Fixes image attachments

bookwyrm/models/activitypub_mixin.py

@@ -445,7 +445,11 @@ def unfurl_related_field(related_field, sort_field=None):
             unfurl_related_field(i) for i in related_field.order_by(sort_field).all()
         ]
     if related_field.reverse_unfurl:
-        return related_field.field_to_activity()
+        # if it's a one-to-one (key pair)
+        if hasattr(related_field, "field_to_activity"):
+            return related_field.field_to_activity()
+        # if it's one-to-many (attachments)
+        return related_field.to_activity()
     return related_field.remote_id
 
 

bookwyrm/models/attachment.py

@@ -25,7 +25,11 @@ class Image(Attachment):
     """ an image attachment """
 
     image = fields.ImageField(
-        upload_to="status/", null=True, blank=True, activitypub_field="url"
+        upload_to="status/",
+        null=True,
+        blank=True,
+        activitypub_field="url",
+        alt_field="caption",
     )
     caption = fields.TextField(null=True, blank=True, activitypub_field="name")