Update UI message feed via polling

process_manager/templates/process_manager/index.html

@@ -56,9 +56,9 @@
         </div>
         <div class="card-body" id="message-list">
           <ul class="list-group">
-            {% if messages %}
-              {% for message in messages %}<li class="list-group-item">{{ message }}</li>{% endfor %}
-            {% endif %}
+            <div hx-get="{% url 'process_manager:messages' %}"
+                 hx-trigger="every 1s"
+                 hx-swap="afterend"></div>
           </ul>
         </div>
       </div>

process_manager/templates/process_manager/partials/message_items.html

@@ -0,0 +1 @@
+{% for message in messages %}<li class="list-group-item">{{ message }}</li>{% endfor %}

process_manager/urls.py

@@ -8,6 +8,7 @@
 
 partial_urlpatterns = [
     path("process_table/", partials.process_table, name="process_table"),
+    path("messages/", partials.messages, name="messages"),
 ]
 
 urlpatterns = [

process_manager/views/pages.py

@@ -4,7 +4,6 @@
 
 from django.contrib.auth.decorators import login_required, permission_required
 from django.contrib.auth.mixins import PermissionRequiredMixin
-from django.db import transaction
 from django.http import HttpRequest, HttpResponse
 from django.shortcuts import render
 from django.urls import reverse_lazy
@@ -17,16 +16,7 @@
 @login_required
 def index(request: HttpRequest) -> HttpResponse:
     """View that renders the index/home page."""
-    with transaction.atomic():
-        # atomic to avoid race condition with kafka consumer
-        messages = request.session.load().get("messages", [])
-        request.session.pop("messages", [])
-        request.session.save()
-
-    context = {"messages": messages}
-    return render(
-        request=request, context=context, template_name="process_manager/index.html"
-    )
+    return render(request=request, template_name="process_manager/index.html")
 
 
 @login_required

process_manager/views/partials.py

@@ -2,6 +2,7 @@
 
 import django_tables2
 from django.contrib.auth.decorators import login_required
+from django.db import transaction
 from django.http import HttpRequest, HttpResponse
 from django.shortcuts import render
 from druncschema.process_manager_pb2 import (
@@ -52,3 +53,19 @@ def process_table(request: HttpRequest) -> HttpResponse:
         context=dict(table=table),
         template_name="process_manager/partials/process_table.html",
     )
+
+
+@login_required
+def messages(request: HttpRequest) -> HttpResponse:
+    """Renders and pops Kafka messages from the user's session."""
+    with transaction.atomic():
+        # atomic to avoid race condition with kafka consumer
+        messages = request.session.load().get("messages", [])
+        request.session.pop("messages", [])
+        request.session.save()
+
+    return render(
+        request=request,
+        context=dict(messages=messages[::-1]),
+        template_name="process_manager/partials/message_items.html",
+    )

tests/process_manager/views/test_page_views.py

@@ -18,24 +18,6 @@ def test_authenticated(self, auth_client):
             response = auth_client.get(self.endpoint)
         assert response.status_code == HTTPStatus.OK
 
-    def test_session_messages(self, auth_client):
-        """Test the rendering of messages from the user session into the view."""
-        from django.contrib.sessions.backends.db import SessionStore
-        from django.contrib.sessions.models import Session
-
-        session = Session.objects.get()
-        message_data = ["message 1", "message 2"]
-        store = SessionStore(session_key=session.session_key)
-        store["messages"] = message_data
-        store.save()
-
-        response = auth_client.get(self.endpoint)
-        assert response.status_code == HTTPStatus.OK
-
-        # messages have been removed from the session and added to the context
-        assert response.context["messages"] == message_data
-        assert "messages" not in store.load()
-
 
 class TestLogsView(PermissionRequiredTest):
     """Tests for the logs view."""

tests/process_manager/views/test_partial_views.py

@@ -4,6 +4,7 @@
 
 import pytest
 from django.urls import reverse
+from pytest_django.asserts import assertTemplateUsed
 
 from process_manager.tables import ProcessTable
 
@@ -47,3 +48,28 @@ def test_post_checked_rows(self, mocker, auth_client):
 
         for row in table.data.data:
             assert row["checked"] == (row["uuid"] in selected_uuids)
+
+
+class TestMessagesView(LoginRequiredTest):
+    """Test the process_manager.views.messages view function."""
+
+    endpoint = reverse("process_manager:messages")
+
+    def test_get(self, auth_client):
+        """Tests basic calls of view method."""
+        from django.contrib.sessions.backends.db import SessionStore
+        from django.contrib.sessions.models import Session
+
+        session = Session.objects.get()
+        message_data = ["message 1", "message 2"]
+        store = SessionStore(session_key=session.session_key)
+        store["messages"] = message_data
+        store.save()
+
+        with assertTemplateUsed("process_manager/partials/message_items.html"):
+            response = auth_client.get(self.endpoint)
+        assert response.status_code == HTTPStatus.OK
+
+        # messages have been removed from the session and added to the context
+        assert response.context["messages"] == message_data[::-1]
+        assert "messages" not in store.load()