Use a cached property for the latest build

Author: davidfischer

readthedocs/core/templatetags/privacy_tags.py

@@ -28,7 +28,7 @@ def get_public_projects(context, user):
     )
     # Filters the latest builds of projects.
     latest_build = Prefetch('builds', Build.objects.filter(
-        pk__in=subquery), to_attr='_latest_build'
+        pk__in=subquery), to_attr=Project.LATEST_BUILD_CACHE
     )
     # 'Exists()' checks if the project has any good builds.
     projects = Project.objects.for_user_and_viewer(

readthedocs/projects/models.py

@@ -392,6 +392,9 @@ class Project(models.Model):
     objects = ProjectQuerySet.as_manager()
     all_objects = models.Manager()
 
+    # Property used for storing the latest build for a project when prefetching
+    LATEST_BUILD_CACHE = '_latest_build'
+
     class Meta:
         ordering = ('slug',)
         permissions = (
@@ -857,7 +860,7 @@ def get_latest_build(self, finished=True):
         """
         # Check if there is `_latest_build` attribute in the Queryset.
         # Used for Database optimization.
-        if hasattr(self, '_latest_build'):
+        if hasattr(self, self.LATEST_BUILD_CACHE):
             if self._latest_build:
                 return self._latest_build[0]
             return None

readthedocs/projects/querysets.py

@@ -90,7 +90,7 @@ def dashboard(self, user=None):
         latest_build = Prefetch(
             'builds',
             Build.objects.filter(pk__in=subquery),
-            to_attr='_latest_build',
+            to_attr=self.model.LATEST_BUILD_CACHE,
         )
 
         return projects.prefetch_related(latest_build)