move latest commit logic to Repository model property

Author: Shofikul-Isl4m

backend/apps/github/common.py

@@ -74,10 +74,9 @@ def sync_repository(
         year_ago = timezone.now() - td(days=365)
 
         # GitHub repository commits.
-        latest_commit = (
-            Commit.objects.filter(repository=repository).order_by("-created_at").first()
+        since = (
+            latest_commit.created_at if (latest_commit := repository.latest_commit) else year_ago
         )
-        since = latest_commit.created_at if latest_commit else year_ago
 
         commits_to_save = []
         for gh_commit in gh_repository.get_commits(since=since):

backend/apps/github/models/repository.py

@@ -113,6 +113,16 @@ def __str__(self):
         """
         return self.path
 
+    @property
+    def latest_commit(self):
+        """Get the latest commit for the repository.
+
+        Returns
+            Commit: The most recently created commit.
+
+        """
+        return self.commits.order_by("-created_at").first()
+
     @property
     def latest_pull_request(self):
         """Get the latest pull request for the repository.

backend/tests/apps/github/common_test.py

@@ -35,6 +35,7 @@ def mock_common_deps(mocker):
     mock_repository.latest_updated_milestone = None
     mock_repository.latest_updated_issue = None
     mock_repository.latest_updated_pull_request = None
+    mock_repository.latest_commit = None
     mock_repository.id = 1
 
     return mocks