Serve 503 when PocketBase is unavailable across all content pages

Elternbeirat.Web/Features/Events/EventList.razor.cs

@@ -1,48 +1,67 @@
 using Elternbeirat.Contracts;
 using Elternbeirat.PocketBase;
+using Elternbeirat.Web.Shared;
 using Microsoft.AspNetCore.Components;
 
 namespace Elternbeirat.Web.Features.Events;
 
 public partial class EventList
 {
-    [LoggerMessage(Level = LogLevel.Warning, Message = "Could not load events from PocketBase.")]
-    private static partial void LogLoadFailed(ILogger logger, Exception exception);
+    [LoggerMessage(
+        Level = LogLevel.Error,
+        Message = "Could not load events from PocketBase; content source is unavailable.")]
+    private static partial void LogSourceUnavailable(
+        ILogger logger,
+        Exception exception);
 
     [Inject]
-    private PocketBaseClient PocketBase { get; set; } = default!;
+    private PocketBaseClient PocketBase { get; set; } = null!;
 
     [Inject]
-    private ILogger<EventList> Logger { get; set; } = default!;
+    private ILogger<EventList> Logger { get; set; } = null!;
+
+    [CascadingParameter]
+    private HttpContext? HttpContext { get; set; }
 
     private IReadOnlyList<Event> _upcoming = [];
     private IReadOnlyList<Event> _past = [];
 
+    // Set when the content source could not be reached or read. The markup then
+    // shows a "temporarily unavailable" note instead of "no events", matching the
+    // 503 this sets on the response.
+    private bool _unavailable;
+
     protected override async Task OnInitializedAsync()
     {
         IReadOnlyList<Event> events;
         try
         {
-            events = await PocketBase.GetEventsAsync();
+            events = await PocketBase.GetEventsAsync(HttpContext?.RequestAborted ?? CancellationToken.None);
         }
-        catch (HttpRequestException ex)
+        catch (PocketBaseUnavailableException exception)
         {
-            // Source unreachable -> show empty sections instead of a 500. The page
-            // stays up; the "keine Termine" note is rendered.
-            LogLoadFailed(Logger, ex);
+            // Empty sections would claim there are no events. The site works, its
+            // data store is down: 503 and an honest note.
+            LogSourceUnavailable(Logger, exception);
+            _unavailable = true;
+            SourceUnavailable.SetStatus(HttpContext);
             return;
         }
 
         // Split into upcoming and past by date, so an event earlier today still
         // counts as upcoming. Upcoming earliest first, past most recent first.
         var today = DateOnly.FromDateTime(DateTime.Today);
-        _upcoming = events
-            .Where(e => DateOnly.FromDateTime(e.Start) >= today)
-            .OrderBy(e => e.Start)
-            .ToList();
-        _past = events
-            .Where(e => DateOnly.FromDateTime(e.Start) < today)
-            .OrderByDescending(e => e.Start)
-            .ToList();
+        _upcoming =
+        [
+            .. events
+                .Where(@event => DateOnly.FromDateTime(@event.Start) >= today)
+                .OrderBy(@event => @event.Start)
+        ];
+        _past =
+        [
+            .. events
+                .Where(@event => DateOnly.FromDateTime(@event.Start) < today)
+                .OrderByDescending(@event => @event.Start)
+        ];
     }
 }