Style collection 404 page like rest of blog

This displays the "page is missing" text within the same page as any
other blog post, keeping customizations, pinned pages, and general blog
navigation.

Ref T493

posts.go

@@ -1295,14 +1295,32 @@ func viewCollectionPost(app *App, w http.ResponseWriter, r *http.Request) error
 		coll.Owner = owner
 	}
 
+	postFound := true
 	p, err := app.db.GetPost(slug, coll.ID)
 	if err != nil {
-		if err == ErrCollectionPageNotFound && slug == "feed" {
+		if err == ErrCollectionPageNotFound {
-			// User tried to access blog feed without a trailing slash, and
+			postFound = false
-			// there's no post with a slug "feed"
+
-			return impart.HTTPError{http.StatusFound, c.CanonicalURL() + "/feed/"}
+			if slug == "feed" {
+				// User tried to access blog feed without a trailing slash, and
+				// there's no post with a slug "feed"
+				return impart.HTTPError{http.StatusFound, c.CanonicalURL() + "/feed/"}
+			}
+
+			po := &Post{
+				Slug:     null.NewString(slug, true),
+				Font:     "norm",
+				Language: zero.NewString("en", true),
+				RTL:      zero.NewBool(false, true),
+				Content: `<p class="msg">This page is missing.</p>
+
+Are you sure it was ever here?`,
+			}
+			pp := po.processPost()
+			p = &pp
+		} else {
+			return err
 		}
-		return err
 	}
 	p.IsOwner = owner != nil && p.OwnerID.Valid && owner.ID == p.OwnerID.Int64
 	p.Collection = coll
@@ -1324,11 +1342,18 @@ func viewCollectionPost(app *App, w http.ResponseWriter, r *http.Request) error
 			contentType = "text/markdown"
 		}
 		w.Header().Set("Content-Type", fmt.Sprintf("%s; charset=utf-8", contentType))
+		if !postFound {
+			w.WriteHeader(http.StatusNotFound)
+		}
+
 		if isMarkdown && p.Title.String != "" {
 			fmt.Fprintf(w, "# %s\n\n", p.Title.String)
 		}
 		fmt.Fprint(w, p.Content)
 	} else if strings.Contains(r.Header.Get("Accept"), "application/activity+json") {
+		if !postFound {
+			w.WriteHeader(http.StatusNotFound)
+		}
 		p.extractData()
 		ap := p.ActivityObject()
 		ap.Context = []interface{}{activitystreams.Namespace}
@@ -1345,14 +1370,20 @@ func viewCollectionPost(app *App, w http.ResponseWriter, r *http.Request) error
 			IsPinned       bool
 			IsCustomDomain bool
 			PinnedPosts    *[]PublicPost
+			IsFound        bool
 		}{
 			PublicPost:     p,
 			StaticPage:     pageForReq(app, r),
 			IsOwner:        cr.isCollOwner,
 			IsCustomDomain: cr.isCustomDomain,
+			IsFound:        postFound,
 		}
 		tp.PinnedPosts, _ = app.db.GetPinnedPosts(coll)
 		tp.IsPinned = len(*tp.PinnedPosts) > 0 && PostsContains(tp.PinnedPosts, p)
+
+		if !postFound {
+			w.WriteHeader(http.StatusNotFound)
+		}
 		if err := templates["collection-post"].ExecuteTemplate(w, "post", tp); err != nil {
 			log.Error("Error in collection-post template: %v", err)
 		}

templates/collection-post.tmpl

@@ -8,6 +8,7 @@
 		<link rel="stylesheet" type="text/css" href="/css/write.css" />
 		<link rel="shortcut icon" href="/favicon.ico" />
 		<meta name="viewport" content="width=device-width, initial-scale=1.0" />
+		{{ if .IsFound }}
 		<link rel="canonical" href="{{.CanonicalURL}}" />
 		<meta name="generator" content="WriteFreely">
 		<meta name="title" content="{{.PlainDisplayTitle}} {{localhtml "title dash" .Language.String}} {{if .Collection.Title}}{{.Collection.Title}}{{else}}{{.Collection.Alias}}{{end}}">
@@ -29,6 +30,7 @@
 		<meta property="og:updated_time" content="{{.Created8601}}" />
 		{{range .Images}}<meta property="og:image" content="{{.}}" />{{else}}<meta property="og:image" content="{{.Collection.AvatarURL}}">{{end}}
 		<meta property="article:published_time" content="{{.Created8601}}">
+		{{ end }}
 		{{if .Collection.StyleSheet}}<style type="text/css">{{.Collection.StyleSheetDisplay}}</style>{{end}}
 
 		{{if .Collection.RenderMathJax}}
@@ -50,14 +52,14 @@
 				{{if .PinnedPosts}}
 				{{range .PinnedPosts}}<a class="pinned{{if eq .Slug.String $.Slug.String}} selected{{end}}" href="{{if not $.SingleUser}}/{{$.Collection.Alias}}/{{.Slug.String}}{{else}}{{.CanonicalURL}}{{end}}">{{.PlainDisplayTitle}}</a>{{end}}
 				{{end}}
-				{{ if .IsOwner }}<span class="views" dir="ltr"><strong>{{largeNumFmt .Views}}</strong> {{pluralize "view" "views" .Views}}</span>
+				{{ if and .IsOwner .IsFound }}<span class="views" dir="ltr"><strong>{{largeNumFmt .Views}}</strong> {{pluralize "view" "views" .Views}}</span>
 				<a class="xtra-feature" href="/{{if not .SingleUser}}{{.Collection.Alias}}/{{end}}{{.Slug.String}}/edit" dir="{{.Direction}}">Edit</a>
 				{{if .IsPinned}}<a class="xtra-feature unpin" href="/{{.Collection.Alias}}/{{.Slug.String}}/unpin" dir="{{.Direction}}" onclick="unpinPost(event, '{{.ID}}')">Unpin</a>{{end}}
 				{{ end }}
 			</nav>
 		</header>
 		
-		<article id="post-body" class="{{.Font}} h-entry">{{if .IsScheduled}}<p class="badge">Scheduled</p>{{end}}{{if .Title.String}}<h2 id="title" class="p-name">{{.FormattedDisplayTitle}}</h2>{{end}}<div class="e-content">{{.HTMLContent}}</div></article>
+		<article id="post-body" class="{{.Font}} h-entry {{if not .IsFound}}error-page{{end}}">{{if .IsScheduled}}<p class="badge">Scheduled</p>{{end}}{{if .Title.String}}<h2 id="title" class="p-name">{{.FormattedDisplayTitle}}</h2>{{end}}<div class="e-content">{{.HTMLContent}}</div></article>
 
 		{{ if .Collection.ShowFooterBranding }}
 		<footer dir="ltr"><hr><nav><p style="font-size: 0.9em">{{localhtml "published with write.as" .Language.String}}</p></nav></footer>