Base /api/v1/followed_tags off of HashtagFollow models

This is due to the Tag model not having a dedicated ID which is needed
for pagination.

api/schemas.py

@@ -287,6 +287,24 @@ class Tag(Schema):
         return cls(**hashtag.to_mastodon_json(followed=followed))
 
 
+class FollowedTag(Tag):
+    id: str
+
+    @classmethod
+    def from_follow(
+        cls,
+        follow: users_models.HashtagFollow,
+    ) -> "FollowedTag":
+        return cls(id=follow.id, **follow.hashtag.to_mastodon_json(followed=True))
+
+    @classmethod
+    def map_from_follows(
+        cls,
+        hashtag_follows: list[users_models.HashtagFollow],
+    ) -> list["Tag"]:
+        return [cls.from_follow(follow) for follow in hashtag_follows]
+
+
 class FeaturedTag(Schema):
     id: str
     name: str

api/views/tags.py

@@ -6,6 +6,7 @@ from activities.models import Hashtag
 from api import schemas
 from api.decorators import scope_required
 from api.pagination import MastodonPaginator, PaginatingApiResponse, PaginationResult
+from users.models import HashtagFollow
 
 
 @scope_required("read:follows")
@@ -17,10 +18,9 @@ def followed_tags(
     min_id: str | None = None,
     limit: int = 100,
 ) -> list[schemas.Tag]:
-    queryset = Hashtag.objects.followed_by(request.identity)
+    queryset = HashtagFollow.objects.by_identity(request.identity)
     paginator = MastodonPaginator()
-    # TODO: this fails due to the Hashtag model not having an `id` field
-    pager: PaginationResult[Hashtag] = paginator.paginate(
+    pager: PaginationResult[HashtagFollow] = paginator.paginate(
         queryset,
         min_id=min_id,
         max_id=max_id,
@@ -28,8 +28,7 @@ def followed_tags(
         limit=limit,
     )
     return PaginatingApiResponse(
-        # TODO: add something like map_from_post to schemas.Tag
-        schemas.Tag.map_from_post(pager.results, request.identity),
+        schemas.FollowedTag.map_from_follows(pager.results),
         request=request,
         include_params=["limit"],
     )

users/models/hashtag_follow.py

@@ -5,8 +5,10 @@ from django.db import models
 
 class HashtagFollowQuerySet(models.QuerySet):
     def by_hashtags(self, hashtags: list[str]):
-        query = self.filter(hashtag_id__in=hashtags)
-        return query
+        return self.filter(hashtag_id__in=hashtags)
+
+    def by_identity(self, identity):
+        return self.filter(identity=identity)
 
 
 class HashtagFollowManager(models.Manager):
@@ -16,6 +18,9 @@ class HashtagFollowManager(models.Manager):
     def by_hashtags(self, hashtags: list[str]):
         return self.get_queryset().by_hashtags(hashtags)
 
+    def by_identity(self, identity):
+        return self.get_queryset().by_identity(identity)
+
 
 class HashtagFollow(models.Model):
     identity = models.ForeignKey(