Make average rating property of Edition model

bookwyrm/models/book.py

@@ -9,7 +9,7 @@
 from django.contrib.postgres.indexes import GinIndex
 from django.core.cache import cache
 from django.db import models, transaction
-from django.db.models import Prefetch, ManyToManyField
+from django.db.models import Avg, Prefetch, ManyToManyField
 from django.dispatch import receiver
 from django.utils.translation import gettext_lazy as _
 from model_utils import FieldTracker
@@ -19,6 +19,7 @@
 
 from bookwyrm import activitypub
 from bookwyrm.isbn.isbn import hyphenator_singleton as hyphenator
+from bookwyrm.models.status import Review
 from bookwyrm.preview_images import generate_edition_preview_image_task
 from bookwyrm.settings import (
     BASE_URL,
@@ -491,6 +492,12 @@ def hyphenated_isbn13(self):
         """generate the hyphenated version of the ISBN-13"""
         return hyphenator.hyphenate(self.isbn_13)
 
+    @property
+    def average_rating(self, user):
+        """generate average rating of a book"""
+        reviews = Review.privacy_filter(user).filter(book__parent_work__editions=self)
+        return reviews.aggregate(Avg("rating"))["rating__avg"]
+
     def get_rank(self):
         """calculate how complete the data is on this edition"""
         rank = 0

bookwyrm/views/books/books.py

@@ -4,7 +4,7 @@
 
 from django.contrib.auth.decorators import login_required, permission_required
 from django.core.paginator import Paginator
-from django.db.models import Avg, Q
+from django.db.models import Q
 from django.http import Http404
 from django.shortcuts import get_object_or_404, redirect
 from django.template.response import TemplateResponse
@@ -98,7 +98,7 @@ def get(self, request, book_id, **kwargs):
                 if not user_statuses
                 else None
             ),
-            "rating": reviews.aggregate(Avg("rating"))["rating__avg"],
+            "rating": book.average_rating(request.user),
             "lists": lists,
             "update_error": kwargs.get("update_error", False),
         }