handle discord channels in serializers

apps/api/serializers.py

@@ -10,6 +10,7 @@ from apps.home.models import (
     ContentFilter,
     MessageMutator,
     MessageStyle,
+    DiscordChannel,
     Subscription,
     Content,
     UniqueContentRule
@@ -170,11 +171,18 @@ class UniqueContentRuleSerializer(DynamicModelSerializer):
         fields = ("id", "name", "value")
 
 
+class DiscordChannelSerializer(DynamicModelSerializer):
+    class Meta:
+        model = DiscordChannel
+        fields = ("id", "channel_id")
+
+
 class SubscriptionSerializer(DynamicModelSerializer):
     filters = serializers.PrimaryKeyRelatedField(
         queryset=ContentFilter.objects.all(),
         many=True
     )
+    channels = DiscordChannelSerializer(many=True)
     #  unique_rules = UniqueContentRuleSerializer(many=True)  # TODO: solve? causes issues with submission.
 
     class Meta:
@@ -189,11 +197,28 @@ class SubscriptionSerializer(DynamicModelSerializer):
             "extra_notes",
             "active",
             "publish_threshold",
+            "channels",
             "filters",
             "message_style",
             "unique_rules"
         )
 
+    def _delete_unused_channels(self):
+        referenced_channel_ids = set(Subscription.objects.values_list("channels__channel_id", flat=True))
+        del_count, _ = DiscordChannel.objects.exclude(channel_id__in=referenced_channel_ids).delete()
+        log.info("Deleted %s unreferenced DiscordChannel object(s).", del_count)
+
+    def update(self, instance, validated_data):
+        channels = validated_data.pop("channels")
+
+        instance.channels.clear()
+        for channel_id in channels:
+            channel, created = DiscordChannel.objects.get_or_create(channel_id=channel_id)
+            instance.channels.add(channel)
+
+        self._delete_unused_channels()
+        return super().update(instance, validated_data)
+
     def validate(self, data):
         server = data.get("server") or self.context.get("server")
         if not server: