Replace image_serialzier helper with built-in serializers

bookwyrm/models/status.py

@@ -19,7 +19,6 @@ from bookwyrm.settings import ENABLE_PREVIEW_IMAGES
 from .activitypub_mixin import ActivitypubMixin, ActivityMixin
 from .activitypub_mixin import OrderedCollectionPageMixin
 from .base_model import BookWyrmModel
-from .fields import image_serializer
 from .readthrough import ProgressMode
 from . import fields
 
@@ -190,15 +189,8 @@ class Status(OrderedCollectionPageMixin, BookWyrmModel):
             if hasattr(activity, "name"):
                 activity.name = self.pure_name
             activity.type = self.pure_type
-            activity.attachment = [
-                image_serializer(b.cover, b.alt_text)
-                for b in self.mention_books.all()[:4]
-                if b.cover
-            ]
-            if hasattr(self, "book") and self.book.cover:
-                activity.attachment.append(
-                    image_serializer(self.book.cover, self.book.alt_text)
-                )
+            covers = [b.to_activity().get("cover") for b in [getattr(self, "book", None)] + list(self.mention_books.all()) if b]
+            activity.attachment = covers
         return activity
 
     def to_activity(self, pure=False):  # pylint: disable=arguments-differ