prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  On Century Detail pages, sometimes unpublished sources are listed
  Visiting century/3863 while not logged in, there's a link to source/672452. When I click on it, I get a 403 Access Denied error. We need to ensure that links to sources that are inaccessible to a user are never displayed.
  
  This bug occurs on both staging and production.
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `django/cantusdb_project/main_app/views/century.py`
  Content:
  ```
  1 from django.views.generic import DetailView
  2 from main_app.models import Century
  3 
  4 class CenturyDetailView(DetailView):
  5     model = Century
  6     context_object_name = "century"
  7     template_name = "century_detail.html"
  8
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/django/cantusdb_project/main_app/views/century.py b/django/cantusdb_project/main_app/views/century.py
  --- a/django/cantusdb_project/main_app/views/century.py
  +++ b/django/cantusdb_project/main_app/views/century.py
  @@ -1,7 +1,20 @@
   from django.views.generic import DetailView
  -from main_app.models import Century
  +from main_app.models import Century, Source
  +from typing import Any
   
   class CenturyDetailView(DetailView):
       model = Century
       context_object_name = "century"
       template_name = "century_detail.html"
  +
  +    def get_context_data(self, **kwargs: Any) -> dict[str, Any]:
  +        context = super().get_context_data(**kwargs)
  +        century = self.get_object()
  +        user = self.request.user
  +        display_unpublished = user.is_authenticated
  +        sources = Source.objects.filter(century=century)
  +        if not display_unpublished:
  +            sources = sources.filter(published=True)
  +        sources=sources.only("title", "id")
  +        context["sources"] = sources
  +        return context
  \ No newline at end of file
  
verification_info: {"golden_diff": "diff --git a/django/cantusdb_project/main_app/views/century.py b/django/cantusdb_project/main_app/views/century.py\n--- a/django/cantusdb_project/main_app/views/century.py\n+++ b/django/cantusdb_project/main_app/views/century.py\n@@ -1,7 +1,20 @@\n from django.views.generic import DetailView\n-from main_app.models import Century\n+from main_app.models import Century, Source\n+from typing import Any\n \n class CenturyDetailView(DetailView):\n     model = Century\n     context_object_name = \"century\"\n     template_name = \"century_detail.html\"\n+\n+    def get_context_data(self, **kwargs: Any) -> dict[str, Any]:\n+        context = super().get_context_data(**kwargs)\n+        century = self.get_object()\n+        user = self.request.user\n+        display_unpublished = user.is_authenticated\n+        sources = Source.objects.filter(century=century)\n+        if not display_unpublished:\n+            sources = sources.filter(published=True)\n+        sources=sources.only(\"title\", \"id\")\n+        context[\"sources\"] = sources\n+        return context\n\\ No newline at end of file\n", "issue": "On Century Detail pages, sometimes unpublished sources are listed\nVisiting century/3863 while not logged in, there's a link to source/672452. When I click on it, I get a 403 Access Denied error. We need to ensure that links to sources that are inaccessible to a user are never displayed.\r\n\r\nThis bug occurs on both staging and production.\n", "before_files": [{"content": "from django.views.generic import DetailView\nfrom main_app.models import Century\n\nclass CenturyDetailView(DetailView):\n    model = Century\n    context_object_name = \"century\"\n    template_name = \"century_detail.html\"\n", "path": "django/cantusdb_project/main_app/views/century.py"}], "after_files": [{"content": "from django.views.generic import DetailView\nfrom main_app.models import Century, Source\nfrom typing import Any\n\nclass CenturyDetailView(DetailView):\n    model = Century\n    context_object_name = \"century\"\n    template_name = \"century_detail.html\"\n\n    def get_context_data(self, **kwargs: Any) -> dict[str, Any]:\n        context = super().get_context_data(**kwargs)\n        century = self.get_object()\n        user = self.request.user\n        display_unpublished = user.is_authenticated\n        sources = Source.objects.filter(century=century)\n        if not display_unpublished:\n            sources = sources.filter(published=True)\n        sources=sources.only(\"title\", \"id\")\n        context[\"sources\"] = sources\n        return context", "path": "django/cantusdb_project/main_app/views/century.py"}]}