Expose bayesian rating average for add-ons in the API

docs/topics/api/addons.rst

@@ -138,6 +138,7 @@ This endpoint allows you to fetch a specific add-on by id, slug or guid.
     :>json object ratings: Object holding ratings summary information about the add-on.
     :>json int ratings.count: The number of user ratings for the add-on.
     :>json float ratings.average: The average user rating for the add-on.
+    :>json float ratings.bayesian_average: The bayesian average user rating for the add-on.
     :>json string review_url: The URL to the review page for the add-on.
     :>json string slug: The add-on slug.
     :>json string status: The :ref:`add-on status <addon-detail-status>`.

src/olympia/addons/serializers.py

@@ -265,6 +265,7 @@ class AddonSerializer(serializers.ModelSerializer):
     def get_ratings(self, obj):
         return {
             'average': obj.average_rating,
+            'bayesian_average': obj.bayesian_rating,
             'count': obj.total_reviews,
         }
 

src/olympia/addons/tests/test_serializers.py

@@ -71,6 +71,7 @@ class AddonSerializerOutputTestMixin(object):
         self.addon = addon_factory(
             average_daily_users=4242,
             average_rating=4.21,
+            bayesian_rating=4.22,
             category=cat1,
             description=u'My Addôn description',
             file_kw={
@@ -199,6 +200,7 @@ class AddonSerializerOutputTestMixin(object):
 
         assert result['ratings'] == {
             'average': self.addon.average_rating,
+            'bayesian_average': self.addon.bayesian_rating,
             'count': self.addon.total_reviews,
         }
         assert result['public_stats'] == self.addon.public_stats