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