feat: add comprehensive GitHub workflow and development tools

app/.venv/Lib/site-packages/django/contrib/messages/views.py

@@ -0,0 +1,19 @@
+from django.contrib import messages
+
+
+class SuccessMessageMixin:
+    """
+    Add a success message on successful form submission.
+    """
+
+    success_message = ""
+
+    def form_valid(self, form):
+        response = super().form_valid(form)
+        success_message = self.get_success_message(form.cleaned_data)
+        if success_message:
+            messages.success(self.request, success_message)
+        return response
+
+    def get_success_message(self, cleaned_data):
+        return self.success_message % cleaned_data