Cache title author snippet

bookwyrm/models/author.py

@@ -1,6 +1,8 @@
 """ database schema for info about authors """
 import re
 from django.contrib.postgres.indexes import GinIndex
+from django.core.cache import cache
+from django.core.cache.utils import make_template_fragment_key
 from django.db import models
 
 from bookwyrm import activitypub
@@ -34,6 +36,17 @@ class Author(BookDataModel):
     )
     bio = fields.HtmlField(null=True, blank=True)
 
+    def save(self, *args, **kwargs):
+        """clear related template caches"""
+        # clear template caches
+        cache_keys = [
+            make_template_fragment_key("titleby", [book])
+            for book in self.book_set.values_list("id", flat=True)
+        ]
+        cache.delete_many(cache_keys)
+
+        return super().save(*args, **kwargs)
+
     @property
     def isni_link(self):
         """generate the url from the isni id"""