Serve 503 when PocketBase is unavailable across all content pages

Elternbeirat.Web/Features/Posts/PostDetail.razor.cs

@@ -1,33 +1,42 @@
-using System.Globalization;
 using Elternbeirat.Contracts;
 using Elternbeirat.PocketBase;
 using Elternbeirat.Web.Shared;
 using Microsoft.AspNetCore.Components;
-using Microsoft.AspNetCore.Http;
 
 namespace Elternbeirat.Web.Features.Posts;
 
 public partial class PostDetail
 {
-    private static readonly CultureInfo German = CultureInfo.GetCultureInfo("de-DE");
-
-    [LoggerMessage(Level = LogLevel.Warning, Message = "Could not load post '{slug}' from PocketBase.")]
-    private static partial void LogLoadFailed(ILogger logger, string slug, Exception exception);
+    [LoggerMessage(
+        Level = LogLevel.Error,
+        Message = "Could not load post '{Slug}' from PocketBase; content source is unavailable.")]
+    private static partial void LogSourceUnavailable(
+        ILogger logger,
+        string slug,
+        Exception exception);
 
     [Parameter]
     public string Slug { get; set; } = string.Empty;
 
     [Inject]
-    private PocketBaseClient PocketBase { get; set; } = default!;
+    private PocketBaseClient PocketBase { get; set; } = null!;
 
     [Inject]
-    private ILogger<PostDetail> Logger { get; set; } = default!;
+    private ILogger<PostDetail> Logger { get; set; } = null!;
+
+    [Inject]
+    private NavigationManager Navigation { get; set; } = null!;
 
     [CascadingParameter]
     private HttpContext? HttpContext { get; set; }
 
     private Post? _post;
 
+    // Set when the content source could not be reached or read. The markup then
+    // shows a "temporarily unavailable" note instead of a not-found page, matching
+    // the 503 this sets on the response.
+    private bool _unavailable;
+
     // The post body rendered from Markdown to HTML, ready to emit as a
     // MarkupString in the markup.
     private MarkupString Body => (MarkupString)Markdown.ToHtml(_post?.Body);
@@ -36,24 +45,23 @@ public partial class PostDetail
     {
         try
         {
-            var posts = await PocketBase.GetPostsAsync();
+            var posts = await PocketBase.GetPostsAsync(HttpContext?.RequestAborted ?? CancellationToken.None);
             _post = posts.FirstOrDefault(
-                p => string.Equals(p.Slug, Slug, StringComparison.OrdinalIgnoreCase));
+                post => string.Equals(post.Slug, Slug, StringComparison.OrdinalIgnoreCase));
         }
-        catch (HttpRequestException ex)
+        catch (PocketBaseUnavailableException exception)
         {
-            // Source unreachable -> treat as "not found" rather than a 500. The
-            // 404 branch below serves the friendly /not-found page.
-            LogLoadFailed(Logger, Slug, ex);
-            _post = null;
+            // The site works, its data store is down: 503, not 404.
+            LogSourceUnavailable(Logger, Slug, exception);
+            _unavailable = true;
+            SourceUnavailable.SetStatus(HttpContext);
+            return;
         }
 
-        // Unknown slug (or unreachable source) -> 404, so
-        // UseStatusCodePagesWithReExecute serves the /not-found page instead of an
-        // empty 200 response.
-        if (_post is null && HttpContext is not null)
+        if (_post is null)
         {
-            HttpContext.Response.StatusCode = StatusCodes.Status404NotFound;
+            // The source answered, but there is no post with this slug: a genuine 404.
+            Navigation.NotFound();
         }
     }
 }