
+        assert channel.allowed_campaign_count == 1
+
+        campaign2.allow_channels.add(channel)
+        channel.refresh_from_db()
+        assert channel.allowed_campaign_count == 2
+
+        campaign1.allow_channels.remove(channel)
+        channel.refresh_from_db()
+        assert channel.allowed_campaign_count == 1
+
+        campaign2.allow_channels.clear()
+        channel.refresh_from_db()
+        assert channel.allowed_campaign_count == 0
+
+    def test_channel_allowed_campaign_count_updates_on_set(self) -> None:
+        """Counter cache should stay in sync when allow_channels.set(...) is used."""
+        game: Game = Game.objects.create(
+            twitch_id="counter_cache_set_game",
+            name="Counter Cache Set Game",
+            display_name="Counter Cache Set Game",
+        )
+        channel1: Channel = Channel.objects.create(
+            twitch_id="counter_cache_set_channel_1",
+            name="countercachesetchannel1",
+            display_name="Counter Cache Set Channel 1",
+        )
+        channel2: Channel = Channel.objects.create(
+            twitch_id="counter_cache_set_channel_2",
+            name="countercachesetchannel2",
+            display_name="Counter Cache Set Channel 2",
+        )
+        campaign: DropCampaign = DropCampaign.objects.create(
+            twitch_id="counter_cache_set_campaign",
+            name="Counter Cache Set Campaign",
+            game=game,
+            operation_names=["DropCampaignDetails"],
+        )
+
+        campaign.allow_channels.set([channel1, channel2])
+        channel1.refresh_from_db()
+        channel2.refresh_from_db()
+        assert channel1.allowed_campaign_count == 1
+        assert channel2.allowed_campaign_count == 1
+
+        campaign.allow_channels.set([channel2])
+        channel1.refresh_from_db()
+        channel2.refresh_from_db()
+        assert channel1.allowed_campaign_count == 0
+        assert channel2.allowed_campaign_count == 1
+
     @pytest.mark.django_db
     def test_dashboard_view(self, client: Client) -> None:
         """Test dashboard view returns 200 and has grouped campaign data in context."""

twitch/views.py

@@ -9,6 +9,7 @@ from collections import defaultdict
 from typing import TYPE_CHECKING
 from typing import Any
 from typing import Literal
+from urllib.parse import urlencode
 
 from django.core.paginator import EmptyPage
 from django.core.paginator import Page
@@ -1253,19 +1254,8 @@ class ChannelListView(ListView):
         Returns:
             QuerySet: Filtered channels.
         """
-        queryset: QuerySet[Channel] = super().get_queryset()
         search_query: str | None = self.request.GET.get("search")
-
-        if search_query:
-            queryset = queryset.filter(
-                Q(name__icontains=search_query)
-                | Q(display_name__icontains=search_query),
-            )
-
-        return queryset.annotate(campaign_count=Count("allowed_campaigns")).order_by(
-            "-campaign_count",
-            "name",
-        )
+        return Channel.for_list_view(search_query)
 
     def get_context_data(self, **kwargs) -> dict[str, Any]:
         """Add additional context data.
@@ -1277,12 +1267,11 @@ class ChannelListView(ListView):
             dict: Context data.
         """
         context: dict[str, Any] = super().get_context_data(**kwargs)
-        search_query: str = self.request.GET.get("search", "")
+        search_query: str = self.request.GET.get("search", "").strip()
 
         # Build pagination info
-        base_url = "/channels/"
-        if search_query:
-            base_url += f"?search={search_query}"
+        query_string: str = urlencode({"search": search_query}) if search_query else ""
+        base_url: str = f"/channels/?{query_string}" if query_string else "/channels/"
 
         page_obj: Page | None = context.get("page_obj")
         pagination_info: list[dict[str, str]] | None = (