Fix tagged posts falsely showing Older link

collections.go

@@ -975,7 +975,14 @@ func handleViewCollectionTag(app *App, w http.ResponseWriter, r *http.Request) e
 
 	coll := newDisplayCollection(c, cr, page)
 
-	coll.TotalPages = int(math.Ceil(float64(coll.TotalPosts) / float64(coll.Format.PostsPerPage())))
+	taggedPostIDs, err := app.db.GetAllPostsTaggedIDs(c, tag, cr.isCollOwner)
+	if err != nil {
+		return err
+	}
+
+	ttlPosts := len(taggedPostIDs)
+	pagePosts := coll.Format.PostsPerPage()
+	coll.TotalPages = int(math.Ceil(float64(ttlPosts) / float64(pagePosts)))
 	if coll.TotalPages > 0 && page > coll.TotalPages {
 		redirURL := fmt.Sprintf("/page/%d", coll.TotalPages)
 		if !app.cfg.App.SingleUser {

database.go

@@ -113,6 +113,7 @@ type writestore interface {
 
 	GetPostsCount(c *CollectionObj, includeFuture bool)
 	GetPosts(cfg *config.Config, c *Collection, page int, includeFuture, forceRecentFirst, includePinned bool) (*[]PublicPost, error)
+	GetAllPostsTaggedIDs(c *Collection, tag string, includeFuture bool) ([]string, error)
 	GetPostsTagged(cfg *config.Config, c *Collection, tag string, page int, includeFuture bool) (*[]PublicPost, error)
 
 	GetAPFollowers(c *Collection) (*[]RemoteUser, error)
@@ -1195,6 +1196,51 @@ func (db *datastore) GetPosts(cfg *config.Config, c *Collection, page int, inclu
 	return &posts, nil
 }
 
+func (db *datastore) GetAllPostsTaggedIDs(c *Collection, tag string, includeFuture bool) ([]string, error) {
+	collID := c.ID
+
+	cf := c.NewFormat()
+	order := "DESC"
+	if cf.Ascending() {
+		order = "ASC"
+	}
+
+	timeCondition := ""
+	if !includeFuture {
+		timeCondition = "AND created <= NOW()"
+	}
+	var rows *sql.Rows
+	var err error
+	if db.driverName == driverSQLite {
+		rows, err = db.Query("SELECT id FROM posts WHERE collection_id = ? AND LOWER(content) regexp ? "+timeCondition+" ORDER BY created "+order, collID, `.*#`+strings.ToLower(tag)+`\b.*`)
+	} else {
+		rows, err = db.Query("SELECT id FROM posts WHERE collection_id = ? AND LOWER(content) RLIKE ? "+timeCondition+" ORDER BY created "+order, collID, "#"+strings.ToLower(tag)+"[[:>:]]")
+	}
+	if err != nil {
+		log.Error("Failed selecting tagged posts: %v", err)
+		return nil, impart.HTTPError{http.StatusInternalServerError, "Couldn't retrieve tagged collection posts."}
+	}
+	defer rows.Close()
+
+	ids := []string{}
+	for rows.Next() {
+		var id string
+		err = rows.Scan(&id)
+		if err != nil {
+			log.Error("Failed scanning row: %v", err)
+			break
+		}
+
+		ids = append(ids, id)
+	}
+	err = rows.Err()
+	if err != nil {
+		log.Error("Error after Next() on rows: %v", err)
+	}
+
+	return ids, nil
+}
+
 // GetPostsTagged retrieves all posts on the given Collection that contain the
 // given tag.
 // It will return future posts if `includeFuture` is true.

templates/collection-tags.tmpl

@@ -63,8 +63,8 @@
 			{{template "posts" .}}
 
 		{{if gt .TotalPages 1}}<nav id="paging" class="content-container clearfix">
-			{{if or (and .Format.Ascending (le .CurrentPage .TotalPages)) (isRTL .Direction)}}
-				{{if gt .CurrentPage 1}}<a href="{{.PrevPageURL .Prefix .CurrentPage .IsTopLevel}}">&#8672; {{if and .Format.Ascending (le .CurrentPage .TotalPages)}}Previous{{else}}Newer{{end}}</a>{{end}}
+			{{if or (and .Format.Ascending (lt .CurrentPage .TotalPages)) (isRTL .Direction)}}
+				{{if gt .CurrentPage 1}}<a href="{{.PrevPageURL .Prefix .CurrentPage .IsTopLevel}}">&#8672; {{if and .Format.Ascending (lt .CurrentPage .TotalPages)}}Previous{{else}}Newer{{end}}</a>{{end}}
 				{{if lt .CurrentPage .TotalPages}}<a style="float:right;" href="{{.NextPageURL .Prefix .CurrentPage .IsTopLevel}}">{{if and .Format.Ascending (lt .CurrentPage .TotalPages)}}Next{{else}}Older{{end}} &#8674;</a>{{end}}
 			{{else}}
 				{{if lt .CurrentPage .TotalPages}}<a href="{{.NextPageURL .Prefix .CurrentPage .IsTopLevel}}">&#8672; Older</a>{{end}}