Add size of enclosure to RSS feed

website/common/models.py

@@ -36,6 +36,7 @@ from .utils import (
     extract_text,
     get_site_title,
     get_table_of_contents,
+    get_url_mime_type,
     truncate_string,
 )
 
@@ -189,6 +190,16 @@ class BaseContentPage(BasePage, MetadataMixin):
     def get_meta_image_url(self, request: HttpRequest) -> Optional[str]:
         return self.hero_url("regular", "|format-png")
 
+    def get_meta_image_mime(self) -> Optional[str]:
+        if self.hero_unsplash_photo_id is not None:
+            return get_url_mime_type(self.hero_url("regular"))
+
+        elif self.hero_image_id is not None:
+            # We force these to PNG in `get_meta_image_url`
+            return "image/png"
+
+        return None
+
     def get_meta_title(self) -> str:
         return self.html_title
 

website/common/utils.py

@@ -1,7 +1,8 @@
 from dataclasses import dataclass
 from itertools import islice, pairwise
-from typing import Iterable, Type
+from typing import Iterable, Optional, Type
 
+import requests
 from bs4 import BeautifulSoup, SoupStrainer
 from django.conf import settings
 from django.http.request import HttpRequest
@@ -107,3 +108,11 @@ def heading_id(heading: str) -> str:
 @django_cache_decorator(time=300)
 def get_site_title() -> str:
     return Site.objects.values_list("site_name", flat=True).first()
+
+
+@django_cache_decorator(time=21600)
+def get_url_mime_type(url: str) -> Optional[str]:
+    try:
+        return requests.head(url).headers.get("Content-Type")
+    except requests.exceptions.RequestException:
+        return None

website/common/views.py

@@ -115,17 +115,22 @@ class AllPagesFeed(Feed):
         return getattr(item, "summary", None) or item.title
 
     def item_enclosure_url(self, item: BasePage) -> Optional[str]:
-        if not hasattr(item, "hero_image_url"):
+        if not hasattr(item, "get_meta_image_url"):
             return ""
 
-        hero_image_url = item.hero_image_url()
+        image_url = item.get_meta_image_url(self.request)
 
-        if hero_image_url and hero_image_url.startswith("/"):
-            return self.request.build_absolute_uri(hero_image_url)
+        if image_url and image_url.startswith("/"):
+            return self.request.build_absolute_uri(image_url)
 
-        return hero_image_url
+        return image_url
+
+    def item_enclosure_mime_type(self, item: BasePage) -> str:
+        if not hasattr(item, "get_meta_image_mime"):
+            return ""
+
+        return item.get_meta_image_mime() or ""
 
-    item_enclosure_mime_type = ""
     item_enclosure_length = 0